Pinpoint Test D: The Heated Seat Does Not Operate Correctly - Driver or Passenger Seat Heats When the System is Off
Seats
Pinpoint Tests
Pinpoint Test D: The Heated Seat Does Not Operate Correctly - Driver or Passenger Seat Heats When the System is Off
Refer to Wiring Diagram Set 119, Climate Controlled Seats for schematic and connector information. Diagrams By Number
Normal Operation
With the engine running and a heated seat button is pressed ON, the HVAC module supplies a switched ground output to driver heated seat relay circuit VHS18 or passenger heated seat relay circuit CHS30 to energize the relay coil. When energized, the driver or passenger heated seat relay contact closes and supplies voltage to driver seat heater circuit CHS11 or passenger seat heater circuit CHS07 to heat the seat.
The HVAC module monitors the output circuits VHS18/CHS02 (driver) and CHS30/CHS07 (passenger) for faults. If circuit VHS18/CHS02 (driver) or CHS30/CHS07 (passenger) is shorted to ground, HVAC DTC B12AC (driver seat) or B12AE (passenger seat) will set. If a short to ground condition exists on the output circuit, the seat will continue to heat after being switched off. If DTC B12AC or B12AE is set and the seat is inoperative, GO to Pinpoint Test B (driver seat) or GO to Pinpoint Test C (passenger seat) to diagnose the fault. Pinpoint Test B: The Heated Seat is Inoperative/Does Not Operate Correctly - Driver Pinpoint Test C: The Heated Seat is Inoperative/Does Not Operate Correctly - Passenger
- DTC B12AC (Drivers Heated Seat Relay Drive Circuit Open or Shorted to Ground) - If the driver heated seat relay drive circuit VHS18/CHS02 is open or shorted to ground and the HVAC module attempts to activate the driver heated seat relay, the DTC will set and the seat will fail to heat (circuit open) or may be on at all times (circuit shorted to ground) until the ignition key is OFF.
- DTC B12AE (Passenger Heated Seat Relay Drive Circuit Open or Shorted to Ground) - If the passenger heated seat relay drive circuit CHS30/CHS07 is open or shorted to ground and the HVAC module attempts to activate the passenger heated seat relay, the DTC will set and the seat will fail to heat (circuit open) or may be on at all times (circuit shorted to ground) until the ignition key is OFF.
This pinpoint test is intended to diagnose the following:
- Wiring, terminals or connectors
- Heated seat relay
- HVAC module
PINPOINT TEST D: THE HEATED SEAT DOES NOT OPERATE CORRECTLY - DRIVER OR PASSENGER SEAT HEATS WHEN THE SYSTEM IS OFF
NOTE: Several heated seat circuits change circuit numbers and wire colors at the seat-to-body electrical connectors. Be sure circuits are tested as described in this procedure for correct diagnosis.
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D1 CHECK THE HVAC MODULE FOR HEATED SEAT DTCs
- Enter the following diagnostic mode on the scan tool: Self Test - HVAC Module.
- Are any DTCs retrieved?
Yes
For DTC B12AC or B12AE, GO to D2. For others, REFER to the HVAC DTC Chart. [1][2]Diagnostic Trouble Code Descriptions
No
GO to D3.
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D2 CHECK THE HEATED SEAT RELAY DRIVE CIRCUIT FOR A SHORT TO GROUND
- Ignition OFF.
- Depower the Supplemental Restraint System (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: Driver Seat Side Air Bag C367 or Passenger Seat Side Air Bag C337.
- Disconnect: Driver Safety Belt Buckle and Pretensioner C3201 or Passenger Safety Belt Buckle and Pretensioner C3202.
- Disconnect: Driver Heated Seat Relay C3260 or Passenger Heated Seat Relay C3261.
- Disconnect: HVAC Module C2357A.
- For driver seat, measure the resistance between driver heated seat relay C3260-2, circuit VHS18 (BN/GN), harness side and ground.
- For passenger seat, measure the resistance between passenger heated seat relay C3261-1, circuit CHS30 (GY/YE), harness side and ground.
- Is the resistance greater than 10,000 ohms?
Yes
INSTALL a new driver or passenger heated seat relay.
RECONNECT the connectors. REPEAT the self-test. If the DTC is retrieved again, INSTALL a new HVAC module. REFER to Climate Control Heating Ventilation Air Conditioning (HVAC) Module. CLEAR the DTCs. REPEAT the self-test.
CONNECT driver seat safety belt buckle and pretensioner C3201 or passenger seat safety belt buckle and pretensioner C3202. CONNECT driver seat side air bag C367 or passenger seat side air bag C337.
REPOWER the SRS. REFER to Supplemental Restraint System Supplemental Restraint System (SRS) Depowering and Repowering.
No
REPAIR the circuit. CLEAR the DTCs. REPEAT the self-test.
CONNECT driver seat safety belt buckle and pretensioner C3201 or passenger seat safety belt buckle and pretensioner C3202 and driver seat side air bag C367 or passenger seat side air bag C337.
REPOWER the SRS. REFER to Supplemental Restraint System Supplemental Restraint System (SRS) Depowering and Repowering.
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D3 CHECK THE HEATER CIRCUIT FOR A SHORT TO VOLTAGE
- 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: Driver Seat Side Air Bag C367 or Passenger Seat Side Air Bag C337.
- Disconnect: Driver Safety Belt Buckle and Pretensioner C3201 or Passenger Safety Belt Buckle and Pretensioner C3202.
- Disconnect: Driver Heated Seat Relay C3260 or Passenger Heated Seat Relay C3261.
- Disconnect: Driver Cushion Heater Mat C364 or Passenger Cushion Heater Mat C334.
- WARNING: Make sure no one is in the vehicle and there is nothing blocking or placed in front of any air bag module when the battery is connected. Failure to follow these instructions may result in serious personal injury in the event of an accidental deployment.
- Connect the battery ground cable. Refer to Battery, Mounting and Cables Battery Disconnect.
- Ignition ON.
- For driver seat, measure the voltage between driver seat cushion heater mat C364-1, circuit CHS11 (VT/GN), harness side and ground.
- For passenger seat, measure the voltage between passenger seat cushion heater mat C334-1, circuit CHS07 (GY/BU), harness side and ground.
- Is any voltage present?
Yes
REPAIR the circuit. CLEAR the DTCs. REPEAT the self-test. TEST the system for normal operation.
CONNECT driver seat safety belt buckle and pretensioner C3201 or passenger seat safety belt buckle and pretensioner C3202. CONNECT driver seat side air bag C367 or passenger seat side air bag C337.
REPOWER the SRS. REFER to Supplemental Restraint System Supplemental Restraint System (SRS) Depowering and Repowering.
No
INSTALL a new driver or passenger heated seat relay. CLEAR the DTCs. REPEAT the self-test. TEST the system for normal operation.
CONNECT driver seat safety belt buckle and pretensioner C3201 or passenger seat safety belt buckle and pretensioner C3202. CONNECT driver seat side air bag C367 or passenger seat side air bag C337.
REPOWER the SRS. REFER to Supplemental Restraint System Supplemental Restraint System (SRS) Depowering and Repowering.
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