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

*NO RESPONSE FROM A/C HEATER CONTROL (MTC) MODULE





For a complete wiring diagram Consult Diagrams/Electrical.





Diagnostic Test

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.

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. (Z24) GROUND CIRCUIT OPEN




Turn the ignition off.
Disconnect the A/C Heater Control (MTC) Module C1 harness connector.
Using a 12-volt test light connected to 12-volts, probe the (Z24) ground circuit.
Does the test light illuminate brightly?

Yes

- Go To 3

No

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

3. (F504) FUSED RUN RELAY OUTPUT CIRCUIT OPEN




Turn the ignition on.
Using a 12-volt test light connected to ground, probe the (F504) Fused Run Relay Output circuit.
Does the test light illuminate brightly?

Yes

- Go To 4

No

- Repair the (F504) Fused Run Relay Output circuit for an open.
- Perform the BODY VERIFICATION TEST - VER 1. Body Verification Test.

4. (D25) PCI BUS CIRCUIT OPEN




Turn the ignition off.
Disconnect the negative battery cable.
Disconnect the scan tool from the DLC connector.
Measure the resistance of the (D25) PCI Bus circuit between the A/C Heater Control (MTC) C1 harness connector and the DLC connector.
Is the resistance below 5.0 ohms?

Yes

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

No

- Repair the (D25) PCI Bus circuit for an open.
- Perform the BODY VERIFICATION TEST - VER 1. Body Verification Test.