Signal Too Low

Signal too low

Checking the function of the water pump

Note! On cars where the heater functions as a parking heater there is no +15 voltage supply to the control module. Individual components and functions cannot be activated when the +15 voltage supply is absent.




- Ignition on
- Activate the water pump.
Listen for a buzzing sound which indicates that the water pump is running.





Does the water pump function?

Yes - Intermittent fault

No - Checking the connectors

-------------------------------------------------

Checking the connectors

Note! On cars where the heater functions as a parking heater there is no +15 voltage supply to the control module. Individual components and functions cannot be activated when the +15 voltage supply is absent.








- Ignition off
- Check the water pump and control module connector. Check for contact resistance and oxidation according to Checking wiring and terminals. Permanent fault Checking Wiring And Terminals. Permanent Fault.
Check for damage carefully
- Reinstall the components, reconnect the connectors etc.
- Ignition on
- Activate the water pump.
Listen for a buzzing sound which indicates that the water pump is running.
If the water pump now functions, the cause of the fault was loose connections in the connectors.

Other information:
- To access the control module or connect the breakout box, see
- To access or replace the water pump, see Replacing the water pump Replacing Water Pump.





Does the water pump function?

Yes - FAULT FOUND

No - Checking components and wiring

-------------------------------------------------

Checking components and wiring
Check the cable between control module terminal #12 and water pump terminal 1. Check for an open-circuit according to Checking wiring and terminals. Permanent fault Checking Wiring And Terminals. Permanent Fault. Check for a short-circuit to ground according to Checking wiring and terminals. Permanent fault Checking Wiring And Terminals. Permanent Fault.
Check the cable between control module terminal #11 and water pump terminal 2. Check for an open-circuit according to Checking wiring and terminals. Permanent fault Checking Wiring And Terminals. Permanent Fault.
The water pump must be changed if no fault is found on the cable.

Note! If there is a fault in the power supply cable, diagnostic trouble code (DTC) HEA-815 Combustion fan, signal and/or HEA-825 Fuel pump (FP), signal may be stored.

Remedy as necessary.

Other information:
- To access the control module or connect the breakout box, see
- To access or replace the water pump, see Replacing the water pump Replacing Water Pump
- For other values, see Signal specification Additional heater 912-D/B Signal Specification Additional Heater 912-D/B.













Select Continue.

Continue - Verification

-------------------------------------------------

Verification




Verification

Verification

Hint: After carrying out the repair, check that the fault has been remedied.

Note! On cars where the heater functions as a parking heater there is no +15 voltage supply to the control module. Individual components and functions cannot be activated when the +15 voltage supply is absent.








- Ignition off
- Reinstall the connectors, components etc.
- Ignition on
- Activate the water pump.
Listen for a buzzing sound which indicates that the water pump is running.





Does the water pump function?

Yes - VERIFIED

No - VERIFICATION FAILEDPAPER

------------------------

VERIFICATION FAILED - Fault-tracing information

VERIFIED - FAULT FOUND

-------------------------------------------------

Fault-tracing information




Information

Fault-tracing information
The fault should have been detected and remedied. As this is not the case fault-tracing has failed.
Exit fault-tracing for this diagnostic trouble code (DTC) or make another attempt.

Do you want to exit fault-tracing?

Yes - FAULT-TRACING FAILED

No - Attempt New Test

------------------------

FAULT-TRACING FAILED - FAULT-TRACING FAILED

Attempt New Test - Checking the function of the water pump

-------------------------------------------------

Intermittent fault
Check the water pump and control module connectors. Check for contact resistance and oxidation according to Checking wiring and terminals. Permanent fault Checking Wiring And Terminals. Permanent Fault.
Check the cable between control module terminal #12 and water pump terminal 1. Check for an intermittent open-circuit according to Checking wiring and terminals. Intermittent faults Checking Wiring And Terminals. Intermittent Faults. Check for a short-circuit to ground according to Checking wiring and terminals. Intermittent faults Checking Wiring And Terminals. Intermittent Faults.
Check the cable between control module terminal #11 and water pump terminal 2. Check for an intermittent open-circuit according to Checking wiring and terminals. Intermittent faults Checking Wiring And Terminals. Intermittent Faults.
Remedy as necessary.

Other information:
- To access the control module or connect the breakout box, see
- To access or replace the water pump, see Replacing the water pump Replacing Water Pump
- For other values, see Signal specification Additional heater 912-D/B Signal Specification Additional Heater 912-D/B.













Select Continue.

Continue - Fault-tracing information
DONE

-------------------------------------------------

Fault-tracing information




Information

Fault-tracing information
If the fault is intermittent, do not verify fault-tracing if the fault does not recur.
It is possible to view the information again, or leave fault-tracing for this diagnostic trouble code (DTC).

Do you want to view the information again?

Yes - Attempt New Test

No - FAULT FOUND

------------------------

Attempt New Test - Checking the function of the water pump

DONE - DONE

FAULT FOUND - FAULT FOUND

-------------------------------------------------