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

For a complete wiring diagram Refer to Section 8W.

Possible Causes

(A114) FUSED B(+) CIRCUIT OPEN OR SHORTED

(F921) FUSED RUN RELAY OUTPUT CIRCUIT OPEN OR SHORTED

(Z906) GROUND CIRCUIT OPEN

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

A/C HEATER CONTROL

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

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. (A114) 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 (A114) Fused B(+) circuit.

Does the test light illuminate brightly?

Yes

Go To 3

Repair the (A114) Fused B(+) circuit for an open or short.
Perform BODY VERIFICATION TEST – VER 1. (Refer to 8 - ELECTRICAL/ELECTRONIC CONTROL MODULES - STANDARD PROCEDURE).

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

Turn the ignition on.
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 4

Repair the (F921) Fused Run Relay Output for an open or short.
Perform BODY VERIFICATION TEST – VER 1. (Refer to 8 - ELECTRICAL/ELECTRONIC CONTROL MODULES - STANDARD PROCEDURE).

4. (Z906) GROUND CIRCUIT OPEN

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

Does the test light illuminate brightly?

Yes

Go To 5

Repair the (Z906) ground circuit for an open.
Perform BODY VERIFICATION TEST – VER 1. (Refer to 8 - ELECTRICAL/ELECTRONIC CONTROL MODULES - STANDARD PROCEDURE).

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 in accordance with the service information.

Perform BODY VERIFICATION TEST – VER 1. (Refer to 8 - ELECTRICAL/ELECTRONIC CONTROL MODULES - STANDARD PROCEDURE).

Repair the (D55) and (D54) CAN B Bus circuits for an open. Inspect the connector for damage.
Perform BODY VERIFICATION TEST – VER 1. (Refer to 8 - ELECTRICAL/ELECTRONIC CONTROL MODULES - STANDARD PROCEDURE).