GM Service Manual Online
For 1990-2009 cars only

Circuit Description

The mobility seat module uses inputs from 4 limit switches in order to determine the seat position. The limit switch signal circuits are referenced from battery voltage within the module. The limit switches will open or close the switch signal circuits to ground in order for the module to determine them to be active or inactive. The swivel out limit switch signal circuit is considered to be active when the circuit reference voltage is low or closed to ground by the switch.

DTC Descriptor

This diagnostic procedure supports the following DTC:

DTC 021 Swivel Out Limit Switch Active at Start of Rotation Out

Conditions for Running the DTC

    • Battery voltage must be within 9-16 volts.
    • Seat operation is attempted from the forward facing position.

Conditions for Setting the DTC

When seat operation is attempted from the forward facing position the swivel out limit switch signal to the module is low or active.

Action Taken When the DTC Sets

While the fault is current the module will not allow the seat to be rotated out of the forward facing position.

Conditions for Clearing the DTC

The DTC may be cleared by removing the main power supply or ground from the seat module.

Diagnostic Aids

Inspect the limit switch for any physical damage or obstructions to its mechanical operation which may cause the condition.

Step

Action

Yes

No

Schematic Reference: Power Seats Schematics

1

Did you review the description and operation and perform the necessary inspections?

Go to Step 2

Go to Symptoms - Seats

2

Verify the fault is present.

Does the system operate normally?

Go to Testing for Intermittent Conditions and Poor Connections in Wiring Systems

Go to Step 3

3

  1. Disconnect the swivel out limit switch connector.
  2. Attempt to operate the seat to the swivel out hard stop.

Does the seat operate to the swivel out hard stop?

Go to Step 6

Go to Step 4

4

Test the swivel out limit switch signal circuit for a short to ground. Refer to Circuit Testing and Wiring Repairs in Wiring Systems.

Did you find and correct the condition?

Go to Step 7

Go to Step 5

5

Replace the mobility seat control module. Refer to Control Module References in Computer/Integrating Systems for replacement, setup, and programming.

Is the repair complete?

Go to Step 7

--

6

Replace the mobility seat base unit. Refer to Sit-N-Lift Seat Base Replacement .

Is the repair complete?

Go to Step 7

--

7

Operate the system in order to verify the repair.

Did you correct the condition?

System OK

Go to Step 3