HVAC

9040-LOST COMMUNICATION WITH DF

For a complete wiring diagram Consult Diagrams/Electrical.

- When Monitored:
Continuously.

- Set Condition:
The Auxiliary Electrical Heater Module (AEHM) detects DF Signal Cable fault.





Diagnostic Test

1. DTC IS ACTIVE
Turn the ignition on.
With the scan tool, read AEHM DTC's.
Is this DTC active?

Yes

- Go To 2

No

- The condition that caused this symptom is currently not present. Check for an intermittent condition by inspecting the related wiring harness for chafed, pierced, pinched, and partially broken wires. Also, inspect the related connectors for broken, bent, pushed out, spread, corroded, or contaminated terminals. Repair as necessary.
- Perform BODY VERIFICATION TEST - VER 1. Verification Tests.

2. DF SIGNAL CABLE OPEN
Disconnect the A/C Heater Control harness connector.
Disconnect the Auxiliary Electrical Heater Module (AEHM) harness connector.
Measure the resistance of the DF Signal Cable between the A/C Heater Control harness connector and the Auxiliary Electric Heater Module (AEHM) harness connector.
Does the ohm meter read open circuit?

Yes

- Repair the DF Signal Cable for an open circuit.
- Perform BODY VERIFICATION TEST - VER 1.Verification Tests

No

- Go To 3

3. AUXILIARY ELECTRICAL HEATER MODULE (AEHM) ECU RESET
The Auxiliary Electrical Heater Module (AEHM) is reporting internal errors.
Using the scan tool, perform ECU Reset on the Auxiliary Electrical Heater Module (AEHM).
Cycle the ignition off and back on.
With the scan tool, read AEHM DTC's.
Is this DTC active?

Yes

- Replace the Auxiliary Electrical Heater Module (AEHM).
- Perform BODY VERIFICATION TEST - VER 1.Verification Tests

No

- Test Complete.