Pinpoint Test B: The Heated Seat Is Inoperative/Does Not Operate Correctly - Driver
Seats
Pinpoint Tests
Pinpoint Test B: The Heated Seat is Inoperative/Does Not Operate Correctly - Driver
Refer to Wiring Diagram Set 119, Climate Controlled Seats for schematic and connector information. Diagrams By Number
Normal Operation
The heated seat relay is located inside the relay connector mounted to the seat track. When the ignition is ON, voltage is supplied from the Smart Junction Box (SJB) to the relay coil through relay enable circuit VHS35. With the engine running and heated seat switch on, ground is supplied to the opposite side of the relay coil from HVAC module heated seat relay drive circuit VHS18/CHS02 to energize the relay. The switch indicator can only be illuminated with the engine running. The relay contact closes to supply battery voltage from circuit CHS02 to the heater mat circuit CHS11. The heater mats are connected to ground circuit GD904 completing the electrical circuit to heat the seat.
- DTC B12AB (Drivers Heated Seat Relay Drive Circuit Shorted to Battery Voltage) - If the driver heated seat relay drive circuit VHS18/CHS02 is shorted to voltage and the HVAC module attempts to activate the driver heated seat relay, the DTC will set and the seat will fail to heat.
- 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.
This pinpoint test is intended to diagnose the following:
- Wiring, terminals or connectors
- Heated seat relay
- Backrest or cushion heater mat
- HVAC module
PINPOINT TEST B: THE HEATED SEAT IS INOPERATIVE/DOES NOT OPERATE CORRECTLY - DRIVER
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.
-------------------------------------------------
B1 CHECK THE HEATED SEAT AND INDICATOR OPERATION
- Start the engine.
- Operate the system, check the heated seat indicator for illumination and determine if the seat is heating.
- Does the heated seat indicator illuminate and does the seat heat?
Yes
Key OFF. GO to B11 to check the heater mats for an intermittent open circuit.
No
GO to B2.
-------------------------------------------------
B2 CHECK THE HVAC SYSTEM OPERATION AND HVAC MODULE FOR DTCs
- Verify the HVAC system operates.
- Enter the following diagnostic mode on the scan tool: Self Test - HVAC Module.
- Is DTC B12AB or B12AC retrieved?
Yes
If DTC B12AB is present, GO to B3.
If DTC B12AC is present, GO to B4.
For other DTCs or HVAC system concerns, REFER to Heating and Air Conditioning for diagnosis.
No
GO to B6.
-------------------------------------------------
B3 CHECK THE CONTROL CIRCUIT FOR A SHORT TO VOLTAGE
- Ignition OFF.
- Depower the Supplemental Restraint System (SRS). Refer to Supplemental Restraint System (SRS) Depowering and Repowering in the General Procedures portion of Restraint Systems.
- Disconnect: Driver Seat Side Air Bag C367.
- Disconnect: Driver Safety Belt Buckle and Pretensioner C3201.
- Disconnect: Driver Heated Seat Relay C3260.
- Disconnect: HVAC Module C2357A.
- 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.
- Ignition ON.
- Measure the voltage between driver heated seat relay C3260-2, circuit VHS18 (BN/GN), harness side and ground.
- Is any voltage present?
Yes
REPAIR the circuit. CLEAR the DTCs. REPEAT the self-test.
DISCONNECT the battery ground cable. CONNECT driver seat safety belt buckle and pretensioner C3201 and driver seat side air bag C367.
REPOWER the SRS. REFER to Restraint Systems.
No
INSTALL a new driver heated seat relay. RECONNECT all connectors and REPEAT the self-test. If the DTC is retrieved again, INSTALL a new HVAC module. CLEAR the DTCs. REPEAT the self-test.
DISCONNECT the battery ground cable. CONNECT driver seat safety belt buckle and pretensioner C3201 and driver seat side air bag C367.
REPOWER the SRS. REFER to Restraint Systems.
-------------------------------------------------
B4 CHECK THE CONTROL CIRCUIT 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: Driver Seat Side Air Bag C367.
- Disconnect: Driver Safety Belt Buckle and Pretensioner C3201.
- Disconnect: Driver Heated Seat Relay C3260.
- Disconnect: HVAC Module C2357A.
- Measure the resistance between driver heated seat relay C3260-2, circuit VHS18 (BN/GN), harness side and ground.
- Is the resistance greater than 10,000 ohms?
Yes
GO to B5.
No
REPAIR the circuit. CLEAR the DTCs. REPEAT the self-test.
CONNECT driver seat safety belt buckle and pretensioner C3201 and driver seat side air bag C367.
REPOWER the SRS. REFER to Restraint Systems.
-------------------------------------------------
B5 CHECK THE CONTROL CIRCUIT FOR AN OPEN
- Measure the resistance between driver heated seat relay C3260-2, circuit VHS18 (BN/GN), harness side and HVAC module C2357A-1, circuit CHS02 (YE/BU), harness side.
- Is the resistance less than 5 ohms?
Yes
CHECK the relay and HVAC module connectors and pins for damage. REPAIR as necessary. RECONNECT the connectors. REPEAT the self-test. If the DTC is retrieved again, INSTALL a new HVAC module. CLEAR the DTCs. REPEAT the self-test.
CONNECT driver seat safety belt buckle and pretensioner C3201 and driver seat side air bag C367.
REPOWER the SRS. REFER to Restraint Systems.
No
REPAIR the circuit. CLEAR the DTCs. REPEAT the self-test.
CONNECT driver seat safety belt buckle and pretensioner C3201 and driver seat side air bag C367.
REPOWER the SRS. REFER to Restraint Systems.
-------------------------------------------------
B6 CHECK THE HEATER CIRCUIT FOR VOLTAGE
- Ignition OFF.
- Depower the SRS. Refer to Supplemental Restraint System (SRS) Depowering and Repowering in the General Procedures portion of Restraint Systems.
- Disconnect: Driver Seat Side Air Bag C367.
- Disconnect: Driver Safety Belt Buckle and Pretensioner C3201.
- Disconnect: Driver Cushion Heater Mat C364.
- 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.
- Start the engine.
- Press the driver heated seat switch on and measure the voltage between driver seat cushion heater mat C364-1, circuit CHS11 (VT/GN), harness side and ground.
- Is the voltage greater than 10 volts?
Yes
GO to B10.
No
GO to B7.
-------------------------------------------------
B7 CHECK THE HEATER CIRCUIT FOR VOLTAGE WITH A NEW RELAY INSTALLED
- Ignition OFF.
- Disconnect: Driver Heated Seat Relay C3260.
- Install a new heated seat relay.
- Start the engine.
- Press the driver heated seat switch on and measure the voltage between driver seat heater mat C364-1, circuit CHS11 (VT/GN), harness side and ground.
- Is the voltage greater than 10 volts?
Yes
INSTALL a new heated seat relay. CLEAR the DTCs. REPEAT the self-test. TEST the system for normal operation.
DISCONNECT the battery ground cable. CONNECT driver seat safety belt buckle and pretensioner C3201 and driver seat side air bag C367.
REPOWER the SRS. REFER to Restraint Systems.
No
DISCONNECT the test relay and GO to B8.
-------------------------------------------------
B8 CHECK FOR VOLTAGE TO THE DRIVER HEATED SEAT RELAY
- Measure the voltage between:
- driver heated seat relay C3260-3, circuit CHS02 (YE/BU), harness side and ground.
- driver heated seat relay C3260-1, circuit VHS35 (VT/OG), harness side and ground.
- Are the voltages greater than 10 volts?
Yes
GO to B9.
No
VERIFY SJB fuses 18 (20A) and 43 (10A) are OK. If OK, REPAIR the circuit(s). If not OK, REFER to the Wiring Diagrams to identify the possible causes of the circuit short. CLEAR the DTCs. REPEAT the self-test. TEST the system for normal operation. Diagrams By Number
DISCONNECT the battery ground cable. CONNECT driver seat safety belt buckle and pretensioner C3201 and driver seat side air bag C367.
REPOWER the SRS. REFER to Restraint Systems.
-------------------------------------------------
B9 CHECK THE HEATER CIRCUIT FOR AN OPEN
- Ignition OFF.
- Measure the resistance between driver heated seat relay C3260-5, circuit CHS11 (VT/GN), harness side and driver cushion heater mat C364-1, circuit CHS11 (VT/GN), harness side.
- Is the resistance less than 5 ohms?
Yes
INSTALL a new HVAC module. CLEAR the DTCs. REPEAT the self-test. TEST the system for normal operation.
DISCONNECT the battery ground cable. CONNECT driver seat safety belt buckle and pretensioner C3201 and driver seat side air bag C367.
REPOWER the SRS. REFER to Restraint Systems.
No
REPAIR the circuit. CLEAR the DTCs. REPEAT the self-test. TEST the system for normal operation.
DISCONNECT the battery ground cable. CONNECT driver seat safety belt buckle and pretensioner C3201 and driver seat side air bag C367.
REPOWER the SRS. REFER to Restraint Systems.
-------------------------------------------------
B10 CHECK THE HEATER MAT GROUND CIRCUIT FOR AN OPEN
- Ignition OFF.
- Measure the resistance between driver cushion heater mat C364-2, circuit GD904 (BK/WH), harness side and ground.
- Is the resistance less than 5 ohms?
Yes
GO to B11.
No
REPAIR the circuit. CLEAR the DTCs. REPEAT the self-test. TEST the system for normal operation.
DISCONNECT the battery ground cable. CONNECT driver seat safety belt buckle and pretensioner C3201 and driver seat side air bag C367.
REPOWER the SRS. REFER to Restraint Systems.
-------------------------------------------------
B11 CHECK RESISTANCE OF THE CUSHION AND BACKREST HEATER MATS AND FOR AN INTERMITTENT OPEN
NOTE: Heater mat resistance tolerances are tight. Resistance can vary with temperature. Measurements should be carried out with the seat at room temperature.
- Disconnect: Driver Cushion Heater Mat C364.
- Carry out the following measurements with weight on the seat and check for an open heater mat.
- Measure the resistance between driver cushion heater C364 pins 1 and 2, component side (measures both cushion and backrest heater mats together in series).
- Disconnect: Driver Backrest Heater Mat Electrical Connector.
- Measure the resistance between driver backrest heater mat electrical connector pins 1 and 2, component side (measures backrest heater mat only).
- Is the resistance between 2.5 and 5 ohms at the cushion heater mat and between 1.0 and 2.5 ohms at the backrest heater mat with the seat occupied?
Yes
The system checks OK at this time. CHECK for loose or damaged connector pins and wiring damage. REPAIR as needed. CLEAR the DTCs. REPEAT the self-test. TEST the system for normal operation.
DISCONNECT the battery ground cable. CONNECT driver seat safety belt buckle and pretensioner C3201 and driver seat side air bag C367.
REPOWER the SRS. REFER to Restraint Systems.
No
If resistance of the backrest heater mat is OK, INSTALL a new cushion heater mat. REFER to Seat Cushion Heater Mat Seat Cushion Heater Mat. Otherwise, INSTALL a new backrest heater mat. REFER to Seat Backrest Heater Mat Seat Backrest Heater Mat. CLEAR the DTCs. REPEAT the self-test. TEST the system for normal operation.
DISCONNECT the battery ground cable. CONNECT driver seat safety belt buckle and pretensioner C3201 and driver seat side air bag C367.
REPOWER the SRS. REFER to Restraint Systems.
-------------------------------------------------