PCM Communication Failure (MTC)

PCM COMMUNICATION FAILURE (MTC)

For a complete wiring diagram Consult Diagrams/Electrical

- When Monitored:
With the ignition on.

- Set Condition:
If the A/C Heater Control fails to receive any messages from the Powertrain Control Module (PCM) for more than 5 seconds.





Diagnostic Test

1. VERIFY DTC IS ACTIVE
Turn the ignition on.
With the scan tool, read HVAC DTCs.
Does the scan tool display this DTC as active?

Yes

- Go To 2

No

- The condition that caused this symptom is currently not present. Check for an intermittent condition by inspecting the related wiring harness for chafed, pierced, pinched, and partially broken wires. Also, inspect the related connectors for broken, bent, pushed out, spread, corroded, or contaminated terminals. Repair as necessary.
- Perform BODY VERIFICATION TEST - VER 1. Body Verification Test.

2. VERIFY BCM & PCM ARE ACTIVE ON THE BUS
With the scan tool, verify that the BCM and PCM are active on the Bus.
Are the BCM and PCM active on the Bus?

Yes

- Go To 3

No

- Communications - Verbose Codes for No Response related diagnostic procedures.

3. CHECK FOR BCM & PCM DTCs
With the scan tool, read BCM and PCM DTCs.
Are any DTCs present?

Yes

- Diagnose and repair the DTC(s).
- Perform BODY VERIFICATION TEST - VER 1. Body Verification Test.

No

- Go To 4

4. CHECK FOR ADDITIONAL COMMUNICATION RELATED DTCs
With the scan tool, select Network View and select Advanced.
Is there more than one module with active DTCs "Logged Against" the BCM?

Yes

- Using the schematics as a guide, check the BCM pins, terminals, and connectors for corrosion, damage, and terminal push out. Pay particular attention to all Communication, Power, and Ground circuits. If no problems are found, replace and program the BCM.
- Perform BODY VERIFICATION TEST - VER 1. Body Verification Test.

No

- Go To 5

5. CHECK FOR ADDITIONAL COMMUNICATION RELATED DTCs
With the scan tool, select Network View and select Advanced.
Is there more than one module with active DTCs "Logged Against" the PCM?

Yes

- Using the schematics as a guide, check the PCM pins, terminals, and connectors for corrosion, damage, and terminal push out. Pay particular attention to all Communication, Power, and Ground circuits. If no problems are found, replace and program the PCM.
- Perform BODY VERIFICATION TEST - VER 1. Body Verification Test.

No

- Using the schematics as a guide, check the A/C Heater Control pins, terminals, and connectors for corrosion, damage, and terminal push out. Pay particular attention to all Communication, Power, and Ground circuits. If no problems are found, replace the A/C Heater Control.
- Perform BODY VERIFICATION TEST - VER 1. Body Verification Test.