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

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






For a complete wiring diagram refer to Diagrams/Electrical.






Diagnostic Test


1. TEST FOR INTERMITTENT CONDITION

Turn the ignition on.

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

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

- 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. (A919) FUSED B(+) CIRCUIT OPEN OR SHORTED





Turn the ignition off.

Disconnect the A/C Heater Control C1 harness connector.

Using a 12-volt test light connected to ground, check the (A919) Fused B(+) circuit.

Does the test light illuminate brightly?

Yes

- Go To 3

No

- Repair the (A919) Fused B(+) circuit for an open or short.
- Perform BODY VERIFICATION TEST - VER 1. Body Verification Test

3. (F504) FUSED IGNITION SWITCH OUTPUT CIRCUIT OPEN OR SHORTED





Turn the ignition on.

Using a 12-volt test light connected to ground, check the (F504) Fused Ignition Switch Output circuit.

Does the test light illuminate brightly?

Yes

- Go To 4

No

- Repair the (F504) Fused Ignition Switch Output for an open or short.
- Perform BODY VERIFICATION TEST - VER 1. Body Verification Test

4. (Z24) GROUND CIRCUIT OPEN





Using a 12-volt test light connected to 12-volts, check the (Z24) ground circuit.

Does the test light illuminate brightly?

Yes

- Go To 5

No

- Repair the (Z24) ground circuit for an open.
- Perform BODY VERIFICATION TEST - VER 1. Body Verification Test

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






NOTE: One open circuit will not cause this condition.

Measure the voltage between the (D54) CAN B Bus (-) circuit and ground.

Measure the voltage between the (D55) CAN B Bus (+) circuit and ground.

Is there any voltage present on either circuit?

Yes

- Replace the A/C Heater Control.
- Perform BODY VERIFICATION TEST - VER 1. Body Verification Test

No

- Repair the (D55) and (D54) CAN B Bus circuits for an open. Inspect the connector for damage.
- Perform BODY VERIFICATION TEST - VER 1. Body Verification Test