P1101

P1101-HCM/PCM COMMUNICATION PERFORMANCE

For a complete wiring diagram, refer to the Wiring Information Electrical Diagrams.

Theory of Operation

The Electronic Air Conditioner (EAC) module communicates to the Front Control Module (FCM) through the CAN C BUS and then transmits the information over the CAN B BUS to the A/C Heater Control module. This DTC will set if communication the signal is not available or timed out between the EAC and the HVAC modules.

- When Monitored:
Continuously with the ignition on.

- Set Condition:
The EAC signal is not available or lost continuously for the period of 10 seconds. If the A/C Heater Control detects a valid EAC signal for the period of 10 seconds, the DTC will change from active to stored and will stay stored for 100 ignition cycles before being cleared.
NOTE: To check communication: in manual mode, press the A/C button (snowflake) to ON and set blower on high blower. Ambient temperature on the overhead display should read above 0.0° C (32° F). Normal A/C compressor speed listed under HVAC should show the target and actual speed matching.





Always perform the HVAC Pre-Diagnostic Troubleshooting procedure before proceeding. Initial Inspection and Diagnostic Overview.

1. CHECK IF DTC IS ACTIVE

WARNING: On vehicles equipped with the high voltage system, you must thoroughly read and follow all High Voltage Safety procedures. In addition, before performing any diagnostic or service procedure near a high voltage component, you must perform the High Voltage Power Down. Failure to follow these instructions may result in possible serious or fatal injury

1. Ignition on, engine not running.
2. With the scan tool, read HVAC DTCs.

Is this DTC active?

Yes

- Go To 2

No

- Go To 5

2. CHECK IF FCM DTCS ARE PRESENT
1. With the scan tool read Front Control Module (FCM) DTCs.

Are there any FCM BUS DTCs present?

Yes

- Testing and Inspection Perform the appropriate diagnostic procedure.
- Perform the HVAC VERIFICATION TEST. HVAC Verification Test.

No

- Go To 3

3. CHECK FOR OTHER HVAC DTCS
1. With the scan tool, read HVAC DTCs.

Are there any other HVAC BUS communication DTCs present?

Yes

- Testing and Inspection Perform the appropriate diagnostic procedure.

No

- Go To 4

4. CHECK FOR COMMUNICATION WITH EAC
1. With the scan tool, check if there is communication with the Electronic Air Conditioner (EAC) module.

Is there communication with the EAC module?

Yes

- Replace and program the A/C Heater Control.
- Perform the HVAC VERIFICATION TEST. HVAC Verification Test.

No

- No Response From EAC Perform the diagnostic procedure for NO RESPONSE FROM EAC.

5. CHECK THE WIRING AND CONNECTORS
1. The conditions necessary to set the DTC are not present at this time.
2. With the scan tool, check the Environmental Data to help identify the conditions in which the DTC was set.
3. Using the schematics as a guide, inspect the wiring and connectors specific to this circuit.
4. Check for an intermittent condition by inspecting the related wiring harness for chafed, pierced, pinched, partially broken wires.
5. Check the connectors for broken, bent, pushed out, spread, corroded, or contaminated terminals.
6. Wiggle the wiring and connectors while checking for shorted and open circuits.

Were there any problems found?

Yes

- Repair as necessary.
- Perform the HVAC VERIFICATION TEST. HVAC Verification Test.

No

- Test complete.