GM Service Manual Online
For 1990-2009 cars only

Step

Action

Yes

No

Schematic Reference: Diagnostic Starting Point - Automatic Transmission Shift Lock Control .

DEFINITION: Transmission shift lever does not move with ignition ON and the brake pedal pressed.

1

Did you perform the Symptoms - Automatic Transmission Shift Lock Control tests and perform all necessary inspections?

Go to Step 2

Go to Symptoms - Automatic Transmission Shift Lock Control

2

  1. Turn ON the ignition, with the engine OFF.
  2. Press and hold the brake pedal.
  3. Attempt to move the shift lever out of the PARK position.

Does the shift lever move out of the PARK position?

Go to Testing for Intermittent Conditions and Poor Connections

Go to Step 3

3

Do the stop lamps operate properly?

Go to Step 4

Go to Diagnostic Starting Point - Lighting

4

  1. Connect a test lamp between the shiftlock control solenoid feed circuit of the shiftlock control relay (terminal 4) and ground.
  2. Turn ON the ignition, with the engine OFF.
  3. Press and hold the brake pedal.

Does the test lamp illuminate?

Go to Step 7

Go to Step 5

5

Test the shift lock control relay supply voltage circuit for an open or high resistance. Refer to Circuit Testing and Wiring Repairs.

Did you find and correct the condition?

Go to Step 9

Go to Step 6

6

Test the shift lock control relay brake switch input circuit for a short to B+. Refer to Circuit Testing and Wiring Repairs.

Did you find and correct the condition?

Go to Step 14

Go to Step 10

7

Test the shift lock control solenoid feed circuit for an open or high resistance. Refer to Circuit Testing and Wiring Repairs.

Did you find and correct the condition?

Go to Step 14

Go to Step 8

8

Test the shift lock control solenoid supply voltage circuit for an open or high resistance. Refer to Circuit Testing and Wiring Repairs.

Did you find and correct the condition?

Go to Step 14

Go to Step 9

9

Test the shift lock control solenoid ground circuits for an open or high resistance. Refer to Circuit Testing and Wiring Repairs.

Did you find and correct the condition?

Go to Step 14

Go to Step 11

10

Inspect for poor connections at the shift lock control relay. Refer to Testing for Intermittent Conditions and Poor Connections and Connector Repairs.

Did you find and correct the condition?

Go to Step 14

Go to Step 12

11

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

Did you find and correct the condition?

Go to Step 14

Go to Step 13

12

Replace the shift lock control relay. Refer to Relay Replacement.

Did you complete the replacement?

Go to Step 14

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13

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

Did you complete the replacement?

Go to Step 14

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14

Operate the system in order to verify the repair.

Did you find and correct the condition?

System OK

Go to Step 2