Schematic Reference: Diagnostic Starting Point - Automatic Transmission Shift Lock Control Automatic Transmission Shift Lock Control Schematics in Automatic Transmission - 6L80

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

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

Go to Step 2

Go to Symptoms - Automatic Transmission Shift Lock ControlSymptoms - Automatic Transmission Shift Lock Control in Automatic Transmission - 6L80

1. Apply the parking brake and block the wheels.
2. Turn ON the ignition, with the engine OFF.
3. Attempt to move the shift lever out of the PARK position.

Does the shift lever move out of the PARK position?

Go to Step 3

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

1. Disconnect the shift lock control relay.
2. Attempt to move the shift lever out of the PARK position.

Does the shift lever move out of the PARK position?

Go to Step 6

Go to Step 4

Test the shift lock control relay brake switch input circuit for an open or a high resistance. Refer to Circuit Testing Circuit Testing and Wiring Repairs Wiring Repairs in Wiring Systems.

Did you find and correct the condition?

Go to Step 11

Go to Step 5

Test the shift lock control relay ground circuit for an open or a high resistance. Refer to Circuit TestingCircuit Testing and Wiring Repairs Wiring Repairs in Wiring Systems.

Did you find and correct the condition?

Go to Step 11

Go to Step 7

Test the shift lock control solenoid feed circuit for a short to voltage. Refer to Circuit TestingCircuit Testing and Wiring Repairs Wiring Repairs in Wiring Systems.

Did you find and correct the condition?

Go to Step 11

Go to Step 8

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

Did you find and correct the condition?

Go to Step 11

Go to Step 9

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

Did you find and correct the condition?

Go to Step 11

Go to Step 10

Replace the shift lock control relay. Refer to Relay Replacement - Relay within an Electrical Center Relay Replacement in Wiring Systems.

Did you complete the repair?

Go to Step 11

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Replace the shift lock control solenoid. Refer to Automatic Transmission Shift Lock Control Actuator Replacement Automatic Transmission Shift Lock Actuator Replacement in Automatic Transmission - 6L80.

Did you complete the repair?

Go to Step 11

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Operate the system in order to verify the repair.

Did you find and correct the condition?

System OK

Go to Step 2