Pinpoint Test O: The Heated Seat is Inoperative - Left Rear
Seats
Pinpoint Test O: The Heated Seat is Inoperative - Left Rear
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 (Smart Junction Box) 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
O1 CHECK 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 O14.
If only the high setting operates, GO to O15.
No
GO to O2.
O2 CHECK HEATED SEAT SWITCH INPUT
- Ignition OFF.
- 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 released?
Yes
GO to O4.
No
GO to O3.
O3 CHECK HEATED SEAT SWITCH GROUND CIRCUIT FOR AN OPEN
- Disconnect: Rear Heated Seat Switch C320.
- Measure the resistance between right rear 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.
O4 CHECK THE VOLTAGE TO THE REAR HEATED SEAT MODULE
- 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
REPAIR the circuit. TEST the system for normal operation.
O5 CHECK THE PASSENGER HEATER MATS RESISTANCE AND HEATER MAT 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 O10.
No
GO to O6.
O6 CHECK HEATER 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.
O7 CHECK REAR SEAT CUSHION CIRCUIT 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 the rear heated seat module and the rear heated seat cushion and greater than 10,000 ohms between the rear heated seat module and ground?
Yes
GO to O8.
No
REPAIR the circuit. TEST the system for normal operation.
O8 CHECK THE PASSENGER 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 . TEST the system for normal operation.
O9 CHECK THE DRIVER SEAT BACKREST HEATER MAT FOR AN OPEN
- Measure the resistance between right rear seat backrest heater C3168 pins 1 and 2, component side.
Is the resistance between 0.6 and 2 ohms?
Yes
REPAIR circuit CHS11 (VT/GN) for an open. TEST the system for normal operation.
No
INSTALL a new rear seat backrest heater mat. REFER to Seat Backrest Heater Mat - Rear . TEST the system for normal operation.
O10 CHECK THE TEMPERATURE SENSOR CIRCUIT FOR A SHORT TO VOLTAGE
- Ignition ON.
- Measure the voltage between 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 O11.
O11 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:
- heated seat module C3304A-3, circuit VHS42 (GN), harness side and C3304A-12, circuit RHS41 (GN/BN), harness side.
- 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 between the heated seat module pins and greater than 10,000 ohms between the heated seat module and ground?
Yes
GO to O18
No
GO to O12.
O12 CHECK THE HEATED SEAT TEMPERATURE SENSOR CIRCUIT FOR AN OPEN AND A 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 the heated seat module and the rear seat cushion heater mat and greater than 10,000 ohms between the heated seat module and ground?
Yes
GO to O13.
No
REPAIR the circuit. TEST the system for normal operation.
O13 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 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 . TEST the system for normal operation.
O14 CHECK THE HEATED SEAT SWITCH HIGH CIRCUIT FOR AN OPEN AND A SHORT TO GROUND
- Ignition OFF.
- 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 right 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 O16.
No
REPAIR the circuit. TEST the system for normal operation.
O15 CHECK THE HEATED SEAT SWITCH LOW CIRCUIT FOR AN OPEN AND A SHORT TO GROUND
- Ignition OFF.
- Disconnect: Rear Heated Seat Module C3304A.
- 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 (VT/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 O16.
No
REPAIR the circuit. TEST the system for normal operation.
O16 CHECK THE REAR HEATED SEAT SWITCH
- Measure the resistance between rear heated seat switch pins, component side, while pressing the indicated switch buttons and compare the results to the table.
Heated Seat Switch Pins Ohms High Heated Seat Switch 2 and 1 Less than 30 when pressed; greater than 10,000 when released. Low Heated Seat Switch 6 and 1 Less than 30 when pressed; greater than 10,000 when released.
Is the resistance less than 30 ohms with the switch buttons depressed and greater than 10,000 ohms with the switch buttons released?
Yes
GO to O18.
No
INSTALL a new rear heated seat switch. REFER to Heated Seat Switch - Rear .
O17 CHECK HEATED SEAT SWITCH CIRCUIT FOR AN OPEN
NOTE: This step tests for an open circuit in the wiring harness interconnectors.
- 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.
Is the resistance less than 5 ohms?
Yes
INSTALL a new rear heated seat switch. REFER to Heated Seat Switch - Rear .
No
REPAIR the circuit. TEST the system for normal operation.
O18 CHECK FOR CORRECT REAR HEATED SEAT MODULE OPERATION
- Disconnect: Rear Heated Seat Module Connectors.
- Check for:
- corrosion
- pushed-out pins
- spread terminals
- Connect: Rear Heated Seat Module Connectors.
- Connect the rear heated seat module connectors and make sure they seat correctly.
- Operate the system and verify the concern is still present.
Is the concern still present?
Yes
INSTALL a new rear heated seat module module. REFER to Heated Seat Module - Rear . TEST the system for normal operation.
No
The system is operating correctly at this time. The concern may have been caused by a loose or corroded connector. CLEAR the DTCs. REPEAT the self-test.