What are the steps to diagnose and check the vehicle speed control system? a) Connect a vacuum pump to the vacuum hose of the check valve correspon...

To diagnose and check the vehicle speed control system, you can follow the following steps: a) Connect a vacuum pump to the vacuum hose of the check valve corresponding to the tank. Apply vacuum. The vacuum of the tank should not be lost. If the vacuum is lost, replace the one-way check valve. b) Connect a vacuum pump to the vacuum hose of the check valve corresponding to the vacuum source of the check valve. Apply vacuum. The vacuum should flow through the valve. If the vacuum does not flow, replace the one-way check valve. Seal the connection at the opposite end of the valve with a finger and apply vacuum. If the vacuum is not maintained, it means that the diaphragm contained in the check valve has been broken. Replace the valve. c) To proceed with a complete diagnosis of the speed control system, including the speed control servo, consult the appropriate transmission mechanism diagnostic procedures manual. d) If the operator repeatedly presses and releases the set button, with the foot off the accelerator ("set with foot raised" to start the speed control operation), the vehicle may accelerate and exceed the desired fixed speed by 8 km/h (5 mph) and then decelerate to less than the desired fixed speed before finally reaching it. e) The speed control has an adaptive strategy to compensate, from one vehicle to another, for the variations that exist in the length of the speed control cables. When the speed control is set with the operator's foot off the accelerator pedal, the speed control interprets that there is excessive loosening of the speed control cable and adapts. If set with foot raised is used continuously, the overextension/subextension condition of the speed control occurs. Remember to consult the appropriate transmission mechanism diagnostic procedures manual for a complete diagnosis of the speed control system.