Pinpoint Test U: The Heated Seat is Inoperative/Does Not Operate Correctly - Left Rear
Seats
Pinpoint Test U: The Heated Seat is Inoperative/Does Not Operate Correctly - Left Rear
Refer to Wiring Diagrams Set 119, Climate Controlled Seats for schematic and connector information. Electrical Diagrams
Normal Operation
The heated seat module receives constant battery voltage. When the ignition is on and the driver heated seat button on the HVAC module is pressed, a momentary ground signal is sent to the heated seat module on command circuit to turn the system on or off. Upon receiving a signal, the heated seat module decreases one setting (the sequence is high, low, off, high). The heated seat module supplies voltage to the cushion and backrest heater mats. The cushion and backrest heater mats are connected in series and operate together. Temperature is maintained by a temperature sensor contained within the cushion heater mat. The heated seat module supplies a reference voltage to the temperature sensor and monitors the signal to control current flow to the heater mats.
This pinpoint test is intended to diagnose the following:
- Fuse(s)
- Wiring, terminals or connectors
- Heater mat
- Rear HVAC module
- Rear heated seat module
PINPOINT TEST U : THE HEATED SEAT IS INOPERATIVE/DOES NOT OPERATE CORRECTLY - LEFT REAR
U1 CHECK THE VOLTAGE TO THE REAR HEATED SEAT MODULE
- Disconnect: Heated Seat Module C3304B.
- Measure the voltage between:
- heated seat module C3304B-1, circuit SBP40 (VT/RD), harness side and ground.
Is the voltage greater than 10 volts?
Yes
GO to U2.
No
REPAIR the circuit. TEST the system for normal operation.
U2 CHECK LEFT REAR 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 U7.
No
GO to U3.
U3 CHECK LEFT REAR SEAT CUSHION HEATER CIRCUIT FOR AN OPEN AND SHORT TO GROUND
- Disconnect: Driver Seat Cushion Heater Mat C3167.
- Measure the resistance between:
- heated seat module C3304B-4, circuit CHS39 (GN/BU), harness side and driver seat cushion heater mat C3167-1, circuit CHS39 (GN/BU), harness side.
- heated seat module C3304B-4, circuit CHS39 (GN/BU), harness side and ground.
Is the resistance less than 5 ohms between heated seat module and cushion heater mat and greater than 10,000 ohms between the heated seat module and ground?
Yes
GO to U4.
No
REPAIR the circuit. TEST the system for normal operation.
U4 CHECK LEFT REAR HEATER MATS GROUND CIRCUIT FOR AN OPEN
- Disconnect: Backrest Heater Mat C3168.
- Measure the resistance between left rear backrest heater mat C3168-1, circuit GD149 (BK/GY), harness side and ground.
Is the resistance less than 5 ohms?
Yes
GO to U5.
No
REPAIR the circuit. TEST the system for normal operation.
U5 CHECK LEFT REAR CUSHION HEATER MAT FOR AN OPEN
- Measure the resistance between left rear cushion heater mat C3167 pins 1 and 4, component side.
Is the resistance between 0.6 and 2 ohms?
Yes
GO to U6.
No
INSTALL a new left rear cushion heater mat. REFER to Seat Cushion Heater Mat - Second Row, 40 Percent . TEST the system for normal operation.
U6 CHECK LEFT REAR 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
REPAIR circuit CHS40 (GY/VT). TEST the system for normal operation.
No
INSTALL a new rear seat backrest heater mat. REFER to Seat Backrest Heater Mat - Second Row, 40 Percent . TEST the system for normal operation.
U7 CHECK TEMPERATURE SENSOR CIRCUIT FOR A SHORT TO VOLTAGE
- Disconnect: Heated Seat Module C3304A.
- 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.
GO to U10 to check the temperature sensor.
TEST the system for normal operation.
No
GO to U8.
U8 CHECK HEATED SEAT TEMPERATURE SENSOR CIRCUITS FOR AN OPEN AND SHORT TO GROUND
- Ignition OFF.
- Measure the resistance between:
- rear heated seat module C3304A-3, circuit VHS42 (GN), harness side and C3304A-12, circuit RHS41 (GN/BN), 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-3 and ground?
Yes
GO to U11.
No
GO to U9.
U9 CHECK HEATED SEAT TEMPERATURE SENSOR CIRCUIT FOR AN OPEN AND SHORT TO GROUND
- Disconnect: Driver Seat Cushion Heater Mat C3167.
- Measure the resistance between:
- rear heated seat module C3304A-3, circuit VHS42 (GN), harness side and rear seat cushion heater mat C3167-2, 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 C3167-2, and greater than 10,000 ohms between C3304A-3 and ground?
Yes
GO to U10.
No
REPAIR the circuit. TEST the system for normal operation.
U10 CHECK TEMPERATURE SENSOR FOR AN OPEN
- Measure the resistance between rear heated seat cushion C3167 pin 2 and pin 3, 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 - Second Row, 40 Percent . TEST the system for normal operation.
U11 CHECK HEATED SEAT MODULE COMMAND CIRCUIT FOR SHORT TO VOLTAGE
- Disconnect: Rear HVAC C3198.
- Ignition ON.
- Measure the voltage between heated seat module C3304A-2, circuit CHS47 (VT/GN), harness side and ground.
Is any voltage present?
Yes
REPAIR the circuit. TEST the system for normal operation.
No
GO to U12.
U12 CHECK HEATED SEAT MODULE COMMAND CIRCUIT FOR A SHORT TO GROUND
- Ignition OFF.
- Measure the resistance between heated seat module C3304A-2, circuit CHS47 (VT/GN), harness side and ground.
Is the resistance greater than 10,000 ohms?
Yes
GO to U13.
No
REPAIR the circuit. TEST the system for normal operation.
U13 CHECK HEATED SEAT MODULE COMMAND CIRCUIT FOR AN OPEN
- Measure the resistance between heated seat module C3304A-2, circuit CHS47 (VT/GN), harness side and HVAC module C3198-16, circuit CHS47 (VT/GN), harness side.
Is the resistance less than 5 ohms?
Yes
GO to U14.
No
REPAIR the circuit. TEST the system for normal operation.
U14 CHECK THE HVAC MODULE OUTPUT
- Connect: HVAC Module C3198.
- Connect: Heated Seat Module C3304A.
- Connect: Heated Seat Module C3304B.
- Ignition ON.
- NOTE: The following measurement must be taken by back-probing the heated seat module C3304A.
NOTE: The voltage on circuit CHS47 (VT/GN) should drop momentarily when the driver heated seat control button is pressed.
Measure the voltage between heated seat module C3304A-2, circuit CHS47 (VT/GN), harness side and ground by back-probing heated seat module C3304A-2. Press the driver heated seat control button on the HVAC module and note the voltage.
Is the voltage greater than 10 volts before pressing the driver heated seat control button, then momentarily drops when the heated seat control button is pressed?
Yes
INSTALL a new heated seat module. REFER to Heated Seat Module - Rear . TEST the system for normal operation.
No
If the voltage is greater than 10 volts but did not drop when the driver heated seat button was pressed, INSTALL a new HVAC module.
If the voltage is less than 10 volts, INSTALL a new heated seat module. REFER to Heated Seat Module - Rear .
TEST the system for normal operation.