Shift Interlock System: Diagnosis Pontiac Sunfire I

Diagnostic Starting Point - Automatic Transmission Shift Lock Control

Begin the system diagnosis with the DIAGNOSTIC SYSTEM CHECK - AUTOMATIC TRANSMISSION SHIFT LOCK CONTROL . The Diagnostic System Check will provide the following information

1. The identification of the control module(s) which command the system
2. The ability of the control module(s) to communicate through the serial data circuit.
3. 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.

Circuit Description

The body control module (BCM) controls the automatic transmission shift lock control solenoid. Battery positive voltage is supplied to the automatic transmission shift lock control solenoid. The BCM controls the automatic transmission shift lock control solenoid ground circuit. When the driver pressed the brake pedal the BCM removes the ground for the automatic transmission shift lock control solenoid. The solenoid de-energizes and releases the mechanical lock allowing the shift lever to be moved out of the PARK position.

Conditions for Running the DTC

1. The ignition switch is in the ON position.
2. The brake pedal is depressed.

Conditions for Setting the DTC

The automatic transmission shift lock control is open or shorted to ground for a minimum of 5 seconds.

Action Taken When the DTC Sets

1. If the shift lock control circuit is open, the automatic transmission shift lock control solenoid will be inoperative.
2. If the shift lock control circuit is shorted to ground, the automatic transmission shift lock control solenoid will always be engaged with the ignition ON.

Conditions for Clearing the DTC

1. A current DTC B2707 will clear when the malfunction is no longer present.
2. All BCM history codes will clear after 100 ignition cycles with no current codes active during the 100 ignition cycles.

Diagnostic Aids

Perform the tests while wiggling the wires and connectors. This may often cause an intermittent malfunction to appear. Refer to TESTING FOR INTERMITTENT AND POOR CONNECTIONS .

The body control module (BCM) controls the automatic transmission shift lock control solenoid. Positive voltage is supplied via the ignition 1 voltage circuit to the automatic transmission shift lock control solenoid. The BCM controls the ground circuit of the automatic transmission shift lock control solenoid. When the brake pedal is depressed, the BCM removes the ground allowing the solenoid to disengage. This action allows the vehicle to be shifted out of the PARK position.

1. The ignition switch is in the ON position.
2. The brake pedal is depressed.

The A/T shift lock control circuit is shorted to battery positive voltage for 1 second.

The BCM disables the A/T shift lock control output for the remainder of the ignition cycle.

1. A current DTC B2708 will clear when the malfunction is no longer present and the ignition switch is cycled.
2. All BCM history codes will clear after 100 ignition cycles with no current codes active during the 100 ignition cycles.

1. If the A/T shift lock control circuit is shorted to battery positive voltage, the automatic transmission shift lock control solenoid will be inoperative. The vehicle will shift out of PARK without depressing the brake pedal.
2. Perform the tests while wiggling the wires and connectors. This may often cause an intermittent malfunction to appear. Refer to TESTING FOR INTERMITTENT AND POOR CONNECTIONS .

Visual/Physical Inspection

1. Inspect for aftermarket devices which could affect the operation of the automatic transmission shift lock control. Refer to CHECKING AFTERMARKET ACCESSORIES in Wiring Systems.
2. 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

1. «SHIFT LEVER DOES NOT MOVE WITH BRAKE PEDAL DEPRESSED»(ref-189102-S12981178352005090600000) .
2. «SHIFT LEVER CAN BE MOVED WITHOUT BRAKE PEDAL DEPRESSED»(ref-189102-S40333966592005090600000) .

Scheme 175

Scheme 176

Scheme 177