GM Service Manual Online
For 1990-2009 cars only

Step

Action

Yes

No

Schematic Reference: Shift Lock Control Schematics

DEFINITION: Transmission shift lever does not lock in the PARK position with the ignition ON and the brake pedal not applied.

1

Did you perform the Auto Trans Shift Lock Control System Diagnostic System Check?

Go to Step 2

Go to Diagnostic System Check - Automatic Transmission Shift Lock Control

2

  1. Turn ON the ignition, with the engine OFF.
  2. Apply the parking brake and block the wheels.
  3. Attempt to move the shift lever out of the PARK position without depressing the brake pedal.

Does the shift lever move out of the PARK position?

Go to Step 3

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

3

  1. Turn OFF the ignition.
  2. Connect a test lamp between the automatic transmission shift lock control switch supply voltage circuit at the automatic transmission shift lock control switch and a good ground.
  3. Turn ON the ignition, with the engine OFF.

Does the test lamp illuminate?

Go to Step 4

Go to Step 7

4

  1. Turn OFF the ignition.
  2. Connect a test lamp between the automatic transmission shift lock solenoid supply voltage circuit at the automatic transmission shift lock control switch and a good ground.
  3. Turn ON the ignition, with the engine OFF.

Does the test lamp illuminate?

Go to Step 5

Go to Step 13

5

  1. Turn OFF the ignition.
  2. Connect a test lamp between the automatic transmission shift lock control solenoid supply voltage circuit at the automatic transmission shift lock control solenoid and a good ground.
  3. Turn ON the ignition, with the engine OFF.

Does the test lamp illuminate?

Go to Step 6

Go to Step 17

6

  1. Turn OFF the ignition.
  2. Connect a test lamp between the automatic transmission shift lock control solenoid supply voltage circuit and the automatic transmission shift lock control solenoid ground circuit at the automatic transmission shift lock control solenoid.
  3. Turn ON the ignition, with the engine OFF.

Does the test lamp illuminate?

Go to Step 14

Go to Step 18

7

  1. Install a scan tool.
  2. Turn ON the ignition, with the engine OFF.
  3. With a scan tool, observe the park relay status in the rear integration module (RIM) data list.

Does the scan tool display ON?

Go to Step 8

Go to Step 15

8

  1. Turn OFF the ignition.
  2. Disconnect the park relay.
  3. Connect a test lamp between the park relay coil side feed circuit and a good ground.
  4. Turn ON the ignition, with the engine OFF.

Does the test lamp illuminate?

Go to Step 9

Go to Step 19

9

Connect a test lamp between the park relay switch side feed circuit and a good ground.

Does the test lamp illuminate?

Go to Step 10

Go to Step 20

10

  1. Turn OFF the ignition.
  2. Connect a test lamp between the park relay coil side feed circuit and the park relay control circuit.
  3. Turn ON the ignition, with the engine OFF.
  4. With a scan tool command the park relay ON and OFF.

Does the test lamp turn ON and OFF with each command?

Go to Step 11

Go to Step 12

11

  1. Turn OFF the ignition.
  2. Connect a 10 amp fused jumper between the park relay switch side feed circuit and the automatic transmission shift lock control switch supply voltage circuit.
  3. Turn ON the ignition, with the engine OFF.
  4. Apply the parking brake and block the wheels.
  5. Attempt to move the shift lever out of the PARK position without depressing the brake pedal.

Did the shift lever move out of the PARK position?

Go to Step 21

Go to Step 16

12

Test the for an open or short to battery voltage in the park relay control circuit. Refer to Circuit Testing and Wiring Repairs in Wiring Systems.

Did you find and correct the condition?

Go to Step 26

Go to Step 15

13

Inspect for poor connections at the automatic transmission shift lock control switch. Refer to Testing for Intermittent Conditions and Poor Connections and Connector Repairs in Wiring Systems.

Did you find and correct the condition?

Go to Step 26

Go to Step 22

14

Inspect for poor connections at the auto trans shift lock control solenoid. Refer to Testing for Intermittent Conditions and Poor Connections and Connector Repairs in Wiring Systems.

Did you find and correct the condition?

Go to Step 26

Go to Step 23

15

Inspect for poor connections at the harness connector of the rear integration module (RIM). Refer to Testing for Intermittent Conditions and Poor Connections and Connector Repairs in Wiring Systems.

Did you find and correct the condition?

Go to Step 26

Go to Step 25

16

Inspect for poor connections at the park relay. Refer to Testing for Intermittent Conditions and Poor Connections and Connector Repairs in Wiring Systems.

Did you find and correct the condition?

Go to Step 26

Go to Step 24

17

Repair the open or short to ground in the automatic transmission shift lock control solenoid supply voltage circuit. Refer to Circuit Testing and Wiring Repairs in Wiring Systems.

Did you complete the repair?

Go to Step 26

--

18

Repair the open in the automatic transmission shift lock control solenoid ground circuit. Refer to Circuit Testing and Wiring Repairs in Wiring Systems.

Did you complete the repair?

Go to Step 26

--

19

Repair the open or high resistance in the park relay coil side feed circuit. Refer to Circuit Testing and Wiring Repairs in Wiring Systems.

Did you complete the repair?

Go to Step 26

--

20

Repair the open or high resistance in the park relay switch side feed circuit. Refer to Circuit Testing and Wiring Repairs in Wiring Systems.

Did you complete the repair?

Go to Step 26

--

21

Repair the open or high resistance in the automatic transmission shift lock control switch supply voltage circuit. Refer to Circuit Testing and Wiring Repairs in Wiring Systems.

Did you complete the repair?

Go to Step 26

--

22

Replace the automatic transmission shift lock control switch. Refer to Stop Lamp Switch Replacement in Hydraulic Brakes.

Did you complete the replacement?

Go to Step 26

--

23

Replace the automatic transmission shift lock control solenoid. Refer to Automatic Transmission Shift Lock Actuator Replacement .

Did you complete the replacement?

Go to Step 26

--

24

Replace the park relay. Refer to Wiring Repairs in Wiring Systems.

Did you complete the replacement?

Go to Step 26

--

25

Replace the rear integration module (RIM). Refer to Rear Integration Body Control Module Replacement in Body Control System.

Did you complete the replacement?

Go to Step 26

--

26

Operate the system in order to verify the repair.

Did you find and correct the condition?

System OK

Go to Step 2