Instrument Cluster / Carrier

B1715

Coolant temperature gauge

Fault symptoms
Coolant temperature gauge in bottom position.

Condition
Break/short circuit in coolant temperature gauge circuit.

Diagnostic help
A reading of the current coolant temperature can be obtained with the diagnostic tool.
The coolant temperature 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. Checking sensor ground
- Unplug the connector: Temperature sensor, coolant, instrument: (45).






- Connect a test lamp to B+ and pin 1 of the female connector.






- The test lamp should light up.






Is the function correct?
YES
- Go to step 2.
NO
- Repair or replace the lead between pin 7 of the MIU's 22-pin connector and pin 1 of the sensor.
- Go to step 4.

2. Check the control module's sensor input
- Contact Main instrument unit.






- Read value: Coolant temperature.
- A reading of -40 °C should be obtained.

Is the function correct?
YES
- Go to step 3.
NO
- Repair or replace the lead between pin 15 of the MIU's 22-pin connector and pin 2 of the sensor.
- Go to step 4.

3. Check the control module's sensor input (continued)
- Connect a jumper between pins 1 and 2 of the female connector.






- Read value: Coolant temperature.
- A reading of 150 °C should be obtained.

Is the function correct?
YES
- Change: Temperature sensor, coolant, instrument.
- Go to step 4.
NO
- Repair or replace the lead between pin 15 of the MIU's 22-pin connector and pin 2 of the sensor.
- Go to step 4.

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






- 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