We connect the tester probes to the "B" terminal and the engine "ground".
With the ignition on, measure the voltage of the sensor input signal circuit.
The device should record a voltage of 4.5–5.5 V.
If the voltage does not match, check the serviceability of the circuit (open circuit and short circuit to ground) between terminal "B" of the wiring harness connector and terminal "M28" of the ECU wiring harness connector.
Having connected the tester probes to the terminal "A" of the block and the engine "ground", we measure the resistance of the "ground" circuit.
If the sensor ground circuit is in good condition, the device should record a resistance of less than 1 Ohm.
The reason for increased resistance may be an unreliable connection in the pads connected to the sensor or to the ECU.
If the sensor circuits are OK, the ECU is faulty.
To check the coolant temperature sensor…
…we connect the tester probes to the sensor terminals.
We measure the resistance of the sensor for two values of coolant temperature - unheated and warmed up engine.
We compare the obtained values with the control ones (see table).
For a more accurate check of the sensor, it must be removed (see Removal the coolant temperature sensor).
We lower the sensor into a vessel with water and heat the vessel.
We measure the resistance of the sensor at different temperatures.
We control the temperature with a thermometer.
We compare the obtained values with the control ones (see table).
Control values of coolant temperature sensor resistance at different coolant temperatures (approximately)
| Coolant temperature,°C | Resistance, Ohm |
| 100 | 180 |
| 90 | 240 |
| 80 | 330 |
| 70 | 470 |
| 60 | 670 |
| 50 | 970 |
| 45 | 1 200 |
| 40 | 1 460 |
| 35 | 1 800 |
| 30 | 2 240 |
| 25 | 2 800 |
| 20 | 3 520 |
| 15 | 4 450 |
| 10 | 5 670 |
| 0 | 9 420 |
| -4 | 12 300 |
| -10 | 16 180 |
| -15 | 21 450 |
| -20 | 28 680 |
If the measured resistance values do not match the control values, the sensor must be replaced.
[The material was created based on information from the website «CHEVYMAN.RU»]