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B2180



DTC B1935 or B2180

Diagnostic Instructions

* Perform the Diagnostic System Check - Vehicle (Initial Inspection and Diagnostic Overview) prior to using this diagnostic procedure.
* Review Strategy Based Diagnosis (Initial Inspection and Diagnostic Overview) for an overview of the diagnostic approach.
* Diagnostic Procedure Instructions (Initial Inspection and Diagnostic Overview) 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

The left and right rear passenger heated seats are controlled by the rear heated seat module. 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 heated seat module 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 heated seat system must be active.


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 the current and voltage output to the seat back heating element, the rear heated seat module calculates that the heating element resistance is below the minimum resistance value of 4.3 ohms.

B1935 0C, B2180 0C

By measuring the current and voltage output to the seat back heating element, the rear heated seat module calculates that the heating element resistance is above the maximum resistance value of 10.4 ohms.

B1935 1F, B2180 1F

The temperature sensor voltage is erratic or sudden change.


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 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 (Electrical Diagrams)
Connector End View Reference

Component Connector End Views (Connector Views)
Description and Operation

Rear Heated Seats Description and Operation (Rear Heated Seats Description and Operation)
Electrical Information Reference

* Circuit Testing (Component Tests and General Diagnostics)
* Connector Repairs (Component Tests and General Diagnostics)
* Testing for Intermittent Conditions and Poor Connections (Component Tests and General Diagnostics)
* Wiring Repairs (Component Tests and General Diagnostics)

Scan Tool Reference

Programming and Relearning (Programming and Relearning) for Scan Tool Information


Circuit/System Testing


B1935 Left Rear Seat Back
1. Ignition OFF, disconnect the X1 harness connector at the rear heated seat module.
2. Test for less than 10.4 ohms between the seat back supply voltage circuit terminal 3 and the control circuit terminal 1.

• If greater than the specified range, test the supply voltage circuit and the control circuit for an open/high resistance. If the circuits test normal, replace the seat back heating element.

3. Ignition OFF, disconnect the X2, X4 harness connectors at the rear heated seat module.
4. Test for 1.4K-300K ohms between the seat back temperature sensor signal circuit terminal 19 X4 and the low reference circuit terminal 5 X2.

• If greater than the specified range, test the signal circuit and low reference circuit for a short to voltage or an open/high resistance. If the circuits test normal, replace the seat back 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 temperature sensor.

5. Ignition OFF, connect the X1, X2, X4 harness connectors at the heated seat module.
6. Disconnect the harness connector at the seat back heating element/temperature sensor.
7. Ignition ON, test for 4.8-5.2 volts between the temperature sensor 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 heated seat module.
• If less than the specified range, test the signal circuit for a short to ground. If the circuit tests normal, replace the heated seat module.

8. If all circuits test normal, replace the rear heated seat module.



B2180 Right Rear Seat Back
1. Ignition OFF, disconnect the X1 harness connector at the rear heated seat module.
2. Test for less than 10.4 ohms between the seat back supply voltage circuit terminal 6 and the control circuit terminal 4.

• If greater than the specified range, test the supply voltage circuit and the control circuit for an open/high resistance. If the circuits test normal, replace the seat back heating element.

3. Ignition OFF, disconnect the X2, X4 harness connector at the rear heated seat module.
4. Test for 1.4K-300K ohms between the seat back temperature sensor signal circuit terminal 10 X4 and the low reference circuit terminal 7 X2.

• If greater than the specified range, test the signal circuit and low reference circuit for a short to voltage or an open/high resistance. If the circuits test normal, replace the seat back 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 temperature sensor.

5. Ignition OFF, connect the X1, X2, X4 harness connectors at the heated seat module.
6. Disconnect the harness connector at the seat back heating element/temperature sensor.
7. Ignition ON, test for 4.8-5.2 volts between the temperature sensor 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 heated seat module.
• If less than the specified range, test the signal circuit for a short to ground. If the circuit tests normal, replace the heated seat module.

8. If all circuits test normal, replace the rear heated seat module.



Repair Instructions

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

* Rear Seat Back Cushion Heater Replacement (Rear Seat Back Cushion Heater Replacement)
* Programming and Relearning (Programming and Relearning) for the rear heated seat module replacement, setup, and programming


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