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Shift Lock Control System: Diagnosis Saturn Sky I

Automatic Trans ~597 words

DIAGNOSTIC CODE INDEX

DTCDescription
DTC B2705Gearshift Unlock Circuit Short to Ground or Battery, or Open

DIAGNOSTIC CODE INDEX

Diagnostic Starting Point - Automatic Transmission Shift Lock Control

Begin the system diagnosis with the Diagnostic System Check - Vehicle . The Diagnostic System Check will provide the following information

  1. The identification of the control modules which command the system
  2. The ability of the control modules 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.

Scan Tool Output Controls

Scan Tool Output ControlAdditional Menu Selection(s)Description
Brake to Shift ControlSpecial Functions-Output ControlCommand supplies battery voltage to the A/T shift lock control circuit ON or OFF.

Body Control Module (BCM)

Scan Tool Data List

Scan Tool ParameterData ListUnits DisplayedTypical Data Value
Operating Conditions: Ignition ON, with the Engine OFF. Transmission Shift Lever in the PARK Position.
Battery Voltage SignalBCM, Power Mode0-15 volts12 volts
Brake Lamp Cmd.BCM, Chassis DataON/OFFON
BTSI SolenoidBCM, Chassis DataOn/OffOff

Body Control Module (BCM)

Scan Tool ParameterData ListUnits DisplayedTypical Data Value
Operating Conditions: Ignition ON, with the Engine OFF. Transmission Shift Lever in the PARK Position.
Ignition 1 SignalECM, Engine DataVolts12 V

Engine Control Module (ECM)/Powertrain Control Module)

Diagnostic Instructions

  1. Perform the «Diagnostic System Check - Vehicle»(ref-269795-S23164669932007110200000) prior to using this diagnostic procedure.
  2. Review for an overview of the diagnostic approach.
  3. provides an overview of each diagnostic category.

Diagnostic Fault Information

CircuitShort to GroundOpen/High ResistanceShort to VoltageSignal Performance
Shift Lock Control Solenoid Voltage Supply CircuitB2705 05B2705 05
Shift Lock Control Solenoid Ground CircuitB2705 02

DTC B2705

Scan Tool Parameter Data

  1. «Scan Tool Output Controls»(ref-269820-S07039801792007110200000)
  2. «Scan Tool Data List»(ref-269820-S14968295232007110200000)

Conditions for Running the DTC

  1. The ignition switch is in the ON position.
  2. The brake pedal is pressed.
  3. The transmission is in the PARK position.

Conditions for Setting the DTC

The engine control module (ECM)/powertrain control module (PCM) detects a system voltage below 10 volts for 5 seconds.

Action Taken When the DTC Sets

  1. The BCM will not attempt to enable the voltage supply circuit of the automatic transmission shift lock control solenoid until the next key cycle.
  2. The BCM stores DTC B2705 in memory.

Conditions for Clearing the DTC

  1. A current DTC B2705 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.

Diagnostic Aids

  1. if the automatic transmission shift lock control circuit is shorted to ground, the automatic transmission shift lock control solenoid will be inoperative. The vehicle will shift out of PARK without pressing the brake pedal.
  2. Perform the tests while wiggling the wires and connectors. This may often cause an intermittent malfunction to appear.

Circuit/System Testing

  1. Ignition OFF, disconnect the harness connector at the shift lock control solenoid.
  2. Ignition OFF, test for less than 1.0 ohm of resistance between the ground circuit terminal 3 and ground. If greater than the specified range, test the ground circuit for an open. If the circuit tests normal, replace the shift lock control solenoid.
  3. Ignition ON and the engine OFF, command the Brake To Shift Control output control ON and OFF. The automatic transmission shift lock control solenoid should turn ON and OFF and allow the transmission to be shifted out of the PARK position. If unable to shift out of PARK, test for an open or short to ground in the control circuit.
  4. Ignition ON and the engine OFF, connect a test lamp between the shift lock control solenoid ground circuit at the connector of the shift lock control solenoid and battery positive voltage. With the brake pedal applied, the test lamp should illuminate. If test lamp does not illuminate, replace the shift lock control solenoid.

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»(ref-269796-S31812107652007110200000) .
  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-269820-S36242093342007110200000)
  2. «Shift Lever Can Be Moved without Brake Pedal Depressed»(ref-269820-S08465973722007110200000)

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