1. System «Cruise control» ensures that the vehicle maintains a given speed. The system elements are an electronic control unit (RSM), servomotor, brake pedal position sensor (VRR), switches and wiring connecting the listed elements. The design of this system does not provide for the presence of mechanical or vacuum connecting elements. When diagnosing some system elements, it is necessary to use special equipment and perform special procedures, the description of which is beyond the scope of this manual. Therefore, only some general diagnostic procedures are described below, during which it is possible to determine the source of the malfunction.
2. Inspect the fuses (see subsection 3).
3. The system is turned off through the brake pedal position sensor (VRR) (or brake light switch). When checking the functionality of the brake lights, have the help of an assistant who will turn them on and off during the test (When voltage is applied to the brake light switch, the system turns off «Cruise control»).
4. If the brake lights do not turn on or continue to work after releasing the brake pedal, correct the problem and check the system functionality again «Cruise control».
5. Inspect the wiring between the PCM and the servomotor for an open or short circuit. If necessary, restore the circuit.
6. System operating parameters come from the PCM, as well as from the vehicle speed sensor located in the transmission or transfer case housing. Vehicle speed sensor (VSS) described in detail in Chapter 6.
7. Perform a road test on the vehicle to ensure system functionality «Cruise control». If the system is inoperative, contact a service and repair station to identify and repair the problem.