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Pinpoint Test J: The Air Conditioning (A/C) is Always On - A/C Mode Always Commanded ON




Climate Control System

Pinpoint Test J: The Air Conditioning (A/C) is Always On - A/C Mode Always Commanded ON

Refer to Wiring Diagrams Set 54, Manual Climate Control System for schematic and connector information. Electrical Diagrams

Normal Operation

When the A/C switch is pressed, a ground is provided to the Instrument Cluster (IC) A/C switch input. When the IC (Instrument Cluster) receives this ground, it sends an A/C request message through the High Speed Controller Area Network (HS-CAN) bus to the PCM and an A/C request message through the Medium Speed Controller Area Network (MS-CAN) to the Generic Electronic Module (GEM).

When the GEM (Generic Electronic Module) receives the A/C request message from the IC (Instrument Cluster), it provides a ground for the A/C switch indicator. Voltage is provided to the indicator. When the GEM (Generic Electronic Module) provides ground, the indicator illuminates.

- DTC B1262 (Servo Motor Defrost Circuit Failure)- The DTC sets when the GEM (Generic Electronic Module) detects a continuous ground on the DEFROST mode switch input from the function selector switch to the GEM (Generic Electronic Module), indicating a direct short to ground on the circuit.

- DTC P2175 (A/C Request Signal Circuit Short to Ground)- The DTC sets when the IC (Instrument Cluster) detects a continuous ground on the A/C switch input to the IC (Instrument Cluster), indicating a direct short to ground on the circuit.

This pinpoint test is intended to diagnose the following:

- Wiring, terminals or connectors

- A/C switch

- Function selector switch

- GEM (Generic Electronic Module)

- IC (Instrument Cluster)

- PCM

PINPOINT TEST J : THE AIR CONDITIONING (A/C) IS ALWAYS ON - A/C MODE ALWAYS COMMANDED ON

NOTE: Before carrying out the following test, diagnose any PCM, GEM (Generic Electronic Module) or IC (Instrument Cluster) DTCs.

NOTE: Before carrying out the following test, check that the A/C system pressure is above 290 kPa (42 psi). If the pressure is below 290 kPa (42 psi), refer to Fluorescent Dye Leak Detection Fluorescent Dye Leak Detection.

J1 CHECK A/C INDICATOR OPERATION

- Start the engine.

- With the engine running, place the function selector switch to the PANEL position.

- Place the blower motor switch to lowest position.

- Press the A/C switch multiple times.

Does the A/C indicator turn ON and OFF?

Yes
GO to J5.

No
GO to J2.

J2 CHECK THE CLIMATE CONTROL / DEFROSTER (DEFROST_SW) GEM (Generic Electronic Module) PID

- Enter the following diagnostic mode on the scan tool: GEM (Generic Electronic Module) DataLogger.

- With the engine running, place the function selector switch to the PANEL position monitoring the DEFROST_SW GEM (Generic Electronic Module) PID.

Does the DEFROST_SW GEM (Generic Electronic Module) PID read INACTIVE?

Yes
GO to J11.

No
GO to J3.

J3 CHECK THE CLIMATE CONTROL / DEFROSTER (DEFROST_SW) GEM (Generic Electronic Module) PID WITH THE FUNCTION SELECTOR SWITCH DISCONNECTED

- Ignition OFF.

- Disconnect: Function Selector Switch C294.

- Start the engine.

- Enter the following diagnostic mode on the scan tool: GEM (Generic Electronic Module) DataLogger.

- Observe the DEFROST_SW GEM (Generic Electronic Module) PID.

Does the DEFROST_SW GEM (Generic Electronic Module) PID read INACTIVE?

Yes
INSTALL a new function selector switch. TEST the system for normal operation.

No
GO to J4.

J4 CHECK THE FUNCTION SELECTOR SWITCH INPUT CIRCUIT FOR A SHORT TO GROUND

- Ignition OFF.

- Disconnect: GEM (Generic Electronic Module) C201C.

- Measure the resistance between function selector switch C294-3, circuit 91S-FA20 (BK/YE), harness side and ground.





Is the resistance greater than 10,000 ohms?

Yes
GO to J9.

No
REPAIR circuit 91S-FA20 (BK/YE) for a short to ground. TEST the system for normal operation.

J5 CHECK AIR CONDITIONING SWITCH (AC_SW) IC (Instrument Cluster) PID WITH THE A/C OFF

- Enter the following diagnostic mode on the scan tool: Instrument Cluster (IC) DataLogger.

- Press the A/C switch until the A/C indicator is OFF and monitor the AC_SW IC (Instrument Cluster) PID.

Does the AC_SW IC (Instrument Cluster) PID read NO?

Yes
GO to J8.

No
GO to J6.

J6 CHECK AIR CONDITIONING SWITCH (AC_SW) IC (Instrument Cluster) PID WITH THE A/C SWITCH DISCONNECTED

- Ignition OFF.

- Disconnect: A/C Switch C2891.

- Start the engine.

- Enter the following diagnostic mode on the scan tool: IC (Instrument Cluster) DataLogger.

- Observe the AC_SW IC (Instrument Cluster) PID.

Does the AC_SW IC (Instrument Cluster) PID read NO?

Yes
INSTALL a new A/C switch. TEST the system for normal operation.

No
GO to J7.

J7 CHECK THE A/C SWITCH INPUT CIRCUIT FOR A SHORT TO GROUND

- Ignition OFF.

- Disconnect: IC (Instrument Cluster) C220A.

- Measure the resistance between A/C switch C2891-6, circuit 15S-FA13 (GN/RD), harness side and ground.





Is the resistance greater than 10,000 ohms?

Yes
GO to J10.

No
REPAIR circuit 15S-FA13 (GN/RD) for a short to ground. TEST the system for normal operation.

J8 CHECK THE A/C SWITCH INDICATOR SWITCHED GROUND CIRCUIT FOR A SHORT TO VOLTAGE

- Ignition OFF.

- Disconnect: A/C Switch C2891.

- Disconnect: GEM (Generic Electronic Module) C201C.

- Ignition ON.

- Measure the voltage between A/C switch C2891-5, circuit 91S-FA9 (BK/GN), harness side and ground.





Is the voltage greater than 10 volts?

Yes
REPAIR circuit 91S-FA9 (BK/GN) for a short to voltage. TEST the system for normal operation.

No
GO to J9.

J9 CHECK THE GEM (Generic Electronic Module) CONNECTION

- Clear the DTCs.

- Disconnect all the GEM (Generic Electronic Module) connectors.

- Check for:
- corrosion

- pushed-out pins

- incorrectly seated connector


- Connect and correctly seat all the GEM (Generic Electronic Module) connectors.

- Operate the system.

Does the concern return?

Yes
INSTALL a new GEM (Generic Electronic Module). TEST the system for normal operation.

No
The system is operating correctly at this time. The concern may have been caused by a loose or corroded connector.

J10 CHECK THE IC (Instrument Cluster) CONNECTION

- Clear the DTCs.

- Disconnect all the IC (Instrument Cluster) connectors.

- Check for:
- corrosion

- pushed-out pins

- incorrectly seated connector


- Connect and correctly seat all the IC (Instrument Cluster) connectors.

- Operate the system.

Does the concern return?

Yes
INSTALL a new IC (Instrument Cluster). TEST the system for normal operation.

No
The system is operating correctly at this time. The concern may have been caused by a loose or corroded connector.

J11 CHECK THE PCM CONNECTION

- Clear the DTCs.

- Disconnect all the PCM connectors.

- Check for:
- corrosion

- pushed-out pins

- incorrectly seated connector


- Connect and correctly seat all the PCM connectors.

- Operate the system.

Does the concern return?

Yes
INSTALL a new PCM. TEST the system for normal operation.

No
The system is operating correctly at this time. The concern may have been caused by a loose or corroded connector.

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