Seating

Special Tool(s)

	Flex Probe Kit 105-R025D or equivalent
	Fluke 77-IV Digital Multimeter FLU77-4 or equivalent
	Vehicle Communication Module (VCM) and Integrated Diagnostic System (IDS) software with appropriate hardware, or equivalent scan tool

Principles of Operation

Power Seats

Each power seat uses a 6-way power seat track and 3 electric motors directly controlled by a seat-mounted, 6-way seat control switch for horizontal (forward/rearward), front height and rear height adjustment.

The power lumbar motor pulls and releases a cable in the lumbar assembly to move the backrest in and out.

The power seat motors are hardwired to the seat control and lumbar switches. The circuits are normally at ground through the seat control switch. An individual motor is switched to voltage and ground when a specific adjustment position is selected. Power seats operate independently from the ignition position.

Heated Seats

The heated seat switches and indicators are part of the Front Controls Interface Module (FCIM). The heated seat system operates independently from the other systems controlled by the FCIM and HVAC module.

When a heated seat button is pressed, the FCIM illuminates the heated seat indicator and transmits a system request message to the HVAC module on the module communication network. The HVAC module receives the message and provides ground to the driver or passenger heated seat relay coil circuit to operate the heated seat. The heated seat system can only operate if both modules are communicating correctly on the communication network and the engine is running.

The driver and passenger heated seat relays are located underneath the driver seat cushion frame. With the ignition ON, voltage is supplied from the Smart Junction Box (SJB) to each heated seat relay coil. Battery voltage is also supplied to the heated seat relay contacts (hot at all times). When energized, the heated seat relay coil closes the relay contact to supply battery voltage from the Battery Junction Box (BJB) to the cushion heater mat. The cushion and backrest heater mats are wired in series and each backrest heater mat is directly connected to ground to complete the electrical circuit to heat a seat.

Each cushion heater mat contains a thermostatic switch that closes when cold to complete the heater grid circuit and heat the seat. When hot, the thermostatic switch opens the heater grid circuit and allows the seat to cool. The heated seat indicator illuminates continuously while the thermostatic switch cycles open and closed. The thermostatic switch is serviceable only as part of a new heater mat.

The HVAC module monitors the heated seat relay coil ground circuits for an open, short to ground and short to voltage. If a circuit fault is detected, a DTC is set and the HVAC module disables the affected seat by removing circuit ground to the heated seat relay coil (refer to the HVAC Module DTC Chart in this section). The HVAC module also transmits a network communication message to the FCIM to deactivate the heated seat indicator. PIDs are available in the FCIM using the scan tool to verify heated seat switch operation.

The seat should be occupied to correctly test for normal operation. Temperature measuring devices do not provide an accurate method for testing heated seat operation as surface temperatures are subject to human and environmental characteristics. Correct testing requires heater mat resistance measurements which have tight tolerances affecting heat cycle time length.

The heated seat system does not time-out and will remain on until selected off or engine is off.

Inspection and Verification

1. Verify the customer concern by operating the power seat or heated seat functions.

2. Visually inspect for obvious signs of mechanical or electrical damage.
   
   

     Visual Inspection Chart

   Mechanical

   Electrical

   Switch(es) Seat tracks obstructed or damaged Recliner assembly damaged (backrest frame) Power lumbar assembly damaged Seat cushion or backrest trim cover damaged (heated seat heater mats)

   Smart Junction Box (SJB) fuse 43 (10A) (heated seats) Battery Junction Box (BJB) fuses: 16 (20) (heated seats) 32 (30A) (driver power seat and power lumbar) 31 (30A) (passenger power seat) Loose, corroded or damaged connectors Wiring harness Seat control switch Lumbar control switch Heated seat switch [part of Front Controls Interface Module (FCIM)] Heated seat relays Power seat motor assembly (seat track) Backrest or cushion heater mat FCIM HVAC module

   
   

3. If an obvious cause for an observed or reported concern is found, correct the cause (if possible) before proceeding to the next step.

4. If the concern is with the power seat, verify the symptom and GO to Symptom Chart .

5. NOTE: Make sure to use the latest scan tool software release.

   If the concern is with the heated seat and the cause is not visually evident, connect the scan tool to the Data Link Connector (DLC).

6. NOTE: The Vehicle Communication Module (VCM) LED prove out confirms power and ground from the DLC are provided to the VCM .

   If the scan tool does not communicate with the VCM :
   • check the VCM connection to the vehicle.
   • check the scan tool connection to the VCM .
   • refer to Section 418-00 , No Power To The Scan Tool, to diagnose no power to the scan tool.

7. If the scan tool does not communicate with the vehicle:
   • verify the ignition is ON.
   • verify the scan tool operation with a known good vehicle.
   • refer to Section 418-00 to diagnose no response from the PCM.

8. Carry out the network test.
   • If the scan tool responds with no communication for one or more modules, refer to Section 418-00 .
   • If the network test passes, retrieve and record on-demand and continuous memory DTCs.

9. Clear the continuous DTCs and carry out the self-test diagnostics for the HVAC module.

10. If the DTCs retrieved are related to the concern, go to HVAC Module DTC Chart. For all other DTCs, refer to Section 419-10 .

11. If no DTCs related to the concern are retrieved, GO to Symptom Chart .

DTC Chart

 HVAC Module DTC Chart

NOTE: This module utilizes a 5-character DTC followed by a 2-character failure type code. The failure type code provides information about specific fault conditions such as opens or shorts to ground. Continuous Memory Diagnostic Trouble Codes (CMDTCs) have an additional 2-character DTC status code suffix to assist in determining DTC history.

Symptom Chart

Pinpoint Tests

NOTICE: Use the correct probe adapter(s) from the Flex Probe Kit when making measurements. Failure to use the correct probe adapter(s) may damage the connector.

NOTICE: Most faults are due to connector and/or wiring concerns. Carry out a thorough inspection and verification before proceeding with the pinpoint test.

NOTE: The air bag warning indicator illuminates when the correct Restraints Control Module (RCM) fuse is removed and the ignition is ON.

NOTE: The Supplemental Restraint System (SRS) must be fully operational and free of faults before releasing the vehicle to the customer.

Refer to Inspection and Verification and the Symptom Chart for direction to the appropriate pinpoint test.

Pinpoint Test A: The Power Seat is Inoperative — Driver

Refer to Wiring Diagrams Cell 120 , Power Seats for schematic and connector information.

Normal Operation

The seat control switch is supplied battery voltage on circuit SBB32 (VT/RD) and ground on circuit GD133 (BK). The seat control switch then supplies voltage and ground to the appropriate circuits to operate the seat motors.

This pinpoint test is intended to diagnose the following:
• Fuse
• Wiring, terminals or connectors
• Seat control switch

PINPOINT TEST A: THE POWER SEAT IS INOPERATIVE — DRIVER

Pinpoint Test B: The Power Seat is Inoperative — Passenger

Refer to Wiring Diagrams Cell 120 , Power Seats for schematic and connector information.

Normal Operation

The seat control switch is supplied battery voltage on circuit SBB31 (WH/RD) and ground on circuit GD139 (BK/YE). The seat control switch then supplies voltage and ground to the appropriate circuits to operate the seat motors.

This pinpoint test is intended to diagnose the following:
• Fuse
• Wiring, terminals or connectors
• Seat control switch

PINPOINT TEST B: THE POWER SEAT IS INOPERATIVE — PASSENGER

Pinpoint Test C : The Power Seat Does Not Move Horizontally/Vertically — Driver

Refer to Wiring Diagrams Cell 120 , Seating for schematic and connector information.

Normal Operation

The seat control switch supplies battery voltage and ground to 1 of 3 power seat track motors through horizontal motor circuits CPS23 (GN/VT) and CPS28 (GN), front height motor circuits CPS24 (GY) and CPS25 (WH/VT) or rear height motor circuits CPS26 (YE/BU) and CPS27 (BU/BN) to move the seat in the desired direction.

This pinpoint test is intended to diagnose the following:
• Wiring, terminals or connectors
• Seat control switch
• Seat track motor

PINPOINT TEST C: THE POWER SEAT DOES NOT MOVE HORIZONTALLY/VERTICALLY — DRIVER

Pinpoint Test D: The Power Seat Does Move Horizontally/Vertically — Passenger

Refer to Wiring Diagrams Cell 120 , Seating for schematic and connector information.

Normal Operation

The seat control switch supplies battery voltage and ground to 1 of 3 power seat track motors through horizontal motor circuits CPS33 (WH) and CPS38 (GN/BU), front height motor circuits CPS34 (GY/BU) and CPS35 (VT/GN) or rear height motor circuits CPS36 (YE/GY) and CPS37 (WH/BU) to move the seat in the desired direction.

This pinpoint test is intended to diagnose the following:
• Wiring, terminals or connectors
• Seat control switch
• Seat track motor

PINPOINT TEST D: THE POWER SEAT DOES NOT MOVE HORIZONTALLY/VERTICALLY — PASSENGER

Pinpoint Test E: The Power Lumbar is Inoperative

Refer to Wiring Diagrams Cell 120 , Seating for schematic and connector information.

Normal Operation

The lumbar control switch is supplied battery voltage on circuit SBB32 (VT/RD) and ground on circuit GD133 (BK). When the lumbar control switch is pressed, voltage and ground are supplied to the power lumbar motor on circuits CPS65 (WH/GN) and CPS64 (BN/VT) to move the lumbar assembly in or out.

This pinpoint test is intended to diagnose the following:
• Wiring, terminals or connectors
• Lumbar control switch
• Power lumbar assembly

PINPOINT TEST E: THE POWER LUMBAR IS INOPERATIVE

Pinpoint Test F: The Heated Seats are Inoperative

Normal Operation

With the ignition ON, voltage is supplied from the Smart Junction Box (SJB) to each heated seat relay coil on circuit CBP43 (GY). Battery voltage is also supplied to the heated seat relay contacts (hot at all times) on circuit SBB16 (VT/RD). When the heated seat buttons are pressed, the Front Controls Interface Module (FCIM) illuminates the heated seat indicators and transmits a system request message to the HVAC module on the communication network. The HVAC module provides ground to heated seat relay coil circuits CHS30 (GN/YE) (driver) and CHS29 (WH/BU) (passenger) to operate the system. The engine must be running and both modules must be communicating correctly for the system to operate.

The HVAC module monitors the heated seat relay coil circuits for open, short to ground and short to voltage. If circuit faults are detected and DTCs are set for both seats, the HVAC module removes ground from the relay coils to disable the system (refer to HVAC Module DTC Chart in this section). The HVAC module also transmits network communication messages to the FCIM to deactivate the heated seat indicators. PIDs are available in the FCIM using a scan tool to check the heated seat switches and confirm correct module communication.

The heated seat system does not time-out and remains on until switched off or the engine is off.

This pinpoint test is intended to diagnose the following:
• Fuse(s)
• Wiring, terminals or connectors
• FCIM
• HVAC module

PINPOINT TEST F: THE HEATED SEATS ARE INOPERATIVE

Pinpoint Test G: The Heated Seat is Inoperative/Does Not Operate Correctly — Driver

Normal Operation

When the engine is running and the heated seat button is pressed, the Front Controls Interface Module (FCIM) illuminates the heated seat indicator and transmits a system request message to the HVAC module on the module communication network. The HVAC module receives the message and provides ground to the heated seat relay coil circuit CHS29 (WH/BU) to operate the heated seat. Voltage is supplied to the heated seat relay coil circuit CBP43 (GY) and relay contact circuit SBB16 (VT/RD). The relay energizes and supplies voltage to the cushion heater mat on circuit CHS02 (YE/BU). The cushion and backrest heater mats are connected in series by circuit CHS01 (GY/VT) and ground is supplied to the backrest heater mat circuit GD133 (BK), completing the circuit to heat the seat.

The heated seat switch can be checked using a scan tool to monitor the FCIM PID.

The HVAC module reports the following DTCs for the driver heated seat relay coil circuit CHS29 (WH/BU):

• DTC B1030:11 (Left Front Seat Heater Circuit Short To Ground) — If the driver heated seat relay coil circuit from the HVAC module is shorted to ground, the DTC is set and the seat will heat while the system is off.
• DTC B1030:12 (Left Front Seat Heater Circuit Short To Battery) — If the driver heated seat relay coil circuit from the HVAC module is shorted to voltage, the DTC is set and the seat will not heat.
• DTC B1030:13 (Left Front Seat Heater Circuit Open) — If the driver heated seat relay coil circuit from the HVAC module is open, the DTC is set and the seat will not heat.

This pinpoint test is intended to diagnose the following:
• Wiring, terminals or connectors
• Heated seat relay
• Cushion heater mat
• Backrest heater mat
• FCIM
• HVAC module

PINPOINT TEST G: THE HEATED SEAT IS INOPERATIVE/DOES NOT OPERATE CORRECTLY — DRIVER

Pinpoint Test H: The Heated Seat is Inoperative/Does Not Operate Correctly — Passenger

Normal Operation

When the engine is running and the heated seat button is pressed, the Front Controls Interface Module (FCIM) illuminates the heated seat indicator and transmits a system request message to the HVAC module on the module communication network. The HVAC module receives the message and provides ground to the heated seat relay coil circuit CHS30 (GY/YE) to operate the heated seat. Voltage is supplied to the heated seat relay coil circuit CBP43 (GY) and relay contact circuit SBB16 (VT/RD). The relay energizes and supplies voltage to the cushion heater mat on circuit CHS07 (GY/BU). The cushion and backrest heater mats are connected in series by circuit CHS06 (BU/BN) and ground is supplied to the backrest heater mat circuit GD139 (BK/YE), completing the circuit to heat the seat.

The heated seat switch can be checked using a scan tool to monitor the FCIM PID.

The HVAC module reports the following DTCs for the passenger heated seat relay coil circuit CHS30 (GY/YE):

• DTC B1032:11 (Right Front Seat Heater Circuit Short To Ground) — If the passenger heated seat relay coil circuit from the HVAC module is shorted to ground, the DTC is set and the seat will heat while the system is off.
• DTC B1032:12 (Right Front Seat Heater Circuit Short To Battery) — If the passenger heated seat relay coil circuit from the HVAC module is shorted to voltage, the DTC is set and the seat will not heat.
• DTC B1032:13 (Right Front Seat Heater Circuit Open) — If the passenger heated seat relay coil circuit from the HVAC module is open, the DTC is set and the seat will not heat.

This pinpoint test is intended to diagnose the following:
• Wiring, terminals or connectors
• Heated seat relay
• Cushion heater mat
• Backrest heater mat
• FCIM
• HVAC module

PINPOINT TEST H: THE HEATED SEAT IS INOPERATIVE/DOES NOT OPERATE CORRECTLY — PASSENGER

NOTICE: Do not install a new heater mat on a front passenger seat cushion. Install a new Occupant Classification System (OCS) service kit. Failure to follow this instruction can cause incorrect OCS system operation. Refer to Section 501-20B for the Occupant Classification Sensor Removal and Installation procedure.