B2180
DTC B1935 or B2180
Diagnostic Instructions
* Perform the Diagnostic System Check - Vehicle (Initial Inspection and Diagnostic Overview) prior to using this diagnostic procedure.
* ReviewStrategy 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 0D
- Left Seat Back Heater Circuit Resistance Above Threshold
DTC 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/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
Heated/Cooled Seat Schematics (Electrical Diagrams)
Connector End View Reference
Component Connector End Views (Connector Views)
Description and Operation
Heated Seats Description and Operation (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
Control Module References (Programming and Relearning) for scan tool information
Circuit/System Testing
B1935 0D or B1935 0E
1. Ignition OFF, disconnect the X3 harness connector at the MSM.
2. Ignition ON, verify that a test lamp illuminates between the B+ circuit terminal 5 and ground.
• If the test lamp does not illuminate, test the B+ circuit for a short to ground or an open/high resistance.
3. Ignition OFF, connect the X3 harness connector at the MSM and disconnect the X1 harness connector at the MSM.
4. Test for 3.5-10 ohms between the control circuit terminal 14 and control circuit terminal 1.
• 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.
5. If all circuits test normal, replace the MSM.
B2180 0D or B2180 0E
1. Ignition OFF, disconnect the X3 harness connector at the MSM.
2. Ignition ON, verify that a test lamp illuminates between the B+ circuit terminal 5 and ground.
• If the test lamp does not illuminate, test the B+ circuit for a short to ground or an open/high resistance.
3. Ignition OFF, connect the X3 harness connector at the MSM and disconnect the X1 harness connector at the MSM.
4. Test for 3.5-10 ohms between the control circuit terminal 6 and control circuit terminal 4.
• 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.
5. If all circuits test normal, replace the MSM.
Repair Instructions
Perform the Diagnostic Repair Verification (Verification Tests) after completing the diagnostic procedure.
* Driver or Passenger Seat Back Cushion Heater Replacement (Driver or Passenger Seat Back Cushion Heater Replacement)
* Control Module References (Programming and Relearning) for MSM replacement, setup, and programming