Pinpoint Test T: The Heated Seat Does Not Operate Correctly - Seat Does Heat But the Heated Seat Indicator Does Not Illuminate

Seats

Pinpoint Test T: The Heated Seat Does Not Operate Correctly - Seat Does Heat But the Heated Seat Indicator Does Not Illuminate When Pressed

Refer to Wiring Diagram Set 119 (Fusion/Milan/MKZ, Fusion Hybrid, Milan Hybrid, MKZ Hybrid), Climate Controlled Seats for schematic and connector information. Diagrams By Number

Normal Operation

When the heated seat module is commanded ON, voltage is supplied from the heated seat module to the HVAC module on the low/high heat mode indicator circuits. When voltage is not supplied from the heated seat module, none of the indicators illuminate.

This pinpoint test is intended to diagnose the following:
- Wiring, terminals or connectors
- Heated seat module
- HVAC module
- Front Controls Interface Module (FCIM)

PINPOINT TEST T: THE HEATED SEAT DOES NOT OPERATE CORRECTLY - SEAT DOES HEAT BUT THE HEATED SEAT INDICATOR DOES NOT ILLUMINATE WHEN PRESSED

NOTE: If a seat equipped with a seat mounted side air bag is being serviced, the Supplemental Restraint System (SRS) must be depowered. Refer to Supplemental Restraint System Supplemental Restraint System (SRS) Depowering and Repowering.

NOTE: The air bag warning lamp illuminates when the Restraints Control Module (RCM) fuse is removed and the ignition switch is ON. This is normal operation and does not indicate an SRS fault.

NOTE: The SRS must be fully operational and free of faults before releasing the vehicle to the customer.

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T1 CHECK INDICATOR CIRCUITS FOR A SHORT TO GROUND

- Ignition OFF.
- Depower the SRS. Refer to Supplemental Restraint System (SRS) Depowering and Repowering in the General Procedures portion of Supplemental Restraint System Supplemental Restraint System (SRS) Depowering and Repowering.
- Disconnect: Passenger Seat Side Air Bag Module C313.
- Disconnect: HVAC Module C2356B.
- Disconnect: Heated Seat Module C3304A.
- For driver seat, measure the resistance between:
- HVAC module C2356B-7, circuit CHS04 (YE/GY), harness side and ground.
- HVAC module C2356B-8, circuit CHS13 (VT/BN), harness side and ground.

- For passenger seat, measure the resistance between:
- HVAC module C2356B-4, circuit CHS09 (GY), harness side and ground.
- HVAC module C2356B-5, circuit CHS14 (GN), harness side and ground.

- Are the resistances greater than 10,000 ohms?

Yes
GO to T2.

No
REPAIR the circuit(s). TEST the system for normal operation.

DISCONNECT the battery ground cable. CONNECT passenger seat side air bag module C313. REPOWER the SRS. REFER to Supplemental Restraint System Supplemental Restraint System (SRS) Depowering and Repowering.

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T2 CHECK INDICATOR CIRCUITS FOR AN OPEN

- For driver seat, measure the resistance between:
- HVAC module C2356B-7, circuit CHS04 (YE/GY), harness side and heated seat module C3304A-4, circuit CHS04 (YE/GY), harness side.
- HVAC module C2356B-8, circuit CHS13 (VT/BN), harness side and heated seat module C3304A-5, circuit CHS13 (VT/BN), harness side.

- For passenger seat, measure the resistance between:
- HVAC module C2356B-4, circuit CHS09 (GY), harness side and heated seat module C3304A-10, circuit CHS09 (GY), harness side.
- HVAC module C2356B-5, circuit CHS14 (GN), harness side and heated seat module C3304A-11, circuit CHS14 (GN), harness side.

- Are the resistances less than 5 ohms?

Yes
For driver seat, GO to T3.

For passenger seat, GO to T4.

No
REPAIR the circuit(s). TEST the system for normal operation.

DISCONNECT the battery ground cable. CONNECT passenger seat side air bag module C313. REPOWER the SRS. REFER to Supplemental Restraint System Supplemental Restraint System (SRS) Depowering and Repowering.

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T3 CHECK THE HEATED SEAT MODULE INDICATOR CIRCUIT OUTPUT

- Connect: HVAC Module C2356B.
- Connect: Heated Seat Module C3304A.
- Start the engine.
- NOTE: The following measurement must be taken by back-probing heated seat module C3304A.
- NOTE: There should be no voltage on circuit CHS04 (YE/GY) when the driver seat side of the heated seat module is off. When the heated seat module is commanded on, voltage on circuit CHS04 (YE/GY) should drop momentarily each time the driver heated seat control button is pressed.
- Measure the voltage between heated seat module C3304A-4, circuit CHS04 (YE/GY), harness side and ground by back-probing heated seat module C3304A-4. Press the driver heated seat control button and note the voltage.

- Is there less than 1 volt when the heated seat module is off and greater than 10 volts when the driver heated seat module is in low or high mode?

Yes
For vehicles without navigation, INSTALL a new HVAC module.

For vehicles with navigation, INSTALL a new FCIM. REFER to Information and Entertainment Systems Service and Repair.

TEST the system for normal operation.

DISCONNECT the battery ground cable.

CONNECT passenger seat side air bag module C313.

REPOWER the SRS. REFER to Supplemental Restraint System Supplemental Restraint System (SRS) Depowering and Repowering.

No
INSTALL a new heated seat module. REFER to Heated Seat Module Heated Seat Module.

TEST the system for normal operation.

DISCONNECT the battery ground cable.

CONNECT passenger seat side air bag module C313.

REPOWER the SRS. REFER to Supplemental Restraint System Supplemental Restraint System (SRS) Depowering and Repowering.

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T4 CHECK THE HEATED SEAT MODULE INDICATOR CIRCUIT OUTPUT

- Connect: HVAC Module C2356B.
- Connect: Heated Seat Module C3304A.
- Start the engine.
- NOTE: The following measurement must be taken by back-probing heated seat module C3304A.
- NOTE: There should be no voltage on circuit CHS09 (GY) when the passenger seat side of the heated seat module is off. When the heated seat module is commanded on, voltage on circuit CHS09 (GY) should drop momentarily each time the passenger heated seat control button is pressed.
- Measure the voltage between heated seat module C3304A-10, circuit CHS09 (GY), harness side and ground by back-probing heated seat module C3304A-10. Press the passenger heated seat control button and note the voltage.