Pinpoint Test K: The Heated Seats are Inoperative
Seats
Pinpoint Tests
Pinpoint Test K: 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 HVAC module contains the heated seat control buttons and indicators. The heated seat system functions independently from the climate control system. A heated seat relay is located underneath each heated seat cushion frame. There are 2 voltage supplies to the heated seat relay. Voltage is supplied from the Smart Junction Box (SJB) heated seat relay enable circuit CBP42 (GN) on the driver seat and CBP42 (BU/RD) on the passenger seat to each heated seat relay coil when the ignition is ON. Ground is supplied to the opposite side of the driver or passenger relay coil by HVAC module driver heated seat relay drive circuit CHS29 (WH/BU) or passenger heated seat relay drive circuit CHS30 (GY/YE) when a heated seat switch button is pressed to energize the affected relay. This closes the relay contact to supply battery voltage from SJB circuit SBP18 (YE/RD) to the driver heater mat circuit CHS02 (YE/BU) or closes the relay contact to supply battery voltage from SJB circuit SBP18 (BU/RD) to the passenger heater mat circuit CHS07 (GY/BU). The driver and passenger heater mats are directly connected to ground circuit GD179 (BK/VT) completing the electrical circuit to heat the seats.
This pinpoint test is intended to diagnose the following:
- Fuse(s)
- Wiring, terminals or connectors
- HVAC module
- Heater mat
PINPOINT TEST K: THE HEATED SEATS ARE INOPERATIVE
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K1 CHECK THE HEATED SEAT INDICATORS
- Press both heated seat switches to ON.
- Do both heated seat switch indicators illuminate?
Yes
GO to K2.
No
Key OFF and DISASSEMBLE as necessary to disconnect all of the HVAC module electrical connectors. WAIT one minute to allow the system to reset and RECONNECT the electrical connectors. RETEST the system. If the heated seat indicator still does not illuminate, INSTALL a new HVAC module. TEST the system for normal operation.
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K2 CHECK THE HEATED SEAT RELAY FOR VOLTAGE
- Disconnect: Driver Heated Seat Relay C359.
- Measure the voltage between:
- driver heated seat relay C359-5 circuit SBP18 (YE/RD), harness side and ground.
- driver heated seat relay C359-2 circuit CBP42 (GN), harness side and ground.
- Are the voltages greater than 10 volts?
Yes
GO to K3.
No
VERIFY SJB fuses 18 (20A) and 42 (10A) are OK. If SJB fuse 18 (20A) is open, INSTALL a new fuse. If fuse blows immediately, REFER to the Wiring Diagrams to identify the possible causes of the circuit short. If fuse does not blow immediately, GO to K4. If OK, REPAIR the affected circuit SBP18 (YE/RD) or CBP42 (GN). TEST the system for normal operation. Diagrams By Number
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K3 CHECK THE GROUND CIRCUIT FOR AN OPEN
- Disconnect: Driver Seat Backrest Heater Mat C365.
- Measure the resistance between driver seat backrest heater mat C365-1 circuit GD179 (BK/VT), harness side and ground.
- Is the resistance less than 5 ohms?
Yes
INSTALL a new HVAC module. TEST the system for normal operation.
No
REPAIR the circuit. TEST the system for normal operation.
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K4 CHECK THE HEATER CIRCUITS FOR A SHORT TO GROUND
- Connect: Driver Heated Seat Relay C359.
- Activate both heated seats individually.
- START engine.
- PRESS the driver and passenger heated seat switch button.
- Did SJB fuse 18 (20A) open when activating either heated seat?
Yes
REPAIR circuit CHS07 (GY/BU) or CHS02 (YE/BU). TEST the system for normal operation.
No
INSTALL a new heated seat relay for the affected seat. TEST the system for normal operation.
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