Checking the forced-run and mixture enrichment system with the throttle valve fully open on the RV engine (VW Passat B4)

Warm up the engine (oil temperature not less than 80°C) and let it idle. Manually close the contact of the full load switch of the throttle valve. Using a screwdriver, move the throttle valve so that the engine speed reaches about 2000 rpm and remains at this level. In this case, the engine mode should fluctuate, which indicates that the forced idle system has been activated.

If the idle speed control system does not turn on, disconnect the connector (blue color) coolant temperature sensor of the engine control subsystem and short-circuit the terminals of the sensor block. If the engine speed fluctuates, the switch must be replaced. If this does not happen, check the wires and their connection in the coolant temperature sensor circuit and / or the power supply circuit of the idle and full load switches and repair the damage. If this does not give a result, replace the controller.