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Ground

Ground



Ground

Control module pins 24 and 25 are grounded to grounding point G7P. The ignition discharge module is also grounded to grounding point G7P.

Diagnosis


• The engine will not start if there is no ground.


Sensor ground

The crankshaft position sensor, manifold absolute pressure sensor, intake air temperature sensor, engine coolant temperature sensor and throttle position sensor are grounded from pin 67. The leads to the crankshaft position sensor and the supply leads from the oxygen sensor are screened from control module pin 67 as well.

Diagnosis


• The engine will not start if there is no sensor ground.




Reference ground

The control module receives a reference ground from the sensor ground lead on pin 66 so that it can measure the coolant temperature with greater precision. Driveability problems while the engine is warming up will occur without the reference ground to pin 66.

The main instrument unit uses the sensor ground lead (pin 67) as a reference ground in order to read the intake manifold pressure with greater accuracy. The pressure gauge will not work without reference ground from Trionic.

The control module receives reference ground from the oxygen sensor on pin 47.

Diagnosis


• A break to pin 66 will cause driveability problems when starting from cold as the temperature read by the control module will be too high.

• A break between MIU and pin 67 will make the turbo gauge go to its minimum position.

• Diagnostic trouble code P1171 will be generated if there is a break to pin 47.