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 body control module (BCM)
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The powertrain control module (PCM)
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 control solenoid:
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The ignition is in the ON position.
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The PCM sends a class 2 message to the BCM indicating the transmission is in the PARK position.
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The BCM determines the brake pedal is not applied according to the stop lamp switch.
When the ignition is in the ON position, the ignition 1 fuse supplies voltage to the automatic transmission shift lock control solenoid as the BCM supplies a ground to the control circuit, mechanically locking the shift lever in the PARK position as the solenoid energizes. When the brake pedal is applied, the BCM turns the ground of the control circuit OFF, de-energizing the shift lock control solenoid. The de-energized solenoid releases the mechanical lock allowing the driver to move the shift lever out of the PARK position. When the transmission is out of the PARK position, the shift lock control solenoid remains de-energized.
Your best bet is to take it to the dealer ,may have DTC'S
DTC B2707 Gearshift Unlock Circuit Low
The body control module (BCM) controls the automatic transmission shift lock control solenoid by providing a controlled ground to the automatic transmission shift lock control solenoid. The BCM utilizes a smart driver to monitor the voltage and current flow of the automatic transmission shift lock control solenoid control circuit. DTC B2707 will set when the BCM detects a short to ground when the solenoid is in the OFF state.
DTC B2708 Gearshift Unlock Circuit High
Did you perform the Diagnostic System Check - Vehicle?
Go to Step 2
Go to Diagnostic System Check - Vehicle in Vehicle DTC Information
2
- Turn ON the ignition, with the engine OFF.
- 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 in Wiring Systems
Go to Step 3
3
- Turn OFF the ignition.
- Install a scan tool.
- Turn ON the ignition, with the engine OFF.
- Press and hold the brake pedal.
- With a scan tool, command the Brake to Shift Relay output control parameter On.
- Attempt to move the shift lever out of the PARK position.
Does the shift lever move out of the PARK position?
Go to Step 4
Go to Step 6
4
- With the scan tool, observe the Brake Switch parameter in the powertrain control module (PCM) data display list.
- Press and release the brake pedal several times while observing the scan tool.
Does the brake input display Applied and Released with the brake pedal operation?
Go to Step 5
Go to
Diagnostic Starting Point - Lighting Systems in Lighting Systems
5
With the scan tool observe the TR Sw. parameter in the body control module (BCM) data list.
Does the scan tool indicate PARK position?
Go to Step 9
Go to
Scan Tool Data List in Engine Controls - 3.4L
6
- Turn OFF the ignition.
- Disconnect the harness connector of the automatic transmission shift lock control solenoid.
- Turn ON the ignition, with the engine OFF.
- 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 Step 7
Go to Step 8
7
Test the controlled ground circuit of the automatic transmission shift lock control solenoid for a short to ground. Refer to
Circuit Testing and
Wiring Repairs in Wiring Systems.
Did you find and correct the condition?
Go to Step 12
Go to Step 9
8
Inspect for poor connections as 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 12
Go to Step 10
9
Inspect for poor connections at the harness connector of the BCM. 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 12
Go to Step 11
10
Replace the automatic transmission shift lock control solenoid. Refer to
Shift Lock Control Solenoid Replacement .
Did you complete the replacement?
Go to Step 12
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11
Replace the BCM. Refer to
Control Module References in Computer/Integrating Systems for replacement, setup and programming.
Did you complete the replacement?
Go to Step 12
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12
Operate the system in order to verify the repair.
Did you find and correct the condition?
System OK
Go to Step 3
Your best bet