No Response From HVAC (A/C Heater Control - ATC)

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

No Response From HVAC (A/C Heater Control - ATC Only):

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.

Q: 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. (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.

Q: Does the test light illuminate brightly?

YES: Go To 3
NO: Repair the (A114) Fused B(+) circuit for an open or short. Perform BODY VERIFICATION TEST - VER 1. Body Verification Test




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.

Q: Does the test light illuminate brightly?

YES: Go To 4
NO: Repair the (F921) Fused Run Relay Output for an open or short. Perform BODY VERIFICATION TEST - VER 1. Body Verification Test




4. (Z906) GROUND CIRCUIT OPEN

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

Q: Does the test light illuminate brightly?

YES: Go To 5
NO: Repair the (Z906) 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.

Q: 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