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 B1935 0D: Left Seat Back Heater Circuit Resistance Above ThresholdDTC B1935 0E: Left Seat Back Heater Circuit Resistance Below Threshold
DTC B2180 0D: Right Seat Back Heater Circuit Resistance Above Threshold
DTC B2180 0E: Right Seat Back Heater Circuit Resistance Below Threshold
Diagnostic Fault Information
Circuit | Short to Ground | Open/High Resistance | Short to Voltage | Signal Performance |
|---|---|---|---|---|
Driver Heated Seat Back Element Supply Voltage | B2508 02 | B1935 0D | B2508 01 | B1935 0E |
Driver Heated Seat Back Element Control | B2508 02 | B1935 0D | B2508 01 | B1935 0E |
Driver Heated Seat Back Temperature Sensor Signal | B2435 02 | B2435 05 | B2435 05 | B2345 13, B2345 42, B2345 4B |
Driver Heated Seat Back Temperature Sensor Low Reference | -- | B2435 05 | -- | B2345 13, B2345 42, B2345 4B |
Driver Heated Seat Cushion Element Supply Voltage | B2508 02 | B2425 0D | B2508 01 | B2425 0E |
Driver Heated Seat Cushion Element Control | B2508 02 | B2425 0D | B2508 01 | B2425 0E |
Driver Heated Seat Cushion Temperature Sensor Signal | B1925 02 | B1925 05 | B1925 05 | B2345 13, B2345 42, B2345 4B |
Driver Heated Seat Cushion Temperature Sensor Low Reference | -- | B1925 05 | -- | B2345 13, B2345 42, B2345 4B |
Passenger Heated Seat Back Element Supply Voltage | B2508 02 | B2180 0D | B2508 01 | B2180 0E |
Passenger Heated Seat Back Element Control | B2508 02 | B2180 0D | B2508 01 | B2180 0E |
Passenger Heated Seat Back Temperature Sensor Signal | B2440 02 | B2440 05 | B2440 05 | B2345 13, B2345 42, B2345 4B |
Passenger Heated Seat Back Temperature Sensor Low Reference | -- | B2440 05 | -- | B2345 13, B2345 42, B2345 4B |
Passenger Heated Seat Cushion Element Supply Voltage | B2508 02 | B2430 0D | B2508 01 | B2430 0E |
Passenger Heated Seat Cushion Element Control | B2508 02 | B2430 0D | B2508 01 | B2430 0E |
Passenger Heated Seat Cushion Temperature Sensor Signal | B2170 02 | B2170 05 | B2170 05 | B2345 13, B2345 42, B2345 4B |
Passenger Heated Seat Cushion Temperature Sensor Low Reference | -- | B2170 05 | -- | B2345 13, B2345 42, B2345 4B |
Circuit/System Description
The left and right front passenger heated seats are controlled by the memory seat module (MSM). When active, power is applied to the seat cushion and back heater elements through a common voltage supply circuit. Each individual heater element is grounded by the MSM through separate low side drive control circuits. The heater element control circuits are pulse width modulated to ground by the module in order to control the seat temperatures by regulating the current flow through the heater elements. The module then monitors the current flow through the heating elements and the of rate change of the temperature sensor to verify correct heated seat operation.
Conditions for Running the DTC
The MSM is powered and the heated seat must be enabled.
Conditions for Setting the DTC
B1935 0D, B2180 0D
By measuring the current and voltage output to the seat back heating element every 10 seconds, the MSM calculates that the heating element resistance is above the maximum resistance value of 10 ohms.
B1935 0E, B2180 0E
By measuring the current and voltage output to the seat back heating element every 10 seconds, the MSM calculates that the heating element resistance is below the minimum resistance value of 3.5 ohms.
Action Taken When the DTC Sets
The heated seat function for the affected seat will be disabled.
Conditions for Clearing the DTC
| • | The current DTC will clear and will the set code to history, when the malfunction is no longer present and the power mode changes to 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
Description and Operation
Heated Seats Description and Operation
Electrical Information Reference
Scan Tool Reference
Control Module References for scan tool information
Circuit/System Testing
B1935 0D or B1935 0E
- Ignition OFF, disconnect the X3 harness connector at the MSM.
- Ignition ON, verify that a test lamp illuminates between the B+ circuit terminal 5 and ground.
- Ignition OFF, connect the X3 harness connector at the MSM and disconnect the X1 harness connector at the MSM.
- Test for 3.5-10 ohms between the control circuit terminal 14 and control circuit terminal 1.
- If all circuits test normal, replace the MSM.
| ⇒ | If the test lamp does not illuminate, test the B+ circuit for a short to ground or an open/high resistance. |
| ⇒ | If greater than the specified range, test the control circuits for an open/high resistance. If the circuits test normal, replace the seat back heating element. |
| ⇒ | If less than the specified range, test for a short between the control circuits. If the circuits test normal, replace the seat back heating element. |
B2180 0D or B2180 0E
- Ignition OFF, disconnect the X3 harness connector at the MSM.
- Ignition ON, verify that a test lamp illuminates between the B+ circuit terminal 5 and ground.
- Ignition OFF, connect the X3 harness connector at the MSM and disconnect the X1 harness connector at the MSM.
- Test for 3.5-10 ohms between the control circuit terminal 6 and control circuit terminal 4.
- If all circuits test normal, replace the MSM.
| ⇒ | If the test lamp does not illuminate, test the B+ circuit for a short to ground or an open/high resistance. |
| ⇒ | If greater than the specified range, test the control circuits for an open/high resistance. If the circuits test normal, replace the seat back heating element. |
| ⇒ | If less than the specified range, test for a short between the control circuits. If the circuits test normal, replace the seat back heating element. |
Repair Instructions
Perform the Diagnostic Repair Verification after completing the diagnostic procedure.
| • | Control Module References for MSM replacement, setup, and programming |
