Fault Isolation Procedure
- Checking the valve's power supply:
- Unplug the connector: Charge air control valve (179).
- Turn the ignition switch to the ON position.
- Connect Test Lamp (86 1 857) to pin 1 of the female connector and a good grounding point.
- Jiggle the leads and in-line connectors at several places and in different directions to reveal intermittent breaks and short circuits in the wiring harness. Observe the multimeter, test lamp or diagnostic tool while doing this.
If the test lamp illuminates, go to step 3, otherwise go to next step.
- Rectifying the lead: The lead from +15 via fuse 26 to pin 1 of the female connector is faulty. Rectify the fault and go to step 6.
- Checking the valve's control module output:
- Connect Test Lamp (86 1 857) to pins 1 and 2 of the female connector.
- Activate: Charge air control valve (max. 60 seconds) (ECM) to 100%.
- Jiggle the leads and in-line connectors at several places and in different directions to reveal intermittent breaks and short circuits in the wiring harness. Observe the multimeter, test lamp or diagnostic tool while doing this.
If the test lamp illuminates, go to step 5, otherwise go to next step.
- Rectifying the lead: The lead from pin 13 of the control module to pin 2 of the female connector is faulty. Rectify the fault and go to step 6.
- Changing components: Change the Charge air control valve. When finished, go to next step.
- Final check:
- Clear the DTCs in all systems.
- Carry out a drive cycle: Drive the car at varying engine loads and engine RPM for 5 minutes.
- Evaluate the drive cycle: Check that the DTC has not recurred.
If the trouble code has recurred, the ECM is probably at fault and will need replacement. Replace with known-good ECM and retest. If no DTCs are present, then the steps taken to rectify the fault were correct.
Courtesy of SAAB-SCANIA OF AMERICA, INC.