Diagnostic Starting Point - Automatic Transmission Shift Lock Control
Begin the system diagnosis with the Diagnostic System Check - Vehicle in Vehicle DTC Information. The Diagnostic System Check will provide the following information
- The identification of the control modules which command the system
- The ability of the control modules to communicate through the serial data circuit
- The identification of any stored diagnostic trouble codes (DTCs) and their status
The use of the Diagnostic System Check will identify the correct procedure for diagnosing the system and where the procedure is located.
Scan Tool Output Controls
| Scan Tool Output Control | Additional Menu Selection(s) | Description |
|---|---|---|
| Brake to Shift Relay | Special Functions-Output Control | Command turns ON and OFF the supply voltage to the shift lock control solenoid. Voltage is supplied to UNLOCK the shift lever. |
Scan Tool Output Controls
Scan Tool Data List
| Scan Tool Parameter | Data List | Units Displayed | Typical Data Value |
|---|---|---|---|
| Operating Conditions: Ignition ON, with the engine OFF. Transmission shift lever in the PARK position. | |||
| Battery 1 | Ignition | Volts | 0-25 V |
| Power Mode | Ignition | OFF/ACCY/RUN/CRANK | RUN |
| BTSI | Chassis Data | LOCKED/UNLOCKED | LOCKED |
Body Control Module (BCM)
Scheme 105
Circuit Description
The body control module (BCM) controls the automatic transmission (A/T) shift lock control solenoid by providing battery voltage to the solenoid. The BCM utilizes a smart driver to control the voltage supplied to the A/T shift lock control solenoid. The smart driver monitors the voltage and current flow of the control circuit. DTC B2707 will set when the BCM detects a short to ground, during the shift lock control solenoid operation.
DTC Descriptor
This diagnostic procedure supports the following DTC
DTC B2707 Gearshift Unlock Circuit Low
Conditions for Running the DTC
- The ignition switch is in the ON position.
- The brake pedal is depressed.
- The transmission the PARK position.
Conditions for Setting the DTC
The BCM detects the shift lock control solenoid control circuit is grounded for a minimum of one second.
Action Taken When the DTC Sets
The BCM disables shift lock control solenoid operation until the next key cycle.
Conditions for Clearing the DTC
- A current DTC B2707 will clear when the malfunction is no longer present and the ignition switch is cycled.
- All BCM history codes will clear after 100 ignition cycles with no current codes active during the 100 ignition cycles.
Diagnostic Aids
- If the A/T shift lock control circuit is shorted to ground, the A/T shift lock control solenoid will be inoperative. The shift lever will not shift out of PARK position with the brake pedal depressed.
- Perform the tests while wiggling the wires and connectors. This may often cause an intermittent malfunction to appear. Refer to «Testing for Intermittent Conditions and Poor Connections»(ref-196941-S32978396082005101000000) in Wiring Systems.
The body control module (BCM) controls the automatic transmission (A/T) shift lock control solenoid by providing battery voltage to the solenoid. The BCM utilizes a smart driver to control the voltage supplied to the A/T shift lock control solenoid. The smart driver monitors the voltage and current flow of the control circuit. DTC B2709 will set when the BCM detects an open circuit during the shift lock control solenoid operation.
This diagnostic procedure supports the following DTC
DTC B2709 Gearshift Unlock Circuit Open
- The ignition switch is in the ON position.
- The brake pedal is depressed.
- The transmission the PARK position.
The BCM detects an open at the shift lock control solenoid output driver for a minimum of one second.
The BCM disables shift lock control solenoid operation until the next key cycle.
- A current DTC B2709 will clear when the malfunction is no longer present and the ignition switch is cycled.
- All BCM history codes will clear after 100 ignition cycles with no current codes active during the 100 ignition cycles.
- If the A/T shift lock control circuit is shorted to battery positive voltage, the A/T shift lock control solenoid will be unlocked. The vehicle will shift out of PARK, without depressing the brake pedal.
- Perform the tests while wiggling the wires and connectors. This may often cause an intermittent malfunction to appear. Refer to «Testing for Intermittent Conditions and Poor Connections»(ref-196941-S32978396082005101000000) in Wiring Systems.
Visual/Physical Inspection
- Inspect for aftermarket devices which could affect the operation of the automatic transmission shift lock control system. Refer to «Checking Aftermarket Accessories»(ref-196941-S26961180052005101000000) in Wiring Systems.
- Inspect the easily accessible or visible system components for obvious damage or conditions which could cause the symptom.
Symptom List
Refer to a symptom diagnostic procedure from the following list in order to diagnose the symptom
- «Shift Lever Does Not Move with Brake Pedal Depressed»(ref-196998-S12306901092005101000000)
- «Shift Lever Can Be Moved without Brake Pedal Depressed»(ref-196998-S08537011582005101000000)