P0325

DIAGNOSTIC TROUBLE CODE P0325
Knock sensor, malfunctioning or not working at all

Fault Symptom.
The car only runs at basic charging pressure, timing continuously retarded.


NOTE: The Saab Trionic system does not have a conventional knock sensor. The signal comes from the ignition discharge module.


Conditions.
No knocking signal for 10 seconds.

DIAGNOSTIC PROCEDURE

1. Checking The Knocking Signal
Connect the Scan Tool.
Start the engine.
Select "READ FUNCTIONS".
Select "KNOCK SENSOR".

The Scan Tool should show a reading of between 0 and 2.55 V, depending on the level of the knocking signal. At idling speed, it should show a reading of 0.06-0.16 V. Abrupt depression of the accelerator can cause the Scan Tool reading to vary between 0.06 and 2.55 V.

The reading shows whether or not a signal is present. If there is an open circuit in the signal lead, a reading of 0.06-0.08 V will normally be obtained, regardless of the accelerator position.

If a knocking signal is present, continue with point 4.

If no knocking signal is present, continue with point 2.







2. Checking The Electrical Interface
Unplug the ignition discharge module's 10-pin connector. Ignition switch in the ON position.

Connect a universal meter across:
- Battery positive and connector pin 7
- Battery negative and connector pin 7


The universal meter should be connected alternately to battery positive and battery negative.

When connected to battery positive, the meter shows a positive voltage reading, about 6-12 V, which rapidly drops to 0 V. When connected to battery negative, the meter shows a negative voltage reading, about -6 to -12 V, which rapidly rises to 0 V.

If the reading is OK, continue with point 4.

If the reading is not OK, continue with point 3.






3. Checking the knocking signal wiring Check the lead between pin 7 of the ignition discharge module and pin 44 of the control module for continuity.

Check The Wiring for continuity and shorting.

If the readings are OK, continue with point 3.

If any reading is not OK, rectify the fault.

4. Final Check
Clear the diagnostic trouble code, drive the car on test and check whether the trouble code is generated afresh.

If the DTC is generated again, fit an ignition discharge module that is known to be OK and then drive the car on test to check whether the DTC persists.

If it is generated again, refit the original ignition discharge module and refer to Before Replacing A Control Module.

If the DTC is not generated again, discard the original ignition discharge module.

If the DTC is not generated again, the action taken to rectify the fault was correct, otherwise the fault is of intermittent nature.