Diagnostic Routine M

Diagnostic Routine M

Diagnostic Overview

The Air Conditioning (AC) Is Always On - AC Mode Always Commanded On

Refer to Wiring Diagram Set 54 for schematic and connector information Electrical Diagrams.

Normal Operation and Fault Conditions

When the A/C (Air Conditioning) is requested, the FCIM (Front Controls Interface Module) sends the button press message over the I-CAN (Infotainment Controller Area Network) to the IPC (Instrument Panel Cluster). The IPC (Instrument Panel Cluster) then sends the button press message to BCM (Body Control Module) over the HS-CAN (High Speed Controller Area Network). The BCM (Body Control Module) then sends the button press message to the HVAC (Heating, Ventilation, and Air Conditioning) module over the MS-CAN (Medium Speed Controller Area Network). Lastly the HVAC (Heating, Ventilation, and Air Conditioning) module sends an A/C (Air Conditioning) request message through the MS-CAN (Medium Speed Controller Area Network) to the BCM (Body Control Module) and the BCM (Body Control Module) sends the A/C (Air Conditioning) request through the HS-CAN (High Speed Controller Area Network) to the PCM (Powertrain Control Module).

REFER to Control System Logic

DTC Fault Trigger Conditions






Pinpoint Test

1. CHECK THE A/C (Air Conditioning) SWITCH STATUS (CC_SW_AC) PID (Parameter Identification) WITH THE A/C (Air Conditioning) OFF

1. Ignition ON.

2. Using a scan tool, view FCIM (Front Controls Interface Module) PIDs (Parameter Identifications).

3. Monitor the FCIM (Front Controls Interface Module) PID (Parameter Identification) CC_SW_AC.

4. Select panel press and release the A/C (Air Conditioning) button (indicator off) on the HVAC (Heating, Ventilation, and Air Conditioning) controls.

Does the PID (Parameter Identification) read Active when pressed and Inactive when released?








2. CHECK THE A/C (Air Conditioning) REQUEST SIGNAL (AC_REQ) PID (Parameter Identification) WITH THE A/C OFF

1. Using a scan tool, view PCM (Powertrain Control Module) PIDs (Parameter Identifications).

2. Deactivate the A/C (Air Conditioning) using the HVAC (Heating, Ventilation, and Air Conditioning) controls.

3. Monitor the PCM (Powertrain Control Module) PID (Parameter Identification) AC_REQ.

Does the PID (Parameter Identification) read OFF?








3. CHECK FOR CORRECT HVAC (Heating, Ventilation, and Air Conditioning) MODULE OPERATION

1. Ignition OFF.

2. Disconnect and inspect all HVAC (Heating, Ventilation, and Air Conditioning) module connectors.

3. Repair:

- corrosion (install new connector or terminals- clean module pins)
- damaged or bent pins- install new terminals/pins
- pushed-out pins- install new pins as necessary

4. Reconnect the HVAC (Heating, Ventilation, and Air Conditioning) module connectors. Make sure they seat and latch correctly.

5. Operate the system and determine if the concern is still present.

Is the concern still present?








4. CHECK FOR CORRECT PCM (Powertrain Control Module) OPERATION

1. Ignition OFF.

2. Disconnect and inspect all PCM (Powertrain Control Module) connectors.

3. Repair:

- corrosion (install new connector or terminals- clean module pins)
- damaged or bent pins- install new terminals/pins
- pushed-out pins- install new pins as necessary

4. Reconnect the PCM (Powertrain Control Module) connectors. Make sure they seat and latch correctly.

5. Operate the system and determine if the concern is still present.

Is the concern still present?