Diagnostic Instructions
| • | Perform the Diagnostic System Check - Vehicle prior to using this diagnostic procedure. |
| • | Review Strategy Based Diagnosis for an overview of the diagnostic approach. |
| • | Diagnostic Procedure Instructions provides an overview of each diagnostic category. |
DTC Descriptors
DTC B2435 02: Left Seat Back Heater Sensor Circuit Short to GroundDTC B2435 05: Left Seat Back Heater Sensor Circuit Short to Battery or Open
DTC B2440 02: Right Seat Back Heater Sensor Circuit Short to Ground
DTC B2440 05: Right Seat Back Heater Sensor Circuit Short to Battery or Open
Diagnostic Fault Information
Circuit | Short to Ground | Open/High Resistance | Short to Voltage | Signal Performance |
|---|---|---|---|---|
B+ MSM Terminal 5 C3 | 1, 2, B1935 0C, B1935 0D, B2180 0C, B2180 0D, B2425 0C, B2425 0D, B2430 0C, B2430 0D | 1, 2, B1935 0C, B1935 0D, B2180 0C, B2180 0D, B2425 0C, B2425 0D, B2430 0C, B2430 0D | -- | -- |
Driver Heated Seat Back Element Supply Voltage | B2508 02 | B1935 0C, B1935 0D | B2345 00, B2508 01 | B1935 0B, B1935 0E |
Driver Heated Seat Back Element Control | B2345 00, B2508 02 | B1935 0C, B1935 0D | B2345 00, B2508 01 | B1935 0B, B1935 0E |
Driver Heated Seat Back Temperature Sensor Signal | B2435 02 | B1935 04, B1935 1F, B2435 0D | B1935 04, B1935 1F, B2435 0D | B1935 0A, B2345 13, B2345 42, B2345 4B |
Driver Heated Seat Back Temperature Sensor Low Reference | -- | B1935 04, B1935 1F, B2435 0D | -- | B2345 13, B2345 42, B2345 4B |
Driver Heated Seat Cushion Element Supply Voltage | B2508 02 | B2425 0C, B2425 0D | B2345 00, B2508 01 | B2425 0B, B2425 0E |
Driver Heated Seat Cushion Element Control | B2345 00, B2508 02 | B2425 0C, B2425 0D | B2345 00, B2508 01 | B2425 0B, B2425 0E |
Driver Heated Seat Cushion Temperature Sensor Signal | B1925 02, B2425 1F | B1925 05, B2425 04, B2425 1F | B1925 05, B2425 04, B2425 1F | B2345 13, B2345 42, B2345 4B, B2425 0A |
Driver Heated Seat Cushion Temperature Sensor Low Reference | -- | B1925 05, B2425 04, B2425 1F | -- | B2345 13, B2345 42, B2345 4B |
Passenger Heated Seat Back Element Supply Voltage | B2508 02 | B2180 0C, B2180 0D | B2345 00, B2508 01 | B2180 0B, B2180 0E |
Passenger Heated Seat Back Element Control | B2345 00, B2508 02 | B2180 0C, B2180 0D | B2345 00, B2508 01 | B2180 0B, B2180 0E |
Passenger Heated Seat Back Temperature Sensor Signal | B2440 02 | B2180 04, B2180 1F, B2440 05 | B2180 04, B2180 1F, B2440 05 | B2180 0A, B2345 13, B2345 42, B2345 4B |
Passenger Heated Seat Back Temperature Sensor Low Reference | -- | B2180 04, B2180 1F, B2440 05 | -- | B2345 13, B2345 42, B2345 4B |
Passenger Heated Seat Cushion Element Supply Voltage | B2508 02 | B2430 0C, B2430 0D | B2345 00, B2508 01 | B2430 0B, B2430 0E |
Passenger Heated Seat Cushion Element Control | B2345 00, B2508 02 | B2430 0C, B2430 0D | B2345 00, B2508 01 | B2430 0B, B2430 0E |
Passenger Heated Seat Cushion Temperature Sensor Signal | B2170 02, B2430 1F | B2430 04, B2430 1F, B2170 05 | B2430 04, B2430 1F, B2170 05 | B2345 13, B2345 42, B2345 4B, B2430 0A |
Passenger Heated Seat Cushion Temperature Sensor Low Reference | -- | B2430 04, B2430 1F, B2170 05 | -- | B2345 13, B2345 42, B2345 4B |
1. Power seat inoperative 2. Heated seat inoperative | ||||
Circuit/System Description
The heated seat temperature sensor is located in the seat back just under the seat cover with the seat heating element. The temperature sensor is a 2 wire thermistor and resistance through the sensor varies with temperature. The signal circuit is referenced from 5 volts within the memory seat module (MSM) and the temperature of the seat surface determines the signal circuit voltage. Once the seat reaches the set temperature, the module will then cycle the control circuits of the heating elements ON and OFF in order to maintain the desired seat temperature based on the feedback voltage from the sensors.
Conditions for Running the DTC
The MSM must be powered.
Conditions for Setting the DTC
The temperature sensor voltage drops below 0.8 volt for more than 1 second.
Action Taken When the DTC Sets
The heated seat back function for the appropriate seat will be disabled.
Conditions for Clearing the DTC
| • | The current DTC will clear 3 seconds after the reference voltage returns to normal operating range, and the ignition is cycled OFF then back to ACC or RUN. |
| • | The history DTC will clear after 50 consecutive fault-free ignition cycles have occurred. |
Reference Information
Schematic Reference
Connector End View Reference
Heated/Cooled Seat Connector End Views
Electrical Information Reference
Scan Tool Reference
Circuit/System Testing
B2435 02 or B2435 05
- Ignition OFF, disconnect the C2, C5 harness connectors at the MSM.
- Test for 850-300K ohms between the signal circuit terminal 4 C5 and the low reference circuit terminal 2 C2.
- Connect the C2, C5 harness connectors at the MSM.
- Disconnect the harness connector at the seat back heater element/temperature sensor.
- Ignition ON, test for 4.8-5.2 volts between the signal circuit terminal C and ground.
- If all circuits test normal, replace the MSM.
Important: When measuring the resistance, the resistance values are based on the seat being at room temperature of 20°C (68°F).
| ⇒ | If greater than the specified range, test the signal and low reference circuits for a short to voltage or an open/high resistance. If the circuits test normal, replace the seat back heater element/temperature sensor. |
| ⇒ | If less than the specified range, test for a short between the signal and low reference circuits. If the circuits test normal, replace the seat back heater element/temperature sensor. |
| ⇒ | If greater than the specified range, test the signal circuit for a short to voltage. If the circuit tests normal, replace the MSM. |
| ⇒ | If less than the specified range, test the signal circuit for a short to ground or an open/high resistance. If the circuit tests normal, replace the MSM. |
B2440 02 or B2440 05
- Ignition OFF, disconnect the C2, C5 harness connectors at the MSM.
- Test for 850-300K ohms between the signal circuit terminal 3 C5 and the low reference circuit terminal 5 C2.
- Connect the C2, C5 harness connectors at the MSM.
- Disconnect the harness connector at the seat back heater element/temperature sensor.
- Ignition ON, test for 4.8-5.2 volts between the signal circuit terminal C and ground.
- If all circuits test normal, replace the MSM.
Important: When measuring the resistance, the resistance values are based on the seat being at room temperature of 20°C (68°F).
| ⇒ | If greater than the specified range, test the signal and low reference circuits for a short to voltage or an open/high resistance. If the circuits test normal, replace the seat back heater element/temperature sensor. |
| ⇒ | If less than the specified range, test for a short between the signal and low reference circuits. If the circuits test normal, replace the seat back heater element/temperature sensor. |
| ⇒ | If greater than the specified range, test the signal circuit for a short to voltage. If the circuit tests normal, replace the MSM. |
| ⇒ | If less than the specified range, test the signal circuit for a short to ground or an open/high resistance. If the circuit tests normal, replace the MSM. |
Repair Instructions
Perform the Diagnostic Repair Verification after completing the diagnostic procedure.
| • | Control Module References for the MSM replacement, setup, and programming |
