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

NO RESPONSE FROM HVAC (A/C HEATER CONTROL MODULE)
















1. TEST FOR INTERMITTENT CONDITION
1. Turn the ignition on.

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

2. Using 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

- The no response condition is not present at this time. Using the wiring diagram/schematic as a guide, inspect the wiring for chafed, pierced, pinched, and partially broken wires and the wiring harness connectors for broken, bent, pushed out, and corroded terminals.

2. (A417) FUSED B(+) CIRCUIT OPEN OR SHORTED




1. Turn the ignition off.
2. Disconnect the HVAC harness connectors.
3. Using a 12-volt test light connected to ground, check the (A417) Fused B(+) circuit.

Does the test light illuminate brightly for each circuit?

Yes

- Go To 3

No

- Repair the (A417) Fused B(+) circuit for an open or short.
- Perform the BODY VERIFICATION TEST. Body Verification Test.

3. (Z906) GROUND CIRCUIT OPEN




1. Using a 12-volt test light connected to 12-volts, check the (Z906) ground circuit.

Does the test light illuminate brightly for each circuit?

Yes

- Go To 4

No

- Repair the (Z906) ground circuit for an open.
- Perform the BODY VERIFICATION TEST. Body Verification Test.

4. (F921) FUSED RUN RELAY OUTPUT CIRCUIT OPEN OR SHORTED




1. Turn the ignition on.
2. Using a 12-volt test light connected to ground, check the (F921) Fused Run Relay Output circuit.

Does the test light illuminate brightly?

Yes

- Go To 5

No

- Repair the (F921) Fused Run Relay Output circuit for an open or short.
- Perform the BODY VERIFICATION TEST. Body Verification Test.

5. (D265) OR (D264) CAN INTERIOR BUS (125K) CIRCUIT OPEN




1. Measure the resistance of the (D264) CAN Interior Bus (-) (125K) circuit between the TIPM C7 harness connector and the HVAC harness connector.
2. Measure the resistance of the (D265) CAN Interior Bus (+) (125K) circuit between the TIPM C7 harness connector and the HVAC harness connector.

Is resistance below 5.0 Ohms on both circuits?

Yes

- Replace the A/C Heater Control Module.
- Perform the BODY VERIFICATION TEST. Body Verification Test.

No

- Repair the (D265) or (D264) CAN C Interior Bus (125K) circuit for an open. Inspect the connector for damage.
- Perform the BODY VERIFICATION TEST. Body Verification Test.