Pinpoint Test O: The Heated Seat Is Inoperative - Left Rear
Seats
Pinpoint Tests
Pinpoint Test O: 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
The Smart Junction Box (SJB) supplies battery voltage to the rear heated seat module on circuit SBP18 (YE/RD), ignition voltage is supplied from the SJB on circuit CPB35 (YE/GY) and ground on circuit GD145 (BK/BU). When the heated seat control switch is pressed, a ground signal is sent to the heated seat module to command the system ON or OFF in HIGH heat mode or LOW heat mode. When commanded ON, a ground signal is supplied from the heated seat switch to the heated seat module on either circuit CHS48 (YE) (HIGH heat mode) or circuit CHS49 (VT) (LOW heat mode) illuminating the switch indicator. The heated seat module also supplies voltage to the cushion and backrest heater mats on circuit CHS39 (GN/BU) and ground to the heater mats on circuit GD145 (BK/BU). The cushion and backrest heater mats are connected in series and operate together. 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 on circuit VHS42 (GN) and monitors the return signal from the temperature sensor on circuit RHS41 (GN/BN) for adjusting the current flow to the heater mats. The heated seat module is designed to remain ON, heating the seat and maintaining temperature until switched OFF.
This pinpoint test is intended to diagnose the following:
- Fuse
- Wiring, terminals or connectors
- Heater mat
- Rear heated seat switch
- Rear heated seat module
PINPOINT TEST O: THE HEATED SEAT IS INOPERATIVE - LEFT REAR
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O1 CHECK DRIVER REAR HEATED SEAT OPERATION
- Ignition ON.
- Operate the left rear heated seat in the HIGH and LOW setting.
- Does the seat operate in either setting?
Yes
If only the LOW setting operates, GO to O15.
If only the HIGH setting operates, GO to O16.
No
GO to O2.
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O2 CHECK DRIVER REAR HEATED SEAT SWITCH INPUT
- Disconnect: Rear Heated Seat Module C3304a.
- Measure the resistance between rear heated seat module C3304a-2, circuit CHS46 (YE/GN), harness side and ground while pressing the high heated seat switch.
- Is the resistance less than 30 ohms when the heated seat switch is pressed and greater than 10,000 ohms when the heated seat switch is not pressed?
Yes
GO to O4.
No
GO to O3.
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O3 CHECK DRIVER REAR HEATED SEAT SWITCH GROUND CIRCUIT FOR AN OPEN
- Disconnect: Rear Driver Heated Seat Switch C320.
- Measure the resistance between rear driver heated seat switch C320-1, circuit GD114 (BK/BU), harness side and ground.
- Is the resistance less than 5 ohms?
Yes
GO to O17.
No
REPAIR the circuit. TEST the system for normal operation.
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O4 CHECK THE VOLTAGE TO THE DRIVER HEATED SEAT MODULE FEED CIRCUIT
- Disconnect: Rear Heated Seat Module C3304b.
- Measure the voltage between rear heated seat module C3304b-1, circuit SBP18 (YE/RD), harness side and ground.
- Is the voltage greater than 10 volts?
Yes
GO to O5.
No
VERIFY Smart Junction Box (SJB) fuse 18 (20A) is OK. If OK, REPAIR the affected circuit. TEST the system for normal operation. If not OK, REFER to the Wiring Diagrams to identify the possible causes of the circuit short. Diagrams By Number
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O5 CHECK THE DRIVER HEATER MATS RESISTANCE AND HEATER CIRCUITS FOR AN OPEN
- Measure the resistance between rear heated seat module C3304b-4, circuit CHS39 (GN/BU), harness side and ground.
- Is the resistance between 1.2 and 4 ohms?
Yes
GO to O11.
No
GO to O6.
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O6 CHECK DRIVER HEATER MATS GROUND CIRCUIT FOR AN OPEN
- Disconnect: Backrest Heater Mat C3168.
- Measure the resistance between driver backrest heater mat C3168-1, circuit GD145 (BK/BU), harness side and ground.
- Is the resistance less than 5 ohms?
Yes
GO to O7.
No
REPAIR the circuit. TEST the system for normal operation.
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O7 CHECK DRIVER REAR HEATER CIRCUIT CHS39 (GN/BU) FOR AN OPEN AND A SHORT TO GROUND
- Disconnect: Rear Seat Cushion C3045.
- Measure the resistance between:
- rear heated seat module C3304b-4, circuit CHS39 (GN/BU), harness side and rear seat cushion heater mat C3045-1, circuit CHS39 (GN/BU), harness side.
- rear heated seat module C3304b-4, circuit CHS39 (GN/BU), harness side and ground.
- Is the resistance less than 5 ohms between C3304b-4 and C3045-1, and greater than 10,000 ohms between C3304b-4 and ground?
Yes
GO to O8.
No
REPAIR the circuit. TEST the system for normal operation.
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O8 CHECK DRIVER CUSHION HEATER MAT FOR AN OPEN
- Measure the resistance between rear heated seat cushion C3045 pin 1 and pin 2, component side.
- Is the resistance between 0.6 and 2 ohms?
Yes
GO to O9.
No
INSTALL a new rear seat 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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O9 CHECK DRIVER REAR HEATER CIRCUIT CHS11 (VT/GN) FOR AN OPEN
- Measure the resistance between rear seat cushion heater mat C3045-2, circuit CHS11 (VT/GN), harness side and rear seat backrest heater mat C3168-2, circuit CHS11 (VT/GN), harness side.
- Is the resistance less than 5 ohms?
Yes
GO to O10.
No
REPAIR the circuit. TEST the system for normal operation.
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O10 CHECK DRIVER BACKREST HEATER MAT FOR AN OPEN
- Measure the resistance between left rear backrest heater C3168 pins 1 and 2, component side.
- Is the resistance between 0.6 and 2 ohms?
Yes
GO to O11.
No
INSTALL a new rear seat 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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O11 CHECK TEMPERATURE SENSOR CIRCUIT VHS42 (GN) FOR A SHORT TO VOLTAGE
- Ignition ON.
- Measure the voltage between rear heated seat module C3304a-3, circuit VHS42 (GN), harness side and ground.
- Is any voltage present?
Yes
REPAIR the circuit. TEST the system for normal operation.
No
GO to O12.
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O12 CHECK THE HEATED SEAT TEMPERATURE SENSOR CIRCUITS FOR AN OPEN AND SHORT TO GROUND
- Ignition OFF.
- Connect: Rear Seat Cushion C3045.
- Measure the resistance between:
- rear heated seat module C3304a-3, circuit VHS42 (GN), harness side and C3304a-12, circuit RHS41 (BK/BU), harness side.
- rear heated seat module C3304a-3, circuit VHS42 (GN), harness side and ground.
- Is the resistance greater than 300 and less than 300,000 ohms between C3304a-3 and C3304a-12 and greater than 10,000 ohms between C3304a-12 and ground?
Yes
INSTALL a new rear heated seat module. REFER to Heated Seat Module - Rear Heated Seat Module - Rear. TEST the system for normal operation.
No
GO to O13.
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O13 CHECK THE HEATED SEAT TEMPERATURE SENSOR CIRCUIT VHS42 (GN) FOR AN OPEN AND SHORT TO GROUND
- Disconnect: Rear Seat Cushion C3045.
- Measure the resistance between:
- rear heated seat module C3304a-3, circuit VHS42 (GN), harness side and rear seat cushion heater mat C3045-3, circuit VHS42 (GN), harness side.
- rear heated seat module C3304a-3, circuit VHS42 (GN), harness side and ground.
- Is the resistance less than 5 ohms between C3304a-3 and C3045-3, and greater than 10,000 ohms between C3304a-3 and ground?
Yes
GO to O14.
No
REPAIR the circuit. TEST the system for normal operation.
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O14 CHECK THE TEMPERATURE SENSOR FOR AN OPEN
- Measure the resistance between rear heated seat cushion C3045 pin 3 and pin 4, component side.
- Is the resistance between 300 ohms and 300,000 ohms?
Yes
REPAIR ground circuit RHS41 (GN/BN). TEST the system for normal operation.
No
INSTALL a new rear seat 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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O15 CHECK HEATED SEAT SWITCH HIGH CIRCUIT FOR AN OPEN AND A SHORT TO GROUND
- Disconnect: Rear Heated Seat Module C3304a.
- Disconnect: Heated Seat Switch C320.
- Measure the resistance between:
- rear heated seat module C3304a-2, circuit CHS46 (YE/GN), harness side and left rear heated seat switch C320-2, circuit CHS46 (YE/GN), harness side.
- rear heated seat module C3304a-2, circuit CHS46 (YE/GN), harness side and ground.
- Is the resistance less than 5 ohms between the heated seat module and the heated seat switch and greater than 10,000 ohms between the heated seat module and ground?
Yes
GO to O17.
No
REPAIR the circuit. TEST the system for normal operation.
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O16 CHECK HEATED SEAT SWITCH LOW CIRCUIT FOR AN OPEN AND A SHORT TO GROUND
- Disconnect: Heated Seat Switch C320.
- Measure the resistance between:
- rear heated seat module C3304a-1, circuit CHS47 (VT/GN), harness side and left rear heated seat switch C320-6, circuit CHS47 (VT/GN), harness side.
- rear heated seat module C3304a-1, circuit CHS47 (YE/GN), harness side and ground.
- Is the resistance less than 5 ohms between the heated seat module and the heated seat switch and greater than 10,000 ohms between the heated seat module and ground?
Yes
GO to O17.
No
REPAIR the circuit. TEST the system for normal operation.
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O17 CHECK THE REAR HEATED SEAT SWITCH
- Disconnect: Heated Seat Switch C320.
- Measure the resistance between rear heated seat switch pins, component side, while pressing the indicated switch buttons and compare the results to the table.
- Is the resistance less than 30 ohms with the switch buttons depressed and greater than 10,000 ohms with the switch buttons released?
Yes
INSTALL a new left rear heated seat module. REFER to Heated Seat Module - Rear Heated Seat Module - Rear. TEST the system for normal operation.
No
INSTALL a new rear heated seat switch. REFER to Heated Seat Switch - Rear Heated Seat Switch - Rear.
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