Passat L4-1984cc 2.0L DOHC (9A) (1990)
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Engine Control Module: Testing and Inspection
Voltage Measurements
Grounds
*
Voltage depends on engine temperature.
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Check ECU plug for terminal in position 20 may not have a pin 20.
Battery supply
Main Relay Supply
Reference Supply
Coolant Temperature Sensor
ISC Valve
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The DC voltage will decrease when the engine is running . Voltage is inversely proportional to the duty cycle that controls the ISC valve.
