Pinpoint Test T: The Heated Seats are Inoperative - Rear

Seats

Pinpoint Test T: The Heated Seats are Inoperative - Rear

Refer to Wiring Diagrams Set 119, Climate Controlled Seats for schematic and connector information. Electrical Diagrams

Normal Operation

When ignition voltage is supplied and the driver or passenger heated seat button on the rear HVAC module is pressed, a momentary ground signal is sent to the heated seat module to command 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 monitors temperature sensors contained within the cushion heater mats on the left and right rear seats. The temperature sensors share a common return circuit to the heated seat module. If the temperature sensor return circuit opens (resistance greater than 300,000 ohms), the heated seat module disables the outputs to both seats. The system remains disabled until the circuit is repaired and the heated seat module is reset by cycling the ignition OFF and ON.

This pinpoint test is intended to diagnose the following:

- Fuse(s)

- Wiring, terminals or connectors

- Heated seat module

PINPOINT TEST T : THE HEATED SEATS ARE INOPERATIVE - REAR

T1 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 SBP40 (VT/RD), harness side and ground.






Are the voltages greater than 10 volts?

Yes
GO to T2.

No
VERIFY Smart Junction Box (SJB) fuses 40 (20A) and 35 (10A) are OK. If OK, REPAIR the affected circuit. If not OK, REFER to the Wiring Diagrams to identify the possible causes of the circuit short. TEST the system for normal operation. Electrical Diagrams

T2 CHECK THE HEATED SEAT MODULE GROUND CIRCUIT FOR AN OPEN

- Ignition OFF.

- Measure the resistance between heated seat module C3304B-5, circuit GD133 (BK), harness side and ground.





Is the resistance less than 5 ohms?

Yes
GO to T3.

No
REPAIR the circuit. TEST the system for normal operation.

T3 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 any voltage present on either circuit?

Yes
REPAIR the affected circuit. TEST the system for normal operation.

No
GO to T4.

T4 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 T5.

No
REPAIR the affected circuit. TEST the system for normal operation.

T5 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
GO to T6.

No
REPAIR circuit RHS41. TEST the system for normal operation.

T6 CHECK THE HVAC MODULE OUTPUT

- 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.