When I start engine and depress brake pedal and go to move shift lever I can't depress shift lever button to move out of park. This will happen 6 times out 10.

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:
?€¢
The automatic transmission shift lock control solenoid

?€¢
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

1. Turn ON the ignition.
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

1. Turn OFF the ignition.
2. Disconnect the automatic transmission shift lock control switch.
3. Turn ON the ignition, with the engine OFF.
4. 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

1. Turn OFF the ignition.
2. Leave the automatic transmission shift lock control switch disconnected.
3. 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.
4. Turn ON the ignition with the engine OFF.

Does the test lamp illuminate?

5

1. Turn OFF the ignition.
2. Connect a test lamp between the ignition 1 voltage circuit of the park lock 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 9

6

1. Turn OFF the ignition.
2. Connect a test lamp between the ignition 1 voltage circuit of the park lock solenoid and the park lock solenoid ground circuit.
3. 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
--

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
--

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
--

14

Operate the system in order to verify the repair.
Did you correct the condition?
System OK
Go to Step 2

Automatic Transmission Shift Lock Control Description and Operation.
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:
• The automatic transmission shift lock solenoid (serviced as the automatic transmission shift lock actuator), as well as the body control module (BCM) and the engine control module (ECM). The shift lock solenoid is located within the floor shift control assembly with vehicles equipped with floor shift.
• The BCM controls the voltage supply circuit of the shift lock control solenoid. The following conditions must be met before the BCM will supply voltage to the shift lock control solenoid.
The BCM controls the voltage to the shift lock control solenoid through the shift lock control solenoid controlled voltage circuit. The following conditions must be met before the BCM will supply voltage to the shift lock solenoid:
• The ignition is in the ON position.
• The ECM sends an input via GMLAN serial data to the BCM indicating the transmission is in the PARK position.
• The BCM determines the brake pedal is applied according the brake pedal position.
Since the shift lock control solenoid is permanently grounded, the BCM supplies voltage to the automatic transmission shift lock control solenoid, mechanically unlocking the shift lever allowing the driver to move the shift lever out of the PARK position as the solenoid energizes. When the brake pedal is not applied, the BCM turns the control voltage output of the shift lock control solenoid OFF, de-energizing the shift lock control solenoid. The de-energized solenoid mechanically locks the shift lever in the PARK position.
During remote start operation, the BCM will de-energize the shift lock control circuit, locking the shift lever in the PARK position.
Circuit/System Description
The body control module (BCM) controls the shift lock solenoid by providing battery voltage to the shift lock control solenoid. The BCM utilizes a smart driver to control the voltage supplied to the shift lock solenoid. The smart driver monitors the voltage and current flow of the control circuit.
Diagnostic Aids
• Use a scan tool to verify there are no brake pedal position sensor and/or transmission internal mode switch (IMS) DTCs set that could cause the BCM not to provide battery voltage to the A/T shift lock solenoid.
• If the automatic transmission shift lock control circuit is shorted to battery positive voltage, the A/T shift lock solenoid will be inoperative. The vehicle will shift out of PARK without depressing the brake pedal.
Your best bet is have it towed to a repair shop !

Set the emergency brake.

Locate the shifter lock override slot located on the shifter console near the shifter lever. Normally, the slot is plugged with a small plastic cap.

Remove the plastic cap covering the override slot and insert a key, nail file or similarly shaped object into the slot and push down.

While pushing down, depress the brake pedal, grab the shifter and push in the shifter lock button located on the shifter as you normally do and then move the shifter to the Neutral position. With the brake pedal still depressed, start the engine with the shifter in the Neutral position.

Automatic Transmission Shift Lock Control System
The automatic transmission shift lock control is a safety device that prevents an inadvertent shift out of PARK when the ignition is ON. The driver must press the brake pedal before moving the shift lever out of the PARK position. The system consists of the following components:
?€¢
The automatic transmission shift lock control solenoid.

?€¢
The automatic transmission shift lock control switch.

?€¢
The park/neutral position switch.

With the ignition in the ON position, battery positive voltage is supplied to the park/neutral position switch. When the transmission is in the PARK position the contacts in the park/neutral position switch are closed. This allows current to flow through the switch to the automatic transmission shift lock control switch. The circuit continues through the normally-closed 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, locking the shift linkage in the PARK position. When the driver presses the brake pedal the contacts in the automatic transmission shift lock control switch open, causing the automatic transmission shift lock control solenoid to release. This allows the shift lever to move from the PARK position.
Park Lock Solenoid
The park lock solenoid is a safety device that prevents an inadvertent shift out of PARK when the key is in the OFF position. The key must be in the RUN position to release the park lock solenoid. The system consists of the park lock solenoid. With the ignition in the ON position, voltage is supplied to the park lock solenoid. The park lock solenoid energizes through a permanent ground unlocking the shift lever. With the ignition in the OFF or ACCY position the park lock solenoid de-energizes and locks the shift lever in the park position.
Shift Lever Does Not Move with Brake Pedal Depressed
DEFINITION: Transmission shift lever will not move out of the PARK position with the ignition ON and the brake pedal pressed.

1

Did you perform the Symptoms - Automatic Transmission Shift Lock Control tests and all the necessary inspection?
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 in Wiring Systems
NO Go to Step 3

3

1. Turn OFF the ignition.
2. Disconnect the automatic transmission shift lock control switch.
3. Turn ON the ignition, with the engine OFF.
4. Press and hold the brake pedal.
5. Attempt to move the transmission shift lever out of the PARK position.

Does the transmission shift lever move out of the PARK position?
Go to Step 6
Go to Step 4

4

1. Turn OFF the ignition.
2. Disconnect the automatic transmission shift lock control solenoid.
3. Turn ON the ignition, with the engine OFF
4. Press and hold the brake pedal.
5. Attempt to move the transmission shift lever out of the PARK position.

Does the transmission shift lever move out of the PARK position?
Go to Step 7
Go to Step 5
Inspect for poor connections at the harness connector of the automatic transmission 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 10
Go to Step 9

6

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 10
Go to Step 8

7

Repair the short to battery positive voltage in the A/T 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 10
--

8

Replace the automatic transmission shift lock control switch. Refer to Stop Lamp Switch Replacement in Lighting Systems.
Did you complete the replacement?

Shift interlock problem . do you know what that is ?
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:
• The automatic transmission shift lock control solenoid
• 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.
Park Lock Solenoid
The park lock solenoid is a safety device that prevents an inadvertent shift out of PARK when the key is in the OFF position. The key must be in the RUN position to release the park lock solenoid.
The system consists of the park lock solenoid.
With the ignition in the ON position, voltage is supplied to the park lock solenoid. The park lock solenoid energizes through a permanent ground unlocking the shift lever. With the ignition in the OFF or ACCY position the park lock solenoid de-energizes and locks the shift lever in the park position.

Shift Lever Does Not Move with Brake Pedal Depressed
Step
Action
Yes
No
Schematic Reference: Shift Lock Control Schematics
Connector End View Reference: Shift Lock Control Connector End Views or Automatic Transmission Related Connector End Views
DEFINITION: Transmission shift lever does not move out of the PARK position with the ignition ON and the brake pedal pressed.
1
Did you perform the symptom table tests and necessary inspections?
YES - Go to Step 2
NO - Go to Symptoms - Automatic Transmission Shift Lock Control
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?
YES - Go to Testing for Intermittent Conditions and Poor Connections
NO - 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?
YES - Go to Step 7
NO - 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?
YES - Go to Step 10
NO - Go to Step 5
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?
YES - Go to Step 6
NO - 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?
YES - Go to Step 8
NO - 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 .
Did you find and correct the condition?
YES - Go to Step 14
NO - 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 .
Did you find and correct the condition?
YES - Go to Step 14
NO - 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 .
Did you complete the repair?
Go to Step 14
--
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 .
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 .
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
--
13
Replace the automatic transmission shift lock control switch. Refer to Stop Lamp Switch Replacement .
Did you complete the replacement?
Go to Step 14
--
14
Operate the system in order to verify the repair.
Did you correct the condition?
System OK

Hi there,

Some automatic vehicles rely on the brake switch (mounted on brake pedal) to be activated by depressing brake pedal. This signal then operates a relay and switch, to release the gear lever.

Firstly, I would check the brake pedal switch (are your brake lights working?).

If brake switch is confirmed OK, then inspect the relay (and related circuit components) of the gear release switch.

If the floor shift lever wont move out of park, there foot brake lock that prevents it from moving until you depress the brake pedal and pull it out of park. I think the release is vacuum operated so try depressing the brake pedal a few time while trying to release. TerBo

In the area of the shifter (in the center console), there is a shift lock solenoid that is activated by the brake switch. This solenoid prevents shifting out of the Park position unless the brake pedal is depressed. Your problem could be either the brake switch or the solenoid. I would try replacing the switch first.

There may be a malfunction in the shift interlock sys.
This sys. keeps the shift from being moved from park
unless the brake peddle is depressed. There are 5 fuse's, directly or indirectly related to the interlock system. Fuse #6 15amp in the fuse box under the hood on the left side. The next 4 are in the fuse box
behind the left side of the dash. Fuse #3 15amp/fuse
#18 15amp/fuse #16 20amp and fuse #4 15amp.
Check these first, before you move on to the brake
light switch, under the dash at the brake peddle.
And the shift lock solenoid, under the console left of
the shift lever. Hope this helps.

The shift interlock does not allow the car to shift out of park unless the brake pedal is depressed.  Quick fix is with the car running to set the parking brake and turn the car to off and remover the key.  Put the key back in and turn one click to on.  Shift the car into neutral and you can start the car and go.  The repair for this is either the brake switch located on the brake pedal being replaced.  I had a broken wire leading to the switch that caused the problem.  It also can be a blown fuse.