Tempostat allows you to automatically maintain the selected vehicle speed. The tempostat servomotor is located in the engine compartment, mounted on the mudguard of the left wing and connected to the throttle rod by a cable. The main components of the system are a servo motor, brake light switch, control switches, speed sensors and executive relays. Checking the individual functions of the system requires the use of special diagnostic equipment and its implementation lies outside the qualifications of the average amateur mechanic. Below is a description of only the procedures for the most common checks, which make it possible to identify the causes of the most typical tempostat failures.
1. Find the tempostat fuse and check its condition (see Fuses - general information).
2. The actuation of the brake light sensor-switch that reacts to the foot brake pedal should lead to the deactivation of the tempostat. Have an assistant depress the brake pedal and check that the brake lights are working properly.
3. If the brake lights do not respond to pressing the pedal, find out the cause of the failure and repeat the check of the tempostat functioning.
4. Check the condition of the drive cable routed from the servomotor/tempostat amplifier assembly (see accompanying illustration) to the throttle linkage. Replace damaged or worn cable.
5. The operation of the tempostat is based on monitoring the vehicle speed. The speed sensor is placed in the transmission, a description of its verification is given in Chapter Engine management systems this guide.
6. Carry out a road test of the vehicle. If it was not possible to eliminate the malfunction of the tempostat during the corrections made, drive the car to a service station for a more detailed diagnosis of the system using special equipment.