Pinpoint Test R: The Heated Seat is Inoperative - Left Rear
Seats
Pinpoint Tests
Pinpoint Test R: The Heated Seat is Inoperative - Left Rear
Refer to Wiring Diagram Set 119, Climate Controlled Seats for schematic and connector information. Diagrams By Number
Normal Operation
When the LH or RH rear heated seat control switch is activated with the ignition ON, a ground signal is supplied to the heated seat module to command the system in high heat mode or low heat mode. When commanded ON, voltage is supplied to the heated seat switch from the heated seat module to illuminate the switch indicator. The heated seat module also supplies voltage to the LH or RH rear seat cushion and backrest heater mats, which are connected in series. Temperature is maintained by the heated seat module using a sensor contained within the cushion heater mat. The heated seat module supplies a reference voltage to the temperature sensor and monitors the return signal from the temperature sensor for controlling current flow to the heater mats. The heated seat module remains ON, heating the seat and maintaining temperature until switched OFF or the ignition voltage is switched OFF.
A new heated seat module must be configured after installation for correct operation. To configure, press the low heat mode button on either rear heated seat switch. Module configuration will occur automatically after the low heat mode button is pressed. Until the module is correctly configured, the heated seats will operate incorrectly when selecting the high heat mode by following a sequence of high, low and off with each button press. The system will operate correctly after the heated seat module receives a low heat request on either of the low heat request circuits and rear heated seat module configuration is activated.
This pinpoint test is intended to diagnose the following:
- Fuse
- Wiring, terminals or connectors
- Heater mat
- Heated seat switch
- Heated seat module
PINPOINT TEST R: THE HEATED SEAT IS INOPERATIVE - LEFT REAR
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R1 CHECK THE HEATED SEAT OPERATION
- Ignition ON.
- Operate the left rear heated seat switch.
- Does the seat operate in either setting?
Yes
If only the low setting operates, GO to R15.
If only the high setting operates, GO to R16.
No
GO to R2.
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R2 CHECK THE HEATED SEAT SWITCH INPUT
- Ignition OFF.
- For electrical connector access, release and lower the rear 60 percent seat backrest. Refer to the appropriate steps in Heated Seat Module - Rear Heated Seat Module - Rear.
- Disconnect: Rear Heated Seat Module C3162A.
- Measure the resistance between rear heated seat module C3162A-2, circuit CHS46 (YE/GN), harness side and ground while pressing the heated seat switch to high.
- Is the resistance less than 30 ohms when the switch is pressed and greater than 10,000 ohms when not pressed?
Yes
GO to R4.
No
GO to R3.
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R3 CHECK THE HEATED SEAT SWITCH GROUND CIRCUIT FOR AN OPEN
- Disconnect: Left Rear Heated Seat Switch C731.
- Measure the resistance between left rear heated seat switch C731-6, circuit GD139 (BK/YE), harness side and ground.
- Is the resistance less than 5 ohms?
Yes
GO to R17.
No
REPAIR the circuit. TEST the system for normal operation.
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R4 CHECK FOR VOLTAGE TO THE HEATED SEAT MODULE
- Disconnect: Rear Heated Seat Module C3162B.
- Measure the voltage between rear heated seat module C3162B-1, circuit SBB71 (WH/RD), harness side and ground.
- Is the voltage greater than 10 volts?
Yes
GO to R5.
No
VERIFY BCM fuse 71 (20A) is OK. If OK, REPAIR the circuit. TEST the system for normal operation. If not OK, REFER to the Wiring Diagrams to identify the possible causes of the circuit short. TEST the system for normal operation. Diagrams By Number
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R5 CHECK THE HEATER CIRCUITS AND HEATER MATS FOR AN OPEN
- Measure the resistance between rear heated seat module C3162B-4, circuit CHS39 (GN/BU), harness side and ground.
- Is the resistance between 2.5 and 4.5 ohms?
Yes
GO to R11.
No
GO to R6.
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R6 CHECK THE HEATER MAT GROUND CIRCUIT FOR AN OPEN
- Disconnect: Left Rear Backrest Heater Mat C3168.
- Measure the resistance between left rear backrest heater mat C3168-1, circuit GD134 (BK/VT), harness side and ground.
- Is the resistance less than 5 ohms?
Yes
GO to R7.
No
REPAIR the circuit. TEST the system for normal operation.
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R7 CHECK THE HEATER CIRCUIT FOR AN OPEN OR SHORT TO GROUND
- Disconnect: Left Rear Cushion Heater Mat C3167.
- Measure the resistance between:
- rear heated seat module C3162B-4, circuit CHS39 (GN/BU), harness side and left rear cushion heater mat C3167-1, circuit CHS39 (GN/BU), harness side.
- rear heated seat module C3162B-4, circuit CHS39 (GN/BU), harness side and ground.
- Is the resistance less than 5 ohms between C3162B-4 and C3167-1, and greater than 10,000 ohms between C3162B-4 and ground?
Yes
GO to R8.
No
REPAIR the circuit. TEST the system for normal operation.
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R8 CHECK THE CUSHION HEATER MAT FOR AN OPEN
- Measure the resistance between left rear heated seat cushion C3167 pins 1 and 4, component side.
- Is the resistance between 1.5 and 2.5 ohms?
Yes
GO to R9.
No
INSTALL a new cushion heater mat. REFER to Seat Cushion Heater Mat - Rear Seat Cushion Heater Mat - Rear. TEST the system for normal operation.
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R9 CHECK FOR AN OPEN OR A SHORT TO GROUND BETWEEN THE HEATER MATS
- Measure the resistance between:
- left rear cushion heater mat C3167-4, circuit CHS40 (GY/VT), harness side and left rear backrest heater mat C3168-2, circuit CHS40 (GY/VT), harness side.
- left rear cushion heater mat C3167-4, circuit CHS40 (GY/VT), harness side and ground.
- Is the resistance less than 5 ohms between C3167-4 and C3168-2, and greater than 10,000 ohms between C3167-4 and ground?
Yes
GO to R10.
No
REPAIR the circuit. TEST the system for normal operation.
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R10 CHECK THE BACKREST HEATER MAT FOR AN OPEN
- Measure the resistance between left rear backrest heater mat C3168 pins 1 and 2, component side.
- Is the resistance between 1 and 2 ohms?
Yes
The fault is intermittent. CHECK the electrical connectors for corrosion, poor pin contact or pushed out pins, particularly the pins and terminals of electrical connectors that were disconnected. Do not install any new components at this time. Components should only be installed when directed to do so in the pinpoint test. REPAIR any intermittent wiring, terminal or connector concerns found. TEST the system for normal operation.
No
INSTALL a new backrest heater mat. REFER to Seat Backrest Heater Mat - Rear Seat Backrest Heater Mat - Rear. TEST the system for normal operation.
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R11 CHECK THE TEMPERATURE SENSOR CIRCUIT FOR A SHORT TO VOLTAGE
- Ignition ON.
- Measure the voltage between rear heated seat module C3162A-3, circuit VHS42 (GN), harness side and ground.
- Is any voltage present?
Yes
REPAIR the circuit. GO to R14 to check the temperature sensor for damage. If temperature sensor is OK, TEST the system for normal operation.
No
GO to R12.
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R12 CHECK THE TEMPERATURE SENSOR CIRCUIT FOR A SHORT TO GROUND
- Ignition OFF.
- Measure the resistance between rear heated seat module C3162A-3, circuit VHS42 (GN), harness side and ground.
- Is the resistance greater than 10,000 ohms?
Yes
GO to R13.
No
REPAIR the circuit. TEST the system for normal operation.
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R13 CHECK THE TEMPERATURE SENSOR AND CIRCUITS FOR AN OPEN OR SHORT TO GROUND
- Connect: Left Rear Cushion Heater Mat C3167 (if previously disconnected).
- Measure the resistance between:
- rear heated seat module C3162A-3, circuit VHS42 (GN), harness side and C3162A-12, circuit RHS41 (GN/BN), harness side.
- rear heated seat module C3162A-3, circuit VHS42 (GN), harness side and ground.
- Is the resistance between 300 and 300K ohms between C3162A-3 and C3162A-12 and greater than 10,000 ohms between C3162A-3 and ground?
Yes
INSTALL a new heated seat module. REFER to Heated Seat Module - Rear Heated Seat Module - Rear. TEST the system for normal operation.
No
GO to R14.
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R14 CHECK THE TEMPERATURE SENSOR FOR AN OPEN
- Disconnect: Left Rear Cushion Heater Mat C3167.
- Measure the resistance between left rear cushion heater mat C3167 pins 2 and 3, component side.
- Is the resistance between 8,000 and 15,000 ohms?
Yes
REPAIR circuit RHS41 (GN/BN) or VHS42 (GN). TEST the system for normal operation.
No
INSTALL a new cushion heater mat. REFER to Seat Cushion Heater Mat - Rear Seat Cushion Heater Mat - Rear. TEST the system for normal operation.
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R15 CHECK THE HIGH HEAT REQUEST CIRCUIT FOR AN OPEN OR SHORT TO GROUND
- For electrical connector access, release and lower the rear 60 percent seat backrest. Refer to the appropriate steps in Heated Seat Module - Rear Heated Seat Module - Rear.
- Disconnect: Left Rear Heated Seat Switch C731.
- Measure the resistance between:
- rear heated seat module C3162A-2, circuit CHS46 (YE/GN), harness side and left rear heated seat switch C731-1, circuit CHS46 (YE/GN), harness side.
- rear heated seat module C3162A-2, circuit CHS46 (YE/GN), harness side and ground.
- Is the resistance less than 5 ohms between C3162A-2 and C731-1 and greater than 10,000 ohms between C3162A-2 and ground?
Yes
GO to R17.
No
REPAIR the circuit. TEST the system for normal operation.
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R16 CHECK THE LOW HEAT REQUEST CIRCUIT FOR AN OPEN OR SHORT TO GROUND
- Disconnect: Left Rear Heated Seat Switch C731.
- For electrical connector access, release and lower the rear 60 percent seat backrest. Refer to the appropriate steps in Heated Seat Module - Rear Heated Seat Module - Rear.
- Measure the resistance between:
- rear heated seat module C3162A-1, circuit CHS47 (VT/GN), harness side and left rear heated seat switch C731-5, circuit CHS47 (VT/GN), harness side.
- rear heated seat module C3162A-1, circuit CHS47 (VT/GN), harness side and ground.
- Is the resistance less than 5 ohms between C3162A-1 and C731-5 and greater than 10,000 ohms between C3162A-1 and ground?
Yes
GO to R17.
No
REPAIR the circuit. TEST the system for normal operation.
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R17 CHECK THE HEATED SEAT SWITCH
- Disconnect: Left Rear Heated Seat Switch C731.
- Use the following chart and measure the resistance between rear heated seat switch pins, component side, while pressing the indicated switch buttons and compare the results.
- Is the heated seat switch OK?
Yes
INSTALL a new heated seat module. REFER to Heated Seat Module - Rear Heated Seat Module - Rear. TEST the system for normal operation.
No
INSTALL a new heated seat switch. REFER to Heated Seat Switch - Rear Heated Seat Switch - Rear.
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