B2165

DTC B1920 or B2165

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 B1920
- Driver Seat Heater Timer Circuit

DTC B2165
- Front Passenger Seat Heater Timer Circuit




Diagnostic Fault Information






Circuit/System Description

The heated seat temperature sensor is located in the seat cushion just under the seat cover within the seat heating element. The body control module (BCM) supplies the heated seat temperature sensor with a temperature sensor signal circuit and a temperature sensor low reference circuit. The BCM monitors the voltage of the heated seat temperature sensor signal circuit to determine the temperature of the seat. The BCM cycles the heated seat relay on and off in order to maintain the desired seat temperature based on the voltage feedback from the temperature sensor.


The BCM also monitors the sensor signal circuit for a change in voltage that is either to fast or to slow. The slow rate check is performed only when the heated seat is initially turned on with a cold seat in order to prevent setting a false DTC.


Conditions for Running the DTC

* DTC B1327 must not be present.
* Battery voltage must be between 9-16 volts.



Conditions for Setting the DTC

B1920

The DTC will set when the BCM detects that the change in voltage of the driver temperature sensor signal circuit is either to slow or to fast.

B2165

The DTC will set when the BCM detects that the change in voltage of the passenger temperature sensor signal circuit is either to slow or to fast.


Actions Taken When the DTC Sets

The heated seat system for the affected seat will be disabled.


Conditions for Clearing the DTC

* The current DTC will clear and set to history 3 seconds after the reference voltage returns to the normal operating range.
* The condition responsible for setting the DTC no longer exists.
* A history DTC will clear once 50 consecutive malfunction-free ignition cycles have occurred.



Diagnostic Aids

* When DTC B1920 or B2165 are set as current, the BCM disables the heated seat function not allowing any heated seat relay control functions to occur. Cycling the ignition OFF then ON will reset the DTC and allow relay commands.
* Due to the nature of DTC B1920 and B2165, it may take up to 10 minutes for the DTCs to set. For purposes of testing in this diagnostic procedure the DTCs must be cleared or inactive.
* Faults to other heated seat system circuits other than the temperature sensor signal circuit may also cause DTC B1920 and B2165 to set.



Reference Information
Schematic Reference

Heated/Cooled Seat Schematics (Electrical Diagrams)
Connector End View Reference

Component Connector End Views (Connector Views)
Description and Operation

Heated Seats Description and Operation (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

Control Module References (Programming and Relearning)


Circuit/System Testing

1. Ignition OFF, disconnect the appropriate heated seat relay.
2. Ignition ON, verify that a test lamp does not illuminate between the control circuit terminal C1 and ground.

• If the test lamp illuminates, test the control circuit for a short to voltage.

3. Verify that a test lamp illuminates between the B+ circuit terminal A2 and ground.

• If the test lamp does not illuminate, test the B+ circuit for a short to ground or an open/high resistance. If the circuit tests normal and the B+ circuit fuse is open, test the control circuit terminal C1 for a short to ground.

4. Ignition OFF, test for less than 5.0 ohms of resistance between the ground circuit terminal C2 and ground.

• If greater than the specified range, test the ground circuit for an open/high resistance.

5. Ignition OFF, test for less than 5.0 ohms of resistance between the relay controlled output circuit terminal C1 and ground.

• If greater than the specified range, test the relay controlled output circuit terminal C1 for an open/high resistance.

6. Connect a test lamp between the relay control circuit terminal A1 and ground.
7. Command the appropriate heated seat ON and OFF with a scan tool. The test lamp should turn ON and OFF when changing between the commanded states.

• If the test lamp is always ON, test the control circuit for a short to voltage. If the circuit tests normal, replace the BCM.


• If the test lamp is always OFF, test the control circuit for a short to ground or an open/high resistance. If the circuit tests normal, replace the BCM.

8. Ignition OFF, disconnect the harness connector at the appropriate heated seat element.
9. Ignition OFF, test for less than 5.0 ohms of resistance between the low reference circuit terminal C and ground.

• If greater than the specified range, test the low reference circuit for an open/high resistance. If the circuit tests normal, replace the BCM.

10. Ignition ON, test for 9.8-10.2 volts between the signal circuit terminal B 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 BCM.


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

11. If all circuits test normal, test or replace the appropriate heated seat element.



Repair Instructions

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

* Driver Seat and Passenger Seat Cushion Heater Replacement (Driver Seat and Passenger Seat Cushion Heater Replacement)
* Control Module References (Programming and Relearning) for BCM replacement, setup, and programming