Automatic Transmission Shift Lock Control System
The automatic transmission shift lock control system is a safety device that prevents an inadvertent shift out of PARK when the engine is running. The driver must press the brake pedal before moving the shift lever out of the PARK position. The system consists of the following components:
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The automatic transmission shift lock control solenoid
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The automatic transmission shift lock control switch
With the ignition in the ON position, voltage is supplied to automatic transmission shift lock control switch. Voltage flows through the normally closed contacts of the automatic transmission shift lock control switch to the automatic transmission shift lock control solenoid. The automatic transmission shift lock control solenoid is permanently grounded. This energizes the automatic transmission shift lock control solenoid causing the transmission shift lever to be physically locked in the PARK position. When the brake pedal is pressed the contacts in the automatic transmission shift lock control switch open, de-energizing the automatic transmission shift lock control solenoid. This allows the shift lever to be move out of the PARK position.
Shift Lever Does Not Move with Brake Pedal Depressed ?
2
- Turn ON the ignition.
- Press and hold the brake pedal.
- 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
- Turn OFF the ignition.
- Disconnect the automatic transmission shift lock control switch.
- Turn ON the ignition, with the engine OFF.
- Attempt to move the shift lever out of the PARK position.
Does the shift lever move out of the PARK position?
Go to Step 7
Go to Step 4
4
- Turn OFF the ignition.
- Leave the automatic transmission shift lock control switch disconnected.
- Connect a test lamp between the A/T shift lock control solenoid supply voltage circuit at the automatic transmission shift lock control solenoid and a good ground.
- Turn ON the ignition with the engine OFF.
Does the test lamp illuminate?
5
- Turn OFF the ignition.
- Connect a test lamp between the ignition 1 voltage circuit of the park lock solenoid and a good ground.
- Turn ON the ignition with the engine OFF.
Does the test lamp illuminate?
Go to Step 6
Go to Step 9
6
- Turn OFF the ignition.
- Connect a test lamp between the ignition 1 voltage circuit of the park lock solenoid and the park lock solenoid ground circuit.
- Turn ON the ignition with the engine OFF.
Does the test lamp illuminate?
Go to Step 8
Go to Step 11
7
Inspect for poor connections at the harness connector of 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 14
Go to Step 13
8
Inspect for poor connections at the harness connector of the park lock/automatic transmission shift lock control solenoid assembly. 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 14
Go to Step 12
9
Repair the open or high resistance in the park lock solenoid ignition 1 voltage circuit. Refer to
Circuit Testing or
Wiring Repairs in Wiring Systems.
Did you complete the repair?
Go to Step 14
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10
Repair short to battery positive voltage in the A/T shift lock control solenoid supply voltage circuit. Refer to
Circuit Testing or
Wiring Repairs in Wiring Systems.
Did you complete the repair?
Go to Step 14
--
11
Repair the open or high resistance in the park lock solenoid ground circuit. Refer to
Circuit Testing or
Wiring Repairs in Wiring Systems.
Did you complete the repair?
Go to Step 14
--
12
Important: Depress the button on the side of the shift lock actuator. With the button is depressed, cycle the plastic straw within the shift lever 3 to 5 times. The straw should move smoothly and freely except near the top of the travel where additional force will be required to mechanically actuate the park lock mechanism inside of the shift lock actuator. If there is stick/slip or abnormal friction while cycling the plastic straw or if the straw is altogether stuck in the lever, the entire control assembly (shifter and shift lock actuator) needs to be replaced. Refer to
Transmission Control Replacement . If there is no abnormal friction, replace the shift lock actuator. Refer to
Automatic Transmission Shift Lock Control Actuator Replacement .
Did you complete the replacement?
Go to Step 14
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13
Replace the automatic transmission shift lock control switch. Refer to
Stop Lamp Switch Replacement in Lighting Systems.
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 correct the condition?
System OK
Go to Step 2
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