Seats

DTC B1420

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 Instructions) 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 seat adjuster switch from the TELE SWITCH/MSM fuse located in the body control module (BCM) fuse block. The memory seat module (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 memory seat module is also referred to as the Driver Position Module in certain scan tool menus.

Reference Information
Schematic Reference

Driver Seat Schematics ()
Connector End View Reference

Component Connector End Views (Connector Views)
Description and Operation

Memory 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 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 B11 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 seat adjuster switch signal circuits for a short to ground.

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

Repair Instructions

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

* Power Seat Switch Replacement ()
* Control Module References (Programming and Relearning) for MSM replacement, setup, and programming