GM Service Manual Online
For 1990-2009 cars only

Diagnostic Instructions

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

Diagnostic Fault Information

Circuit

Short to Ground

Open/High Resistance

Short to Voltage

Signal Performance

Left Front Door Ajar Switch Signal

1

2

2

--

Left Rear Door Ajar Switch Signal

1

2

2

--

Right Front Door Ajar Switch Signal

1

2

2

--

Right Rear Door Ajar Switch Signal

1

2

2

--

Driver Door Lock Ground

--

2

2

--

LR Door Lock Ground

--

2

2

--

Front Passenger Door Lock Ground

--

2

2

--

RR Door Lock Ground

--

2

2

--

1. Door Ajar Indicator Always Illuminated

2. Door Ajar Indicator Inoperative

Circuit/System Description

The body control module (BCM) monitors each door ajar circuit to indicate the status of the door. When the respective door is opened, the door ajar signal circuit is switched to ground by the door lock ajar indicator switch, the BCM detects the drop in voltage in the circuit and then communicates this status to the instrument panel cluster (IPC) via a serial data message. The IPC, upon receipt of this serial data message, will illuminate the appropriate ajar message in the driver information center (DIC) and when the transaxle is shifted out of PARK, the DIC will also send a serial data message to the radio to activate the door ajar audible warning.

Reference Information

Schematic Reference

Door Lock/Indicator Schematics

Connector End View Reference

Component Connector End Views

Description and Operation

Power Door Locks Description and Operation

Electrical Information Reference

    •  Circuit Testing
    •  Connector Repairs
    •  Testing for Intermittent Conditions and Poor Connections
    •  Wiring Repairs

Scan Tool Reference

Control Module References for scan tool information

Circuit/System Verification

  1. Ignition ON, with all doors closed, observe the scan tool LF Door Ajar Switch and RF Door Ajar parameters while opening and closing the driver and front passenger doors. The parameter should change between Door Closed and Ajar.
  2. If the parameters do not change, refer to Front Door Ajar Malfunction.
  3. Observe the scan tool Left Rear Door Ajar Sw. and Right Rear Door Ajar Sw. parameters while opening and closing the rear passenger doors. The parameter should change between Closed and Ajar.
  4. If the parameters do not change, refer to Rear Door Ajar Malfunction.

Circuit/System Testing

Front Door Ajar Malfunction

  1. Ignition OFF, disconnect the harness connector at the appropriate front door lock.
  2. Test for less than 1.0 ohm between the ground circuit terminal listed below and ground.
  3. • Driver door lock ground circuit terminal 8
    • Front passenger door lock ground circuit terminal 3
    If greater than the specified range, test the ground circuit for an open/high resistance.
  4. Ignition ON, verify the scan tool LF Door Ajar Switch or RF Door Ajar parameter is Door Closed.
  5. If not the specified value, test the signal circuit terminal listed below for a short to ground.
    • Driver door lock signal circuit terminal 6
    • Front passenger door lock signal circuit terminal 1
    If the circuit tests normal, replace the BCM.
  6. Install a 3A fused jumper wire between the signal circuit terminal listed below and ground. Verify the scan tool LF Door Ajar Switch or RF Door Ajar parameter is Ajar.
  7. • Driver door lock signal circuit terminal 6
    • Front passenger door lock signal circuit terminal 1
    If not the specified value, test the signal circuit for a short to voltage or an open/high resistance. If the circuit tests normal, replace the BCM.
  8. If all circuits test normal, test or replace the front door lock.

Rear Door Ajar Malfunction

  1. Ignition OFF, disconnect the harness connector at the appropriate rear door lock.
  2. Test for less than 1.0 ohm between the ground circuit terminal listed below and ground.
  3. • LR door lock ground circuit terminal 6
    • RR door lock ground circuit terminal 3
    If greater than the specified range, test the ground circuit for an open/high resistance.
  4. Ignition ON, verify the scan tool Left Rear Door Ajar Sw. or Right Rear Door Ajar Sw. parameter is Closed.
  5. If not the specified value, test the signal circuit terminal listed below for a short to ground.
    • LR door lock signal circuit terminal 4
    • RR door lock signal circuit terminal 1
    If the circuit tests normal, replace the BCM.
  6. Install a 3A fused jumper wire between the signal circuit terminal listed below and ground. Verify the scan tool Left Rear Door Ajar Sw. or Right Rear Door Ajar Sw. parameter is Ajar.
  7. • LR door lock signal circuit terminal 4
    • RR door lock signal circuit terminal 1
    If not the specified value, test the signal circuit for a short to voltage or an open/high resistance. If the circuit tests normal, replace the BCM.
  8. If all circuits test normal, test or replace the rear door lock.

Component Testing

  1. Ignition OFF, disconnect the harness connector at the appropriate door lock.
  2. Test for infinite resistance between the signal terminal and the ground terminal with the door lock in the open position listed below.
  3. • Driver door lock terminal 6 and 8
    • Front passenger door lock terminal 1 and 3
    • LR door lock terminal 4 and 6
    • RR door lock terminal 1 and 3
    If not the specified value, replace the door lock.
  4. Test for less than 2.0 ohms between the signal terminal and the ground terminal with the door lock in the closed position listed below.
  5. • Driver door lock terminal 6 and 8
    • Front passenger door lock terminal 1 and 3
    • LR door lock terminal 4 and 6
    • RR door lock terminal 1 and 3
    If greater than the specified range, replace the door lock.

Repair Instructions

Perform the Diagnostic Repair Verification after completing the diagnostic procedure.

    •  Front Side Door Lock Replacement
    •  Rear Door Lock Replacement
    •  Control Module References for BCM replacement, setup, and programming