Pinpoint Test E: The Brake Transmission Shift Interlock (BTSI) System Does Not Operate Properly

Refer to Transmission Controls - 10R80 for schematic and connector information.

Normal Operation and Fault Conditions

The brake transmission shift interlock (BTSI) system prevents the shift knob from leaving the park position unless certain conditions are met. To release the brake transmission shift interlock (BTSI), the ignition must be on and the brake pedal must be applied. When the ignition is on, the brake pedal is applied, and the PCM is not commanding the brake transmission shift interlock (BTSI) to be locked, the GSM will release the shift lock.

DTC Fault Trigger Conditions

DTC	Description	Fault Trigger Condition
GSM P0929:00	Gear Shift Lock Solenoid/Actuator Circuit 'A' Range/Performance: No Sub Type Information	This DTC indicates the GSM detected the maximum stall current in the shift interlock solenoid circuit.
GSM P0929:77	Gear Shift Lock Solenoid/Actuator Circuit 'A' Range/Performance: Commanded Position Not Reachable	This DTC indicates the GSM was unable to lock the rotary knob in the Park position.

Possible Causes

Discharged battery/charging system
Brake switch
Connectors damaged or pushed-out terminals, corrosion, loose wires and missing or damaged seals
GSM

E1 CHECK THE GSM (GEAR SHIFT MODULE) FOR DIAGNOSTIC TROUBLE CODES (DTCS)
- Using a diagnostic scan tool, retrieve all continuous memory diagnostic trouble codes (CMDTCs) from the GSM.
Are any system voltage or internal module diagnostic trouble codes (DTCs) present?

Yes RESOLVE those diagnostic trouble codes (DTCs) first. REFER to the DTC Chart.

No GO to E2

E2 CHECK THE OPERATION OF THE BRAKE TRANSMISSION SHIFT INTERLOCK (BTSI) SYSTEM
- Using a diagnostic scan tool, clear all diagnostic trouble codes (DTCs) from the GSM.
- Ignition OFF.
- Ignition ON.
- Repeat the following steps 3 times:
  - Press the brake pedal.
  - Select Drive.
  - Select Park.
  - Release the brake pedal.
  - Wait 1 minute.
  - With the brake pedal released, attempt to move the selector lever out of the Park position. The selector lever should be locked in the Park position with the brake pedal released.
Does the brake transmission shift interlock (BTSI) system operate correctly?

Yes GO to E4

No GO to E3

E3 CHECK THE OPERATION OF THE BRAKE SWITCH

Access the PCM and monitor the BOO1PID
- Press and release the brake pedal while observing PID BOO1.
Does the status of PID BOO1 change appropriately as the brake pedal is pressed and released?

Yes GO to E5

No RESOLVE any brake switch diagnostic trouble codes (DTCs) that are present in the PCM. REFER to the Appropriate DTC Chart.

E4 CHECK THE GSM (GEAR SHIFT MODULE) FOR DIAGNOSTIC TROUBLE CODES (DTCS)

NOTE: If a GSM self-test is carried out, the driver door must be fully closed. A false P166B DTC may set if the driver door is not fully closed during the self-test.
- Using a diagnostic scan tool, carry out the GSM self-test.
Is DTC P0929:00 and/or P0929:77 present?

Yes GO to E5

No The concern is not present at this time.

E5 CHECK FOR CORRECT GSM (GEAR SHIFT MODULE) OPERATION

Ignition OFF.

Disconnect and inspect the GSM connector.

Repair:
- corrosion (install new connector or terminals - clean module pins)
- damaged or bent pins - install new terminals/pins
- pushed-out pins - install new pins as necessary

Connect the GSM connector. Make sure it seats and latches correctly.

Operate the system and determine if the concern is still present.

Is the concern still present?

Yes

CHECK for an applicable TSB, GSB, SSM, or FSA. If a service bulletin exists for this concern, discontinue this test and follow bulletin instructions. If none address this concern, INSTALL a new GSM. REFER to: Gear Shift Module (GSM) . or REFER to: Gear Shift Module (GSM) - Vehicles With: 15.5 Inch Center Display Screen .

No	The system is operating correctly at this time. The concern may have been caused by module connections. ADDRESS the root cause of any connector or pin issues.