Diagnostic Routine M

Diagnostic Routine M

Diagnostic Overview

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

Normal Operation and Fault Conditions

REFER to Controls and Compressor Cycling

DTC Fault Trigger Conditions





BCM (Body Control Module) DTC Fault Trigger Conditions






Pinpoint Test

1. PERFORM BCM (Body Control Module) SELF-TEST

1. Ignition ON.

2. Using a scan tool, perform BCM (Body Control Module) self-test.

Is DTC (Diagnostic Trouble Code) B101E:23 received?






2. PERFORM BCM (Body Control Module) SELF-TEST WITH THE HVAC (Heating, Ventilation, and Air Conditioning) MODULE DISCONNECTED

1. Ignition OFF.

2. Disconnect: HVAC (Heating, Ventilation, and Air Conditioning) Module C2357A.

3. Ignition ON.

4. Using a scan tool, perform BCM (Body Control Module) self-test.

Is DTC (Diagnostic Trouble Code) B101E:23 received?






3. CHECK THE A/C (Air Conditioning) REQUEST CIRCUIT BETWEEN THE HVAC (Heating, Ventilation, and Air Conditioning) MODULE AND THE BCM (Body Control Module) FOR A SHORT TO GROUND

1. Ignition OFF.

2. Disconnect: BCM (Body Control Module) C2280C.

3. Measure:





Is the resistance greater than 10,000 ohms?






4. CHECK THE AIR CONDITIONING REQUEST SIGNAL (AC_REQ) PID (Parameter Identification)

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

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

3. Select vent on the HVAC (Heating, Ventilation, and Air Conditioning) module and toggle the A/C on and off.

Does the PID (Parameter Identification) correspond with the switch position?






5. CHECK THE AIR CONDITIONING REQUEST SIGNAL (AC_REQ) PID (Parameter Identification) WITH THE HVAC (Heating, Ventilation, and Air Conditioning) MODULE DISCONNECTED

1. Ignition OFF.

2. Disconnect: HVAC (Heating, Ventilation, and Air Conditioning) Module C2357A.

3. NOTE: Do not connect the jumper to ground until step G.
Connect a fused jumper wire:





4. Ignition ON.

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

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

7. Momentarily touch the jumper to ground.

Does the PID (Parameter Identification) switch states when the jumper touched ground?






6. CHECK THE A/C (Air Conditioning) REQUEST CIRCUIT BETWEEN THE HVAC (Heating, Ventilation, and Air Conditioning) MODULE AND THE BCM (Body Control Module) FOR AN OPEN

1. Ignition OFF.

2. Disconnect: BCM (Body Control Module) C2280C.

3. Measure:





Is the resistance greater than 10,000 ohms?






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

1. Ignition OFF.

2. Disconnect and inspect all the 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?






8. CHECK FOR CORRECT BCM (Body Control Module) OPERATION

1. Ignition OFF.

2. Disconnect and inspect the BCM (Body 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 BCM (Body 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?