Fuel system diagnostics (Chevrolet Captiva 1)

Fuel system diagnostics

Description of the scheme

The fuel pump is located in the fuel tank and is mounted on the fuel sender assembly. The fuel pump remains on as long as the engine is cranked or running or the ECM receives reference pulses from the crankshaft position sensor. If there are no reference pulses, the ECM will turn off the fuel pump two seconds after the ignition is turned on or two seconds after the engine is stopped. The fuel pump delivers fuel to the fuel rail and to the fuel injectors, the fuel pump assembly maintains fuel system pressure in the range of 401 to 418 kPa (from 58 to 61 psi). Excess fuel is returned to the fuel tank.

Caution! The fuel system is under pressure. Before disconnecting the fuel lines, relieve the pressure in the fuel supply system to avoid fuel spillage and burns.

Caution: Do not pinch or kink nylon fuel lines to avoid fuel leakage and possible fires or injuries.

Relieving pressure in the fuel supply system

1. Remove the fuel cap.

2. Remove the fuel pump fuse EF16 from the engine fuse box.

3. Start the engine and turn it off.

4. Crank the engine for another 10 seconds.

Fuel system diagnostics

Step	Operation	Values	Yes	No
1	Relieve pressure in the fuel supply system. Install the fuel pressure gauge. Turn on the ignition. Fuel pressure within the set value, but not stable?	401~418 kPa (58~61 psi)	Jump to operations 2	Jump to operations 9
2	Check fuel lines for leaks. Malfunction detected?	-	Jump to operations 3	Jump to operations 4
3	Replace the fuel line if necessary. Install the fuel pressure gauge. Turn on the ignition. Fuel pressure within the set value, but not stable?	401~418 kPa (58~61 psi)	The system is normal	-
4	Remove the fuel pump assembly. Check the fuel pump connecting hoses for pressure leaks. Malfunction detected?	-	Jump to operations 5	Jump to operations 6
5	Tighten or replace fuel pump connecting hoses if necessary. Install the fuel pressure gauge. Turn on the ignition. Fuel pressure within the set value, but not stable?	401~418 kPa (58~61 psi)	The system is normal	-
6	Replace the fuel pump assembly. Install the fuel pressure gauge. Turn on the ignition. Fuel pressure within the set value, but not stable?	401~418 kPa (58~61 psi)	The system is normal	-
7	Remove the fuel rail and fuel injectors as an assembly. Check all fuel injectors for leaks under fuel system pressure. Malfunction detected?	-	Jump to operations 8	-
8	Replace leaking fuel injectors. Install the fuel pressure gauge. Turn on the ignition. Fuel pressure within the set value, but not stable?	401~418 kPa (58~61 psi)	The system is normal	-
9	Relieve pressure in the fuel supply system. Install the fuel pressure gauge. Turn on the ignition. Is the fuel pressure below the set value and remains stable?	401~418 kPa (58~61 psi)	Jump to operations 6	Jump to operations 10
10	Check fuel lines for leaks. Malfunction detected?	-	Jump to operations 3	Jump to operations 11
11	Remove the fuel pump assembly. Check the fuel pump connecting hoses for pressure leaks. Malfunction detected?	-	Jump to operations 5	Jump to operations 12
12	Remove the fuel rail and fuel injectors as an assembly. Check all fuel injectors for leaks under fuel system pressure. Malfunction detected?	-	Jump to operations 8	Jump to operations 6

Checking the fuel pump relay circuit; Checking the fuel pump relay circuit; Checking the electric fuel pump relay circuit

Description of the scheme

When the ignition is turned on, the ECM sends a signal to the battery to activate the fuel pump relay and operate the fuel pump in the fuel tank. The fuel pump operates as long as the engine is cranked or running and the ECM receives ignition control pulses.

If there are no control pulses, the ECM will turn off the fuel pump within 2 seconds after the ignition is turned on.

Diagnostic information

An intermittent problem could be caused by a poor connection, worn insulation, or a broken wire under the insulation.

Description of the test

The sequence corresponds to the steps indicated in the diagnostic table.

3. This operation checks the ground signal supplied by the ECM to control the fuel pump relay.

7. By checking the wiring using steps 2 - 6, you can detect a faulty fuel pump relay.

9. Once it is determined that there is no ground signal from the ECM to the fuel pump relay, it can be assumed that the fault is in the ECM or in the wiring between the ECM and the fuel pump relay.

Checking the fuel pump relay circuit; Checking the fuel pump relay circuit; Checking the electric fuel pump relay circuit

Step	Operation	Values	Yes	No
1	Turn off the ignition for 10 seconds. Turn on the ignition. Listen to the operation of the fuel pump in the fuel tank. Does the fuel pump operate for the specified time?	2 sec.	The system is normal	Jump to operations 2
2	Turn off the ignition. Disconnect the fuel pump relay. Connect a test lamp between terminal 30 of the fuel pump relay connector and ground. Turn on the ignition. Does the indicator light come on?	-	Jump to operations 3	Jump to operations 8
3	Turn off the ignition. Connect a test lamp between terminal 85 of the fuel pump relay connector and the positive battery cable. Turn on the ignition. When the ignition is on, the indicator lamp should light for the set time. Is the indicator light on?	2 sec.	Jump to operations 4	Jump to operations 9
4	Turn off the ignition. Connect a test lamp between terminal 30 of the fuel pump relay connector and ground. Is the indicator light on?	-	Jump to operations 5	Jump to operations 11
5	Check the wire between terminal 87 of the fuel pump relay connector and terminal 4 of the fuel pump connector for an open circuit or a short to ground. Malfunction detected?	-	Jump to operations 6	Jump to operations 7
6	Repair the wire between terminal 87 of the fuel pump relay connector and terminal 3 of the fuel pump connector. Install the fuel pump relay. Turn off the ignition for 10 seconds. Turn on the ignition. Does the fuel pump operate for the specified time?	2 sec.	The system is normal	-
7	Replace the fuel pump relay. Turn off the ignition for 10 seconds. Turn on the ignition. Does the fuel pump operate for the specified time?	2 sec.	The system is normal	-
8	Check for open circuit between terminal 30 of the fuel pump relay connector and the battery. Malfunction detected?	-	Jump to operations 13	-
9	Check the wire between terminal 85 of the fuel pump relay connector and terminal 51 of the J1 connector of the ECM for an open circuit. Problem found?	-	Jump to operations 10	Jump to operations 12
10	Repair the wire between terminal 85 of the fuel pump relay connector and terminal 51 of the J1 connector of the ECM. Install the fuel pump relay. Turn off the ignition for 10 seconds. Turn on the ignition. Does the fuel pump operate for the specified time?	2 sec.	The system is normal	-
11	Replace fuse Ef16 or repair the wire between terminal 30 of the fuel pump relay connector and the battery. Install the fuel pump relay. Turn off the ignition for 10 seconds. Turn on the ignition. Does the fuel pump operate for the specified time?	2 sec.	The system is normal	-
12	Turn off the ignition. Replace the ECM. Turn on the ignition. Does the fuel pump operate for the specified time?	2 sec.	The system is normal	-
13	Replace fuse Ef16 or repair the wire between terminal 30 of the fuel pump relay connector and the ignition system Install the fuel pump relay. Turn off the ignition for 10 seconds. Turn on the ignition. Does the fuel pump operate for the specified time?	2 sec.	The system is normal	-

Checking the main relay circuit

Description of the scheme

When the ignition is turned on or the key is moved to the START position, voltage is supplied to the main relay. The main relay then supplies voltage to fuses Ef12 and Ef15 in the fuse box in the engine compartment.

Diagnostic information

• An intermittent problem could be caused by a poor connection, worn insulation, or a broken wire under the insulation.
• A faulty main relay will prevent the vehicle from starting. There will be no voltage at the fuel injectors. Without voltage, the fuel injectors will not function.

Checking the main relay circuit

Step	Operation	Values	Yes	No
1	Turn off the ignition. Disconnect fuses Ef12 and Ef15 in the engine compartment fuse box. Turn on the ignition. Using a test lamp connected to ground, check the fuse terminals closest to the main relay for fuses Ef12 and Ef15. Does the test light come on at both terminals?	-	The system is normal	Jump to operations 2
2	Check the indicator light. Does the indicator light only light on one terminal?	-	Jump to operations 9	Jump to operations 3
3	Check the indicator light. The test lamp does not light on both terminals?	-	Jump to operations 4	-
4	Turn off the ignition. Check fuse Ef13 in the engine compartment fuse box. Is the fuse ok?	-	Jump to operations 5	Jump to operations 10
5	Disconnect the main relay. Connect a test lamp between terminal 85 of the main relay connector and ground. Is the indicator light on?	-	Jump to operations 6	Jump to operations 11
6	Connect a test lamp between terminal 86 of the main relay connector and battery voltage. Is the indicator light on?	-	Jump to operations 7	Jump to operations 12
7	Connect a test lamp between terminal 30 of the main relay connector and ground. Is the indicator light on?	-	Jump to operations 8	Jump to operations 13
8	Check for open circuit in the wire between terminal 87 of the main relay connector and the terminals of the fuse box in the engine compartment for fuses Ef12 and Ef15. Malfunction detected?	-	Jump to operations 9	Jump to operations 14
9	Repair open circuit between terminal 87 of main relay connector and engine compartment fuse box terminals for fuses Ef12 and Ef15. Is the renovation finished?	-	The system is normal	-
10	Replace fuse Ef13 in the engine compartment fuse box. Is the renovation finished?	-	The system is normal	-
11	Repair the open circuit between terminal 85 of the main relay connector and the ignition switch. Is the renovation finished?	-	The system is normal	-
12	Repair the open circuit between terminal 86 of the main relay connector and ground. Is the renovation finished?	-	The system is normal	-
13	Repair the open circuit between terminal 30 of the main relay connector and the battery. Is the renovation finished?	-	The system is normal	-
14	Replace the main relay. Is the renovation finished?	-	The system is normal	-

Checking the absolute pressure in the manifold

Description of the scheme

The manifold absolute pressure (MAP) sensor measures the change in manifold pressure associated with changes in engine load and speed. The MAP sensor converts these changes into output signals. The engine control module (ECM) supplies a 5-volt reference signal to the MAP sensor. As the intake manifold pressure changes, the MAP sensor output signal also changes. Low output signal (high vacuum) 1 - 2 V occurs at idle. High output signal level (low vacuum) 4.0 - 4.8 V occurs at wide open throttle. The MAP sensor is used to measure barometric pressure under certain conditions. This allows the ECM to make altitude adjustments. The ECM uses the MAP sensor to deliver fuel and change spark timing.

Description of the test

The sequence corresponds to the steps indicated in the diagnostic table.

2. Impact 34 kPa (10 inches Hg) the vacuum applied to the MAP sensor should cause a change in the signal level. Subtract the second signal level value from the first. The voltage value should be greater than 1.5 V. When the vacuum is applied to the MAP sensor, the signal level should change continuously. A slow change in the signal level indicates a faulty MAP sensor.

3. Disconnect the MAP sensor from the bracket and rotate the MAP sensor. Changes in the output signal greater than 0.1 V indicate a faulty connector or contact.

Checking the absolute pressure in the manifold

Step	Operation	Values	Yes	No
1	Turn off the ignition. Connect the scan tool to the data link connector (DLC). Turn on the ignition. Compare the Manifold Absolute Pressure (MAP) sensor signal level from the scanner with a known value from a working vehicle. Is the difference between the two signal levels less than the set value?	0.4 V	Jump to operations 2	Jump to operations 5
2	Turn off the ignition. Connect the scanning tool to the diagnostic connector. Disconnect the MAP sensor vacuum line. Connect a hand vacuum pump to the MAP sensor. Turn on the ignition. Record the signal level of the MAP sensor. Apply 34 kPa (10 in. Hg) vacuum to the MAP sensor and record the change in signal level. Is the difference in signal levels greater than the set value?	1.5 V	The system is normal	Jump to operations 3
3	Check the terminals of the MAP sensor connector. Malfunction detected?	-	Jump to operations 4	Jump to operations 5
4	Repair the MAP sensor connector if necessary. Is the renovation finished?	-	The system is normal	-
5	Replace the MAP sensor. Is the renovation finished?	-	The system is normal	-

Checking the ignition system

Description of the scheme

The electronic ignition system uses a twin spark ignition method with a reference spark. In this electronic ignition system, the crankshaft position sensor is mounted on the oil pump near the splined wheel, which is part of the crankshaft pulley. The crankshaft position sensor sends control pulses to the ECM. The ECM turns on the electronic ignition system coil. When the ECM turns on the electronic ignition system coil, both connected spark plugs fire simultaneously. One cylinder is in the compression stroke, while the other cylinder is in the exhaust stroke, which saves the energy needed to produce a spark in the spark plug in the cylinder in the exhaust stroke.

The remaining high voltage is used to generate a spark in the spark plug in the cylinder, which is in the compression stroke. Since the crankshaft position sensor is in a stationary position, adjustment of the ignition timing is not possible and is not necessary.

Description of the test

The sequence corresponds to the steps indicated in the diagnostic table.

2. It is important to check for spark on all cylinders to isolate the problem to the input or output signals of the electronic ignition system coil.

5. When checking the output signals for the ignition timing signal, it is recommended to use an oscilloscope to observe the signal changes. When measuring these output signals with a voltmeter, intermittent faults may occur that are not registered by the voltmeter.

6. If the ignition timing input signals from the ECM to the electronic ignition system coil are normal, then the cause of the malfunction is in the electronic ignition system coil.



11. If the CKP sensor input signals to the ECM are normal and there are no wiring issues, then the cause of the fault is in the ECM.

24. This operation, together with operation 25, checks the battery voltage and the ground contact of the electronic ignition system coil.

Checking the ignition system

Caution: To avoid electric shock when working with spark plug wires on a running engine, use insulated pliers.

Step	Operation	Values	Yes	No
1	Remove the spark plugs. Check spark plugs for moisture, cracks, improper gap, burnt electrodes or heavy deposits. Replace spark plugs if necessary. Is the renovation finished?	-	The system is normal	Jump to operations 2
2	Check for spark on all ignition wires when turning the engine with the starter. Is there spark on all ignition wires?	-	The system is normal	Jump to operations 3
3	Measure the resistance of the ignition wires. Replace all ignition wires with resistance greater than specified. Check for spark on all ignition wires. Is there spark on all ignition wires?	30,000 Ohm	The system is normal	Jump to operations 4
4	Is there spark on at least one spark plug wire, but not on all spark plug wires?	-	Jump to operations 5	Jump to operations 12
5	Turn off the ignition. Disconnect the electronic ignition system coil connector. While turning the crankshaft, measure the voltage at terminal 3 of the electronic ignition system coil connector. Does the voltage fluctuate within the set value?	0.2-2.0 V	Jump to operations 6	Jump to operations 7
6	While turning the crankshaft, measure the signal level at terminal 1 of the electronic ignition system coil connector. Does the voltage fluctuate within the set value?	0.2-2.0 V	Jump to operations 10	Jump to operations 8
7	Check for an open circuit in the wire from terminal 3 of the electronic ignition system coil connector to terminal 35 of the J2 connector of the ECM controller. Malfunction detected?	-	Jump to operations 9	Jump to operations 11
8	Check for an open circuit in the wire between terminal 1 of the electronic ignition system coil connector and terminal 40 of the J2 connector of the ECM controller. Malfunction detected?	-	Jump to operations 9	Jump to operations 11
9	Correct the faulty circuit. Connect the electronic ignition system coil connector. Check for spark on all ignition wires. Is there spark on all ignition wires?	-	The system is normal	-
10	Turn off the ignition. Replace the electronic ignition system coil. Connect the electronic ignition system coil connector. Check for spark on all ignition wires. Is there spark on all ignition wires?	-	The system is normal	-
11	Turn off the ignition. Replace the ECM. Connect the electronic ignition system coil connector. Check for spark on all ignition wires. Is there spark on all ignition wires?	-	The system is normal	-
12	Turn off the ignition. Disconnect the crankshaft position sensor (CSP) connector. Measure the resistance between terminals 1 and 2 of the crankshaft position sensor connector. Is the resistance within the set value?	400-600 Ohm	Jump to operations 13	Jump to operations 28
13	Measure the resistance between terminals 1 and 3 of the crankshaft position sensor connector. Measure the resistance between terminals 2 and 3 of the crankshaft position sensor connector. Resistance is endless (chain break)? Is the renovation finished?	-	Jump to operations 14	Jump to operations 28
14	Turn on the ignition. Measure the signal level between terminals 1 and 3 of the crankshaft position sensor connector. Is the voltage within the set value?	1.3-1.5V (2.4-2.7V)*	Jump to operations 20	Jump to operations 15
15	Measure the signal level between terminal 1 of the crankshaft position sensor connector and ground. Is the voltage within the set value?	1.3-1.5V (2.4-2.7V)*	Jump to operations 17	Jump to operations 16
16	Check for an open circuit or short circuit in the wire between terminal 1 of the crankshaft position sensor connector and terminal 14 of the J2 connector of the ECM controller. Malfunction detected?	-	Jump to operations 18	Jump to operations 11
17	Check for an open circuit in the wire between terminal 3 of the crankshaft position sensor connector and ground. Malfunction detected?	-	Jump to operations 19	Jump to operations 11
18	Repair the wire between terminal 1 of the crankshaft position sensor connector and terminal 14 of the ECM connector J2. Is the renovation finished?	-	The system is normal	-
19	Repair the wire between terminal 3 of the crankshaft position sensor connector and ground. Is the renovation finished?	-	The system is normal	-
20	Turn on the ignition. Measure the signal level between terminals 2 and 3 of the crankshaft position sensor connector. Is the voltage within the set value?	1.3-1.5V (2.4-2.7V)*	Jump to operations 24	Jump to operations 21
21	Measure the signal level between terminal 2 of the crankshaft position sensor connector and ground. Is the voltage within the set value?	1.3-1.5V (2.4-2.7V)*	Jump to operations 17	Jump to operations 22
22	Check for an open circuit or short circuit in the wire between terminal 2 of the crankshaft position sensor connector and terminal 15 of the J2 connector of the ECM controller. Malfunction detected?	-	Jump to operations 23	Jump to operations 11
23	Repair the wire between terminal 2 of the crankshaft position sensor connector and terminal 15 of the ECM connector J2. Is the renovation finished?	-	The system is normal	-
24	Turn off the ignition. Connect a test lamp between terminal 2 of the electronic ignition system coil connector and ground. Turn on the ignition. Is the indicator light on?	-	Jump to operations 25	Jump to operations 26
25	Connect a test lamp between terminal 2 of the electronic ignition system coil connector and the positive battery cable. Is the indicator light on?	-	Jump to operations 5	Go to operation 27
26	Check for an open circuit or short circuit in the wire between terminal 2 of the electronic ignition system coil connector and the ignition switch. Malfunction detected?	-	Go to operations 29	-
27	Repair the wire between terminal 3 of the electronic ignition system coil connector and ground. Is the renovation finished?	-	The system is normal	-
28	Turn off the ignition. Replace the crankshaft position sensor. Is the renovation finished?	-	The system is normal	-
29	Replace fuse F27 or repair open circuit between terminal 2 of the electronic ignition system coil connector and the ignition switch. Is the renovation finished?	-	The system is normal	-

Checking the cooling system fan circuit

Description of the scheme

The engine cooling fan circuit controls the main and auxiliary cooling system fans. The cooling system fans are controlled by the ECM controller, based on the input signals of the engine coolant temperature sensor (EST) and the air conditioning pressure sensor (ACP). The ECM controller is responsible for the operation of the cooling system fan at low RPM due to the internal grounding of terminal 43 of the ECM controller connector J1. As a result, the relay of the cooling system fan operating at low speed and the main cooling system fan operating at low speed are switched on. The ECM controller is responsible for the operation of the cooling system fan operating at high speeds, due to the internal grounding of terminal 24 of the ECM controller connector J1. As a result, the relay of the cooling system fan running at high speed turns on, and the fan starts running at high speed, since the cooling system fans are now connected in parallel.

Diagnostic information

• If the car owner complains about an overheating problem, it is necessary to determine whether the malfunction is related to actual engine overheating or overheating is only displayed on the coolant temperature indicator. If the engine overheats and the cooling fans are on, the cooling system should be checked.
• If fuse Ef9 or Ef8 in the engine compartment fuse box blows immediately after installation, check the corresponding circuit for a short to ground. If the fuses blow when the cooling fans should be turned on by the ECM, the cooling fan motor may be faulty.
• The ECM turns the cooling fans on at low speed when the coolant temperature reaches 97°C (207°F). The ECM turns the cooling fans off when the coolant temperature reaches 94°C (201°F).
• The ECM turns the cooling fans on at high speed when the coolant temperature reaches 101°C (214°F). The ECM changes the cooling fans from high speed to low speed when the coolant temperature reaches 98°C (208°F).
• The ECM turns on the low speed fans when the A/C system is on. The ECM switches the cooling fans from low speed to high speed when the A/C pressure on the high side is 1859 kPa (269 psi), then switches them back to low speed with high side A/C pressure of 1449 kPa (210 lbs/in).
• The cooling fan circuit can be quickly tested by disconnecting the ECM and grounding terminal 43 of J1. This will enable the cooling fan to run at low speed with the ignition on. Grounding terminal 24 of J1 on the ECM and turning the ignition on will enable the cooling fan to run at high speed.

Checking the cooling system fan circuit

Step	Operation	Values	Yes	No
1	Conduct a diagnostic system check. Has the check been carried out?	-	Jump to operations 2	Go to item "Checking the diagnostic system".
2	Check fuses Ef8 and Ef9 in the fuse box in the engine compartment. Replace the fuse if necessary. Is the fuse good?	-	Jump to operations 3	Jump to "Diagnostic information"
3	Turn the ignition switch to the LOCK position. If equipped, turn the air conditioner switch to the off position. Connect the scan tool to the data link connector (DLC). Start the engine. The main cooling fan should operate at low speed when the coolant temperature reaches 97°C (207°F). Is the cooling fan running at low speed?	-	Jump to operations 4	Jump to operations 8
4	The cooling fans should run at high speed when the coolant temperature reaches 101°C (214°F). Are the cooling system fans running at high speed?	-	Jump to operations 5	Jump to operations 19
5	Turn the ignition switch to the LOCK position. Start the engine. Turn on the air conditioner. Is the cooling fan running at low speed?	-	Jump to operations 7	Jump to operations 6
6	Check the air conditioning compressor clutch circuit. Repair the A/C compressor clutch circuit if necessary. Is the renovation finished?	-	The system is normal	-
7	Turn the ignition switch to the LOCK position. Connect the air conditioner pressure gauge. Start the engine. Turn the air conditioner switch to the on position and increase the speed. The cooling fan should operate at high speed when the pressure on the high pressure side of the air conditioner reaches 1859 kPa (269 psi). Are the cooling system fans running at high speed?	-	The system is normal	-
8	Turn the ignition switch to the LOCK position. Disconnect the main cooling fan connector. Turn the ignition key to the ON position. Connect a test lamp between terminal 2 of the main cooling fan connector and ground. Is the indicator light on?	-	Jump to operations 9	Jump to operations 12
9	Connect a test lamp between terminal 1 of the main cooling fan connector and the positive battery terminal. Is the indicator light on?	-	Jump to operations 11	Jump to operations 10
10	Repair the open circuit between terminal 1 of the main cooling fan connector and ground. Is the renovation finished?	-	The system is normal	-
11	Check for damage to the terminals in the main cooling fan connector and repair them or replace the main cooling fan. Is the renovation finished?	-	The system is normal	-
12	Turn the ignition key to the ON position. Connect a test light between terminals 30 and 85 of the low speed cooling fan relay connector and ground. Does the indicator light come on in both cases?	-	Jump to operations 14	Jump to operations 13
13	Restore the power supply circuit. Fuse Ef28 and terminal 85 of the low speed cooling fan relay connector. Fuse Ef8 and terminal 30 of the low speed cooling fan relay connector. Is the renovation finished?	-	The system is normal	Jump to operations 14
14	Turn the ignition switch to the LOCK position. Disconnect the engine control module (ECM) connectors. Turn the ignition key to the ON position. Connect a jumper between terminal 43 of the J1 connector of the ECM controller and ground. Is the cooling fan running at low speed?	-	Jump to operations 15	Jump to operations 16
15	Replace the ECM. Is the replacement complete?	-	The system is normal	-
16	Turn the ignition switch to the LOCK position. Measure the resistance between the following terminals: Terminal 86 of the low speed cooling fan relay and terminal 43 of the ECM connector J1. Terminal 87 of the low speed cooling fan relay and terminal 2 of the auxiliary cooling fan. Is the resistance within the set value?	0 Ohm	Jump to operations 18	Jump to operations 17
17	Fix the broken chain. Is the renovation finished?	-	The system is normal	-
18	Replace the low speed cooling fan relay. Is the replacement complete?	-	The system is normal	-
19	Turn the ignition switch to the LOCK position. Disconnect the auxiliary cooling fan connector. Turn the ignition key to the ON position. Connect a test lamp between terminal 2 of the auxiliary cooling fan connector and ground. Is the indicator light on?	-	Jump to operations 20	Jump to operations 24
20	Connect a test lamp between terminal 1 of the auxiliary cooling fan connector and the positive terminal of the battery. Is the indicator light on?	-	Jump to operations 21	Jump to operations 23
21	Replace the auxiliary cooling fan. Is the replacement complete?	-	The system is normal	Jump to operations 22
22	Repair the open circuit between the following terminals: Terminal 2 of the main cooling fan connector and terminal 87 of the high speed cooling fan relay connector. Main cooling fan connector terminal and ground. Is the renovation finished?	-	The system is normal	Jump to operations 11
23	Repair open circuit between terminal 1 of auxiliary cooling fan connector and ground. Is the renovation finished?	-	The system is normal	-
24	Turn the ignition key to the ON position. Connect a test light between the high speed cooling fan relay connector terminal and ground. Does the indicator light come on in both cases?	-	Jump to operations 26	Jump to operations 25
25	Repair the break in the power supply circuit: Fuse Ef9 and terminal 86 of the high-speed cooling fan relay connector. Fuse Ef9 and terminal 30 of the high-speed cooling fan relay connector. Is the renovation finished?	-	The system is normal	Jump to operations 26
26	Turn the ignition switch to the LOCK position. Disconnect the engine control module (ECM) connectors. Turn the ignition key to the ON position. Connect a jumper between terminal 24 of connector J1 and ground. Are the cooling system fans running at high speed?	-	Jump to operations 15	Jump to operations 27
27	Turn the ignition switch to the LOCK position. Measure the resistance between the following terminals: Terminal 86 of the high speed cooling fan relay connector and terminal 24 of the ECM connector J1. Terminal 87 of the high speed cooling fan relay connector and terminal 2 of the main cooling fan connector. Is the resistance within the set value?	0 Ohm	Go to operations 29	Jump to operations 28
28	Repair the open circuit between specific wires in the circuit. Is the renovation finished?	-	The system is normal	-
29	Replace the high speed cooling fan relay. Is the replacement complete?	-	The system is normal	Jump to operations 15

Diagnostics via diagnostic socket

Description of the scheme

The means of exchanging data with the electronic engine control system (ECM) controller is the data link connector (DLC). It is located under the instrument panel. The DLC connector is used to connect the scan tool. Power from the battery and a ground point are supplied to the scan tool through the DLC connector. The ECM controller can communicate with the scan tool due to the serial data circuit connection with the DLC connector.

Diagnostic information

Make sure the correct application has been selected on the scan tool (model line, year of manufacture, etc.). If communication cannot be established, connect the tool to another vehicle to ensure that the scan tool or cables are not causing the problem.

An intermittent fault may be caused by a poor connection, worn insulation, or a broken wire under the insulation.

Any circuit suspected of causing an intermittent fault should be carefully checked for the following conditions:

• Removed terminals.
• Poor contact of terminals.
• Defective locks.
• Deformed or damaged terminals.
• Poor connection of terminals to wires.
• Physical damage to wiring harnesses.
• Corrosion.

Description of the test

The numbers below indicate the operation numbers in the diagnostic table.

1. The diagnostic system check prompts the technician to perform basic checks and save the status and fault data to the scan tool. This creates an electronic copy of the data recorded when the fault occurred. The information is stored in the scan tool for further processing.

5. Locate and repair any short circuits that may have caused the fuse to blow if the lack of voltage in the circuit was due to a blown fuse.

10. The scan tool or its cables may be faulty. Refer to the scan tool service manual.

Diagnostics via diagnostic socket

Step	Operation	Values	Yes	No
1	Conduct a diagnostic system check. Has the check been carried out?	-	Jump to operations 2	Go to item "Checking the diagnostic system".
2	Using a test lamp connected to ground, check terminal 16 of the diagnostic connector power supply. Is the indicator light on?	-	Jump to operations 4	Jump to operations 3
3	Repair open circuit or short circuit to ground in the diagnostic connector power supply circuit. Is the renovation finished?	-	Jump to operations 4	-
4	Using a test lamp connected to the power supply, check terminals 4 and 5 of the diagnostic connector ground. Is the indicator light on?	-	Jump to operations 6	Jump to operations 5
5	Eliminate the open circuit. Is the renovation finished?	-	Jump to operations 6	-
6	Turn the ignition switch to the LOCK position. Connect the scanning tool to the diagnostic connector. Turn the ignition key to the ON position. Does the scanning device turn on?	-	Jump to operations 8	Jump to operations 7
7	Check the diagnostic connector terminal and scan tool for faults and repair if necessary. Is the renovation finished?	-	Jump to operations 8	-
8	Using a scan tool, request engine data from the ECM. Does the scan tool display any data?	-	Jump to operations 12	Jump to operations 9
9	Install the scanning device on another vehicle and check its functionality. Does the scan tool work properly on another vehicle?	-	Jump to operations 11	Jump to operations 10
10	The scanning device is faulty. Please refer to the scan tool service manual. Is the renovation finished?	-	Jump to operations 12	-
11	Repair the fault in the communication circuit between the ECM and the diagnostic connector. Is the renovation finished?	-	Jump to operations 12	-
12	Using a scan tool, clear the diagnostic trouble codes. Try to start the engine. Does the engine start and continue to run?	-	Jump to operations 13	Jump to operations 2
13	Allow the engine to idle until normal operating temperature is reached. Check to see if any diagnostic trouble codes are set? Are there any diagnostic trouble codes displayed that have not been diagnosed?	-	Go to the section "Applicable Diagnostic Trouble Codes Table"	The system is normal

Checking the balance of injectors

The fuel injector tester is turned on for a specified amount of time to deliver a measured amount of fuel into the intake manifold. This causes a pressure drop in the fuel rail that can be recorded and used to compare each fuel injector. All fuel injectors should show the same pressure drop.

Example of checking the balance of injectors

Cylinder	1	2	3	4
First meaning	296 kPa (43 psi)	296 kPa (43 psi)	296 kPa (43 psi)	296 kPa (43 psi)
Second meaning	131 kPa (19 psi)	117 kPa (17 psi)	124 kPa (18 psi)	145 kPa (21 psi)
Fall	165 kPa (24 psi)	179 kPa (26 psi)	172 kPa (25 psi)	151 kPa (22 psi)
Average range: 156~176 kPa (22.5~25.5 psi)	The injector is normal	Faulty injector - too much pressure drop	The injector is normal	Faulty injector - too little pressure drop

Caution! The fuel system is under pressure. Before disconnecting the fuel lines, relieve the pressure in the fuel supply system to avoid fuel spillage and burns.

Caution! Do not pinch or bend nylon fuel lines. Faulty fuel lines may cause fuel leakage, resulting in fire and injury.

Note: To prevent engine flooding, do not perform the injector balance check more than once (including re-testing of faulty fuel injectors) with the engine stopped.

Examination

1. Turn on the ignition to raise the fuel pressure to the maximum level.

2. Allow the fuel pressure to stabilize and record this initial pressure value. Wait until the pressure gauge needle stops moving.

3. Follow the manufacturer's directions for using the adapter harness. Turn on the fuel injector tester once and record the fuel pressure drop at the lowest point. Record this second reading. Subtract it from the first reading to determine the fuel pressure drop.

4. Disconnect the fuel pump tester from the fuel injector.

5. After turning on the ignition, to obtain the maximum fuel pressure again, connect the tester to the next fuel injector. Turn on the fuel injector tester and record the fuel pressure value. Repeat this procedure on all injectors.

6. Recheck the fuel injectors whose pressure drop exceeds 10 kPa (1.5 psi) average pressure drop.

7. Replace fuel injectors that fail the test.

8. If the pressure drop of all fuel injectors is within 10 kPa (1.5 psi) of the average pressure drop, the injectors are operating normally and do not require replacement.

9. Reconnect the fuel injector harnesses and go through the symptom diagnostic chart.

10. The engine must cool down for 10 minutes to avoid distortion of values due to fuel evaporation on a hot engine.

11. Attach the pressure gauge carefully to prevent fuel spillage.

12. The fuel pump should run for approximately 2 seconds after the ignition is turned on.

13. Place the transparent tube, installed on the pressure gauge vent valve, into a suitable container.

14. Completely bleed air from the pressure gauge and hoses.

15. The ignition must be off for at least 10 seconds to complete the ECM shutdown cycle.