Pinpoint Test N: The Heated Seats are Inoperative - Rear
Seats
Pinpoint Test N: The Heated Seats are Inoperative - Rear
Normal Operation
The heated seat module receives battery voltage on circuit SBP18 (YE/RD) and ignition voltage on circuit CBP35 (YE/GY), and is supplied ground on circuit GD145 (BK/BU). When the left rear heated seat control switch is pressed with the ignition in RUN or START, a ground is supplied on circuit CHS46 (YE/GN) to command the system on or off in high heat mode or circuit CHS47 (VT/GN) to command the system on or off in low heat mode. When the right rear heated seat control switch is pressed with the ignition in RUN or START, a ground is supplied on circuit CHS50 (BU/GY) to command the system on or off in high heat mode or circuit CHS51 (YE/GY) to command the system on or off in low heat mode. When commanded on, voltage is supplied to the heated seat switch from the heated seat module on either circuit CHS48 (YE) (left rear) or CHS52 (BU) (right rear) (high heat mode); or circuit CHS49 (VT) (left rear) or CHS53 (WH/BN) (right rear) (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) (left rear) or CHS43 (GY/BU) (right rear) 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 monitors the temperature sensors on circuit VHS42 (GN) (left rear) or VHS45 (GY/BN) (right rear) for adjusting the current flow to the heater mats and uses a ground supplied on circuit RHS41 (GN/BN). The heated seat module is designed to remain 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(s)
- Wiring, terminals or connectors
- Heated seat module
PINPOINT TEST N : THE HEATED SEATS ARE INOPERATIVE - REAR
N1 CHECK THE VOLTAGE TO THE REAR HEATED SEAT MODULE
- Disconnect: Heated Seat Module C3304b.
- Ignition ON.
- Measure the voltage between:
- heated seat module C3304B-2, circuit CBP35 (YE/GY), harness side and ground.
- heated seat module C3304B-1, circuit SBP18 (YE/RD), harness side and ground.
Are the voltages greater than 10 volts?
Yes
GO to N2.
No
VERIFY Smart Junction Box (SJB) fuses 18 (20A) and 35 (10A) are 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. Electrical Diagrams
N2 CHECK THE REAR HEATED SEAT MODULE GROUND CIRCUITS FOR AN OPEN
- Ignition OFF.
- Disconnect: Backrest Heater Mat C3168.
- Measure the resistance between left rear seat backrest heater mat C3168-1, circuit GD145 (BK/BU), harness side and ground.
- Measure the resistance between heated seat module C3304B-5, circuit GD145 (BK/BU), harness side and ground.
Are the resistances less than 5 ohms?
Yes
GO to N3.
No
REPAIR the affected circuit. TEST the system for normal operation.
N3 CHECK TEMPERATURE SENSOR CIRCUITS FOR A SHORT TO VOLTAGE
- Disconnect: Heated Seat Module C3304a.
- Ignition ON.
- Measure the voltage between:
- heated seat module C3304A-3, circuit VHS42 (GN), harness side and ground.
- heated seat module C3304A-9, circuit VHS45 (GY/BN), harness side and ground.
Is voltage present on either circuit?
Yes
REPAIR the affected circuit. TEST the system for normal operation.
No
GO to N4.
N4 CHECK TEMPERATURE SENSOR CIRCUITS FOR A SHORT TO GROUND
- Ignition OFF.
- Measure the resistance between:
- heated seat module C3304A-3, circuit VHS42 (GN), harness side and ground.
- heated seat module C3304A-9, circuit VHS45 (GY/BN), harness side and ground.
Are the resistances greater than 10,000 ohms?
Yes
GO to N5.
No
REPAIR the affected circuit. TEST the system for normal operation.
N5 CHECK THE TEMPERATURE SENSOR RETURN CIRCUIT FOR AN OPEN
- Measure the resistance between heated seat module C3304A-12, circuit RHS41 (GN/BN), harness side and left rear heated seat C3304A-3, circuit VHS42 (GN), harness side.
Is the resistance between 300 and 300,000 ohms?
Yes
INSTALL a new heated seat module. REFER to Heated Seat Module - Rear . TEST the system for normal operation.
No
REPAIR circuit RHS41 (GN/BN). TEST the system for normal operation.