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

Seats

Pinpoint Tests

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), 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 indicator circuits. In high heat mode, the heated seat module supplies voltage on circuits CHS04 and CHS13 for the driver seat and on circuits CHS09 and CHS14 for the passenger seat. In low heat mode, the heated seat module supplies voltage on circuit CHS04 for the driver seat and on CHS09 for the passenger seat. 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: The air bag warning indicator illuminates when the correct Restraints Control Module (RCM) fuse is removed and the ignition switch is ON.

NOTE: The Supplemental Restraint System (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 Restraint Systems.
- 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 Restraint Systems.

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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 Restraint Systems.

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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 Accessories and Optional Equipment.

TEST the system for normal operation.

DISCONNECT the battery ground cable.

CONNECT passenger seat side air bag module C313.

REPOWER the SRS. REFER to Restraint Systems.

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 Restraint Systems.

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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.