Coolant Temperature Message Missing (ATC)

COOLANT TEMPERATURE MESSAGE MISSING (ATC)

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 the Coolant Temperature message from the Powertrain Control Module (PCM) for more than 10 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

- It is possible that a technician may not have erased the DTC following a repair. If possible, verify if the vehicle was recently in for this type of service. Otherwise, using the schematics as a guide, check the A/C Heater Control, the BCM, and the PCM pins, terminals, and connectors for corrosion, damage, and terminal push out. Pay particular attention to all Communication, Power, & Ground circuits.
- 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.