Instrument Cluster / Carrier

B1725

Turbo pressure gauge

Fault symptoms
Turbo pressure gauge in bottom position.

Condition
Short circuit to B+ in signal lead from Trionic.

Diagnostic help
A reading of the current turbo pressure can be obtained with the diagnostic tool.
The turbo pressure gauge can also be activated with the diagnostic tool.

Check the wiring harness
Jiggle the wiring harness at several points and in different directions to detect intermittent breaks and short-circuits in the leads. Observe the multimeter, test lamp or diagnostic tool during the test.

Diagnostic procedure

1. Check the fault symptoms






Is the "CHECK ENGINE" lamp on in the main instrument unit?
YES
- See fault diagnosis in Computers and Control Systems.
NO
- Go to step 2.

2. Check the sensor ground connection
- Unplug connector: Main instrument unit (22-pin connector): (540).






- Connect a test lamp to B+ and pin 6 of the female connector.






- The test lamp should light up.






Is the function correct?
YES
- Go to step 3.
NO
- Repair or replace the lead between pin 6 of the MIU's 22-pin connector and pin 66 or 67 of the Trionic.
- Go to step 6.

3. Check the control module's sensor input
- Turn the ignition switch to ON.






- Take a voltage reading.
- Red test lead: Main instrument unit (22-pin connector): 14.






- Black test lead: Vehicle battery: B-.






- Value should be: 1.8 V.

Is the function correct?
YES
- Go to step 6.
NO
- Go to step 4.

4. Checking the wiring harness
- Check the lead between pin 14 of the MIU's 22- pin connector and pin 20 of the Trionic.






Is the lead OK?
YES
- Go to step 5.
NO
- Repair or replace the lead between pin 14 of the MIU's 22- pin connector and pin 20 of the Trionic.
- Go to step 6.

5. Final check
- Clear the diagnostic trouble codes in all systems.






- Carry out a drive cycle:
- Drive the car at varying engine loads and rpm for five minutes.






- Evaluate the drive cycle:
- Check that no diagnostic trouble codes recur.






Is the function correct?
YES
- The steps taken to rectify the fault were correct.
NO
- See "Before changing a control module."

6. Final check






- Perform a functional test.






- Check that no diagnostic trouble codes recur.






Is the function correct?
YES
- The steps taken to rectify the fault were correct.
NO
- See Fault diagnosis, general, "Before changing a control module." Before Changing A Control Module