No Response From HVAC (A/C Heater Control Module)

NO RESPONSE FROM HVAC (A/C HEATER CONTROL)





For a complete wiring diagram, refer to the Wiring Information.






1. TEST FOR INTERMITTENT CONDITION

NOTE: Check for any TSB(s) related to the condition. If a TSB applies, perform the procedure outlined in the TSB before continuing.

1. Turn the ignition on.

NOTE: Ensure the IOD fuse is installed and battery voltage is between 10.0 and 16.0 volts.

2. With the scan tool, select ECU View.

NOTE: A red "X" will be next to the module that is not communicating, indicating that the module is not active on the Bus network. A green check indicates that the module is active on the Bus network.

Does the scan tool display a red "X" next to the module?

Yes

- Go To 2

No

- Test complete, the condition or conditions that originally set this DTC are not present at this time. Using the wiring diagrams as a guide, check all related splices and connectors for signs of water intrusion, corrosion, pushed out or bent terminals, and correct pin tension.

2. (Z903) GROUND CIRCUIT OPEN




1. Turn the ignition off.
2. Disconnect the A/C Heater Control C1 harness connector.
3. Using a 12-volt test light connected to 12-volts check the (Z903) Ground circuit.

Does the test light illuminate brightly?

Yes

- Go To 3

No

- Repair the open in the (Z903) Ground circuit.
- Perform the BODY VERIFICATION TEST. Body Verification Test.

3. (A417) FUSED B+ (I.O.D.) CIRCUIT OPEN OR SHORTED




1. Using a 12-volt test light connected to ground, check the (A417) Fused B+ (I.O.D.) circuit.

Does the test light illuminate brightly?

Yes

- Go To 4

No

- Repair the open or short in the (A417) Fused B+ (I.O.D.) circuit.
- Perform the BODY VERIFICATION TEST. Body Verification Test.

4. (F929) FUSED IGNITION SWITCH OUTPUT (RUN) CIRCUIT OPEN OR SHORTED




1. Turn the ignition on.
2. Using a 12-volt test light connected to ground, check the (F929) Fused Ignition Switch Output (RUN) circuit.

Does the test light illuminate brightly?

Yes

- Go To 5

No

- Repair the open or short in the (F929) Fused Ignition Switch Output (RUN) circuit.
- Perform the BODY VERIFICATION TEST. Body Verification Test.

5. (D55) AND (D54) CAN B BUS CIRCUITS OPEN





NOTE: One open circuit will not cause this condition.

1. Measure the voltage between ground and the (D54) CAN B Bus (-) circuit.
2. Measure the voltage between ground and the (D55) CAN B Bus (+) circuit.

Is there any voltage present on either circuit?

Yes

- Replace the Heating, Ventilation and Air Conditioning Control Head.
- Perform the BODY VERIFICATION TEST. Body Verification Test.

No

- Repair the open in the (D55) and (D54) CAN B Bus circuits. Inspect the connector for damage.
- Perform the BODY VERIFICATION TEST. Body Verification Test.