GM Service Manual Online
For 1990-2009 cars only

Step

Action

Value(s)

Yes

No

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

1

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

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Go to Step 2

Go to Diagnostic System Check - Automatic Transmission Shift Lock Control

2

  1. Connect a test lamp between the neutral safety switch park signal circuit at the auto trans shift lock control switch and a good ground.
  2. Turn ON the ignition, with the engine OFF.

Does the test lamp illuminate?

--

Go to Step 3

Go to Step 5

3

  1. Turn OFF the ignition.
  2. Connect a test lamp between the auto trans shift lock solenoid supply voltage circuit at the auto trans 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 16

4

  1. Turn OFF the ignition.
  2. Connect a test lamp between the auto trans shift lock solenoid supply voltage circuit at the auto trans 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 15

Go to Step 10

5

  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 data list.

Does the scan tool display ON?

--

Go to Step 6

Go to Step 22

6

  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 7

Go to Step 11

7

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

Does the test lamp illuminate?

--

Go to Step 8

Go to Step 12

8

  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 9

Go to Step 13

9

  1. Turn OFF the ignition.
  2. Connect a 10 amp fused jumper between the park relay switch side feed circuit and the neutral safety switch park signal circuit
  3. Turn ON the ignition, with the engine OFF.

Does the auto trans shift lock operate properly?

--

Go to Step 20

Go to Step 14

10

Repair the open or high resistance in the auto trans shift lock solenoid supply voltage circuit. Refer to Circuit Testing and Wiring Repairs in Wiring Systems.

Did you complete the repair?

--

Go to Step 24

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11

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 24

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12

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 24

--

13

Test for an open or high resistance 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 24

Go to Step 22

14

Repair the open or high resistance in the neutral safety switch park signal circuit. Refer to Circuit Testing and Wiring Repairs in Wiring Systems.

Did you complete the repair?

--

Go to Step 24

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15

Test for an open or high resistance in the auto trans shift lock control solenoid ground circuit. Refer to Circuit Testing and Wiring Repairs in Wiring Systems.

Did you find and correct the condition?

--

Go to Step 24

Go to Step 18

16

  1. Inspect the auto trans shift lock control switch adjustment. Refer to Stop Lamp Switch Adjustment and Stop Lamp Switch Replacement in brakes.
  2. Inspect for poor connections at the auto trans 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 24

Go to Step 17

17

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

Did you complete the replacement?

--

Go to Step 24

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18

  1. Inspect the auto trans shift lock control solenoid adjustment. Refer to Automatic Transmission Shift Lock Control Assemble - Off Vehicle in Steering Wheel and Column.
  2. 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 24

Go to Step 19

19

Replace the auto trans shift lock control solenoid. Refer to Automatic Transmission Shift Lock Control Disassemble - Off Vehicle and Automatic Transmission Shift Lock Control Assemble - Off Vehicle in Steering Wheel and Column.

Did you complete the replacement?

--

Go to Step 24

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20

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 24

Go to Step 21

21

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

Did you complete the replacement?

--

Go to Step 24

--

22

Inspect for poor connections at the harness connector of the 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 24

Go to Step 23

23

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 24

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24

Operate system in order to verify the repair.

Did you find and correct the condition?

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System OK

Go to Step 2