SAAB WIS ONLINE

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, throttle position sensor and the tank pressure sensor are all grounded from control module pin 67. The leads to the crankshaft position sensor and the power leads from the oxygen sensors are screened to pin 67 as well.

Diagnosis


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




Reference ground

Reference ground is taken on control module pin 66 from the sensor ground leads so that the coolant temperature can be read with greater accuracy. Driveability problems will occur while the engine is warming up if there is no 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.

Reference ground is taken from the two oxygen sensors to 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.

• A break to pin 47 will generate diagnostic trouble code P0131 and/or P0140.