B1840

DTC B1830, B1835, B1840 or B1845

Diagnostic Instructions

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

DTC Descriptor

DTC B1830
- Driver Seat Lumbar Forward Switch Circuit

DTC B1835
- Driver Seat Lumbar Rearward Switch Circuit

Diagnostic Fault Information






Circuit/System Description

The power lumbar switches are inputs to the memory seat module (MSM). The seat module supplies the switch assembly with a battery positive switch supply circuit and monitor the switch signal circuits. In an inactive state the switch signal circuits are floating and when a switch is pressed the signal circuit is closed to the switch power circuit within the lumbar switch assembly. When battery voltage is present on the switch signal circuit the seat module determines the switch status to be active.

Conditions for Running the DTC

The battery voltage must be between 9-16 volts.

Conditions for Setting the DTC

A switch signal circuit to the MSM is active for more than 60 seconds.

Action Taken When the DTC Sets

The MSM will disable the power lumbar function.

Conditions for Clearing the DTC

* This DTC will clear on current status after the condition for setting the fault is corrected.
* A history DTC will clear after 100 consecutive ignition cycles without a fault present.

Circuit/System Verification

Ignition ON, observe the scan tool lumbar switch parameters while operating the lumbar switch in both directions. The reading should change between Inactive, Forward and Rearward.

Circuit/System Testing

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

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

3. Verify the scan tool switch parameter is Inactive.

^ If not the specified value, test the affected signal circuit terminal listed for a short to voltage. If the circuit tests normal, replace the memory seat module.

* Lumbar forward terminal A
* Lumbar rearward terminal D

4. Install a 3A fused jumper wire between the affected signal circuit terminal listed and the B+ circuit terminal E. Verify the scan tool switch parameter is the desired direction.

* Lumbar forward terminal A
* Lumbar rearward terminal D

^ If not the specified value, test the signal circuit for an open/high resistance. If the circuit tests normal, replace the memory seat module.

5. If all circuits test normal, test or replace the lumbar switch.

Repair Instructions

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

* Power Seat Switch Replacement