Grounds

PRINCIPLE OF OPERATION, GROUND






Ground
The control module is grounded via pins 24 and 25 at grounding point G7P. The ignition discharge module is also grounded at grounding point G7R The engine will not start unless it is connected to ground.


Sensor ground
The crankshaft position sensor, manifold absolute pressure sensor intake air temperature sensor, engine coolant temperature sensor and throttle position sensor are all grounded via control module pin 67. The leads running from pin 67 of the control module to the crankshaft position sensor and the power lead from the oxygen sensor are also screened The engine will not start unless the sensors are grounded.

Reference ground
Reference ground from the sensor ground lead is connected to pin 66 of the control module. This enables the control module to measure engine coolant temperature with extra precision. Driveablity will suffer while the engine is warming up if reference ground is not connected to pin 66.

Reference ground from grounding point G7S on the engine is connected to pin 47 of the control module. This enables the control module to measure the voltage from the oxygen sensor with extra precision. The CHECK ENGINE lamp (MIL) in the main instrument display will light up if reference ground is not connected to pin 47.


Cars with ETS
On cars with ETS, the engine coolant temperature sensor contains two NTC resistors which are both grounded via the body of the sensor.

Reference ground from grounding point G7S is connected to pin 66 of the control module. This enables the control module to measure engine coolant temperature with extra precision.