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B2180




DTC B1935 or B2180

Diagnostic Instructions

* Perform the Diagnostic System Check - Vehicle Diagnostic System Check - Vehicle prior to using this diagnostic procedure.
* Review Strategy Based Diagnosis Strategy Based Diagnosis for an overview of the diagnostic approach.
* Diagnostic Procedure Instructions Diagnostic Procedure Instructionsprovides 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 0D
- Left Seat Back Heater Circuit Resistance Above Threshold

DTC B1935 0E
- Left Seat Back Heater Circuit Resistance 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 0D
- Right Seat Back Heater Circuit Resistance Above Threshold

DTC B2180 0E
- Right Seat Back Heater Circuit Resistance 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 heated seat module (HSM) 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 HSM must be powered and the heated seat must be enabled.

Conditions for Setting the DTC

B1935 04 or B2180 04

The module does not detect a temperature change within 210 seconds.

B1935 0A or B2180 0A

The module detects that the set point temperature has not been reached within 8.5 minutes.

B1935 0B, B1935 0E, B2180 0B, or B2180 0E

By measuring output current, the module calculates that the heating element resistance is below the minimum resistance.

B1935 0C, B1935 0D, B2180 0C, or B2180 0D

By measuring output current, the module calculates that the heating element resistance is above the maximum resistance.

B1935 1F or 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.

Reference Information
Schematic Reference

Heated/Cooled Seat Schematics [1][2]Electrical Diagrams
Connector End View Reference

Component Connector End Views Connector End Views By Name
Description and Operation

Heated Seats Description and Operation
Electrical Information Reference

* Circuit Testing Circuit Testing
* Connector Repairs Connector Repairs
* Testing for Intermittent Conditions and Poor Connections Testing for Intermittent Conditions and Poor Connections
* Wiring Repairs Wiring Repairs

Scan Tool Reference

Control Module References Programming and Relearningfor scan tool information

Circuit/System Testing

B1935 0A, B1935 0B, B1935 0C, B1935 0D, B1935 0E, B1935 04, or B1935 1F
1. Ignition OFF, disconnect the X1 harness connector at the HSM.

Important: Element resistance must be measured twice to ensure that all failure conditions are simulated. First with the seat unoccupied, then with the seat occupied.


2. Test for 3.5 - 11.5 Ohms between control circuit terminal 3 and control circuit terminal 1.

• If less than the specified range, test for a short between the control circuits. If the circuits test normal, replace the seat back heater element.
• If greater than the specified range, test the control circuits for an open/high resistance. If the circuits test normal, replace the seat back heater element.

3. Disconnect the X2, X4 harness connectors at the HSM.
4. Test for 850 Ohms - 300 kOhms between the signal circuit terminal 19 X4 and the low reference circuit terminal 5 X2.

• 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 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.

5. Connect the X1, X2, X4 harness connectors at the HSM.
6. Disconnect the harness connector at the seat back heater element/temperature sensor.
7. Ignition ON, test for 4.8 - 5.2 V between the signal circuit terminal C and ground.

• 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 HSM.
• If greater than the specified range, test the signal circuit for a short to voltage. If the circuit tests normal, replace the HSM.

8. If all circuits test normal, replace the HSM.

B2180 0A, B2180 0B, B2180 0C, B2180 0D, B2180 0E, B2180 04, or B2180 1F
1. Ignition OFF, disconnect the X1 harness connector at the HSM.

Important: Element resistance must be measured twice to ensure that all failure conditions are simulated. First with the seat unoccupied, then with the seat occupied.


2. Test for 3.5 - 11.5 Ohms between control circuit terminal 6 and control circuit terminal 4.

• If less than the specified range, test for a short between the control circuits. If the circuits test normal, replace the seat back heater element.
• If greater than the specified range, test the control circuits for an open/high resistance. If the circuits test normal, replace the seat back heater element.

3. Disconnect the X2, X4 harness connectors at the HSM.
4. Test for 850 Ohms - 300 kOhms between the signal circuit terminal 10 X4 and the low reference circuit terminal 7 X2.

• 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 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.

5. Connect the X1, X2, X4 harness connectors at the HSM.
6. Disconnect the harness connector at the seat back heater element/temperature sensor.
7. Ignition ON, test for 4.8 - 5.2 V between the signal circuit terminal C and ground.

• If greater than the specified range, test the signal circuit for a short to voltage. If the circuit tests normal, replace the HSM.
• 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 HSM.

8. If all circuits test normal, replace the HSM.

Repair Instructions

Perform the Diagnostic Repair Verification Verification Tests after completing the diagnostic procedure.

* Driver or Passenger Seat Back Cushion Heater Replacement
* Control Module References Programming and Relearningfor the HSM replacement, setup, and programming

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