B1935
DTC B1935 or B2180
Diagnostic Instructions
* Perform the Diagnostic System Check - Vehicle prior to using this diagnostic procedure. Initial Inspection and Diagnostic Overview
* 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 04
- Left Seat Back Heater Circuit Open
DTC B1935 0A
- Left Seat Back Heater Circuit Rate of Change Below Threshold
DTC B1935 0B
- Left Seat Back Heater Circuit Current Above Threshold
DTC B1935 0C
- Left Seat Back Heater Circuit Current Below Threshold
DTC B1935 1F
- Left Seat Back Heater Circuit Intermittent
DTC B2180 04
- Right Seat Back Heater Circuit Open
DTC B2180 0A
- Right Seat Back Heater Circuit Rate of Change Below Threshold
DTC B2180 0B
- Right Seat Back Heater Circuit Current Above Threshold
DTC B2180 0C
- Right Seat Back Heater Circuit Current Below Threshold
DTC B2180 1F
- Right Seat Back Heater Circuit Intermittent
Diagnostic Fault Information
Circuit/System Description
When the heated seat function is active, the memory seat module (MSM) supplies battery voltage through the element supply voltage circuit to the seat heater elements. The module controls the seat temperature by providing a PWM ground through the heated seat element control circuit to the seat heater elements. The module then monitors the current flow through the heating element and the temperature sensor rate of change to verify correct operation.
Conditions for Running the DTC
The memory seat module must be powered.
Conditions for Setting the DTC
B1935 04, B2180 04
The module does not detect a temperature change within 210 seconds.
B1935 0A, B2180 0A
The module detects that the set point temperature has not been reached within 8.5 minutes.
B1935 0B, B2180 0B
By measuring output current, the module calculates that the heating element resistance is below the minimum resistance.
B1935 0C, B2180 0C
By measuring output current, the module calculates that the heating element resistance is above the maximum resistance.
B1935 1F, B2180 1F
The temperature sensor voltage is erratic or changes suddenly.
Action Taken When the DTC Sets
The heated seat back function for the affected seat will be disabled.
Conditions for Clearing the DTC
* The current DTC clears 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.
Circuit/System Testing
1. Ignition OFF, disconnect the MSM connector C1.
2. Verify less than 15 ohms of resistance through the seat back heater element from the voltage supply circuit terminal to the low side drive control circuit terminal in the harness connector.
• If the resistance is greater than 15 ohms test the supply and control circuits for an open/high resistance. If the circuits test normal replace the seat back heater element.
3. Disconnect the MSM connectors C2 and C5.
4. Verify the resistance through the seat back heat sensor is 850-300K ohms from the signal circuit terminal to the low reference circuit terminal in the harness connectors.
• If greater than 300K ohms, test the signal circuit and low reference circuit for an open/high resistance. If the circuits test normal, replace the seat back heater element.
• If less than 850 ohms, replace the seat back heater element.
5. Connect the MSM connectors C1, C2, and C5.
6. Disconnect the seat back heater element connector.
7. Ignition ON, verify that the heat sensor signal circuit voltage from the MSM is not greater than 5 volts.
• If the signal circuit is greater than 5 volts test for a short to voltage. If the circuit tests normal replace the MSM.
8. If the circuits test normal replace the seat back heater element.
Repair Instructions
Perform the Diagnostic Repair Verification after completing the diagnostic procedure. Verification Tests
* Driver Seat and Passenger Seat Back Cushion Heater Replacement
* Control Module References for the MSM replacement, setup, and programming Programming and Relearning