Power Seats

DTC B1420

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 Descriptor
DTC B1420
- Device Voltage

Diagnostic Fault Information





Circuit/System Description

Battery positive voltage is supplied at all times to the memory seat module (MSM), the driver seat adjuster switch, and the memory seat adjuster switch from the TILT/TELE SW/MEM SEAT MOD 10A fuse located in the body control module (BCM) fuse block. The MSM monitors this voltage to verify that power is supplied to the seat adjuster switch before it will allow for any memory recall operation.

Conditions for Running the DTC

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

Conditions for Setting the DTC

DTC B1420 will set if the MSM detects an open on the B+ circuit.

Actions Taken When the DTC Sets

* The memory seat functions for the seat will be disabled.
* Manual seat functions will operate.

Conditions for Clearing the DTC

* 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

The MSM is also referred to as the Driver Position Module in certain scan tool menus.

Reference Information
Schematic Reference

Driver Seat Schematics (Driver Seat Schematics)
Connector End View Reference

Component Connector End Views (Connector Views)
Description and Operation

Memory Seats Description and Operation (Memory 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 Verification

Ignition ON, observe the scan tool Driver Position Module seat switch parameters while activating each switch. The reading should change between Inactive and Active as each switch is activated.

Circuit/System Testing

1. Ignition OFF, disconnect the X2 harness connector at the MSM.
2. Ignition ON, verify that a test lamp illuminates between the B+ circuit terminal F11 and ground.

• If the test lamp does not illuminate, test the B+ circuit for a short to ground or an open/high resistance.

3. If all circuits test normal, replace the MSM.

Repair Instructions

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

Control Module References (Programming and Relearning) for MSM replacement, setup, and programming