K-Jetronic. Function test
Switch on the ignition and check if the control valve buzzes and vibrates. If so, then carry out a control check.
Otherwise, disconnect the control valve plug, connect an ohmmeter to both plug contacts and check the continuity. The prescribed resistance value is a meager value.
Check temperature sensor. If no fault is found, in accordance with the electrical diagram, check the wiring and connections, if necessary, replace the control unit (workshop work).
Control check
Prerequisite for checking: idle adjustment must be in order.
Warm up the engine to an engine oil temperature of at least +80°C.
With the ignition off, in accordance with the instruction manual, connect an ammeter between the control valve and the plug block (serial connection).
Turn off all electrical consumers, including the air conditioning system.
Start the engine and let it idle.
Measure and record the control current supplied to the control valve.
Compress the hose of the idle speed stabilization system with pliers. The control current must increase.
Open the hose, the control current must decrease.
The control current must drop below about 430 mA. If the current does not fall below 430 mA, check the parts in the following sequence.
Check throttle angle sensor.
In accordance with the wiring diagram, check the wiring and connections, if necessary, replace the control unit.
Disconnect plug above ignition coil. Measure the control current again. The prescribed value is 415445 mA. If the measured value is outside the specified range, replace the control unit.
Remove measuring instruments.
If parts of the stabilization system were replaced, check the idle speed and CO content adjustment, if necessary, adjust the indicated values.
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