Pinpoint Test M: The Heated Seats Are Inoperative
Seats
Pinpoint Tests
Pinpoint Test M: The Heated Seats are Inoperative
Refer to Wiring Diagram Set 119, Climate Controlled Seats for schematic and connector information. Diagrams By Number
Normal Operation
The driver and passenger heated seats share a common ignition and battery feed to the heated seat control switch assembly. Ignition feed circuit CBP18 (GY/OG) supplies voltage to the logic board and illumination of the heated seat switch assembly and the battery feed circuit SBB28 (GN/RD) is used to provide voltage to the heater mats. The heated seat switch assembly uses shared ground GD145 (BK/BU) for the logic board and illumination.
When a heated seat switch is pressed with the ignition switch in RUN or START, a momentary ground is provided to the logic board of the heated seat switch assembly. The logic board then activates an internal relay in the heated seat switch assembly that provides voltage via circuit CHS02 (YE/BU) (driver seat) or CHS07 (GY/BU) (front passenger seat) to the bi-metallic thermostat that is part of the seat cushion heater mat.
The driver seat cushion and backrest heater mats are wired in series as are the passenger seat cushion and backrest heater mats. The heated seat system is designed to maintain the temperature by the opening (no voltage to the heated seat elements) and closing (voltage supplied to the heated seat elements) of the bi-metallic thermostat.
This pinpoint test is intended to diagnose the following:
- Fuse(s)
- Wiring, terminals or connectors
- Heated seat switch
- Heated seat relay
- Heated seat mat
PINPOINT TEST M: THE HEATED SEATS ARE INOPERATIVE
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M1 CHECK HEATED SEAT SWITCH OPERATION
- Ignition ON.
- Press both heated seat switches to ON.
- Does one or both heated seat switch indicators illuminate?
Yes
If one or both indicators illuminate, GO to Pinpoint Test N. Pinpoint Test N: The Heated Seat Is Inoperative - Driver Or Passenger
No
GO to M2.
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M2 CHECK VOLTAGE TO HEATED SEAT SWITCH CIRCUITS
- Ignition OFF.
- Disconnect: Heated Seat Switch C2347.
- Ignition ON.
- Measure the voltage between the following heated seat switch C2347 pins, harness side and ground.
- Are the voltages greater than 10 volts?
Yes
GO to M3.
No
VERIFY Battery Junction Box (BJB) fuse 28 (20A) and Smart Junction Box (SJB) fuse 18 (10A) are OK. If OK, REPAIR circuit CBP18 (GY/OG) or SBB28
(GN/RD). If not OK, REFER to the Wiring Diagrams to identify possible causes of the circuit short. TEST the system for normal operation. Diagrams By Number
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M3 CHECK HEATED SEAT SWITCH GROUND CIRCUIT
- Ignition OFF.
- Measure the resistance between heated seat switch C2347-10, circuit GD145 (BK/BU), harness side and ground.
- Is the resistance less than 5 ohms?
Yes
INSTALL a new heated seat switch. REFER to Heated Seat Switch Heated Seat Switch.
No
REPAIR circuit GD145 (BK/BU). TEST the system for normal operation.
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