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Shift Lock Control System: Diagnosis Cadillac STS I facelift

Automatic Trans ~680 words

DIAGNOSTIC CODE INDEX

DTCDescription
DTC B2710B2710 01: Gearshift Unlock Circuit Short to Voltage B2710 02: Gearshift Unlock Circuit Short to Ground

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.

Diagnostic Instructions

  1. Perform the «Diagnostic System Check - Vehicle»(ref-338149-S41903538652009081700000) prior to using this diagnostic procedure.
  2. Review «Strategy Based Diagnosis»(ref-338149-S37154416862009081700000) for an overview of the diagnostic approach.
  3. «Diagnostic Procedure Instructions»(ref-338149-S02595537362009081700000) provides an overview of each diagnostic category.

Diagnostic Fault Information

CircuitShort to GroundOpen/High ResistanceShort to VoltageSignal Performance
Shift Lock Control Solenoid B+B2710 02B2710 02
Shift Lock Control Solenoid ControlB2710 02B2710 02B2710 01

Conditions for Running the DTC

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

Conditions for Setting the DTC

  1. DTC B2710 01 sets when the solenoid control circuit is shorted to voltage.
  2. DTC B2710 02 sets when the solenoid control or supply circuit is open or shorted to ground

Action Taken When the DTC Sets

The RCDLR will not attempt to ground the control circuit of the automatic transmission shift lock solenoid until the next key cycle.

Conditions for Clearing the DTC

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

Circuit/System Testing

  1. Ignition OFF, disconnect the harness connector at the shift lock control solenoid.
  2. Ignition ON, verify a test lamp illuminates between the B+ circuit terminal E and ground. If the test lamp does not illuminate, test the B+ circuit for a short to ground or open/high resistance. If the circuit tests normal, test or replace the shift lock control solenoid.
  3. Connect a test lamp between the B+ circuit terminal E and control circuit terminal K.
  4. Press and release the brake pedal several times. The test lamp should turn ON and OFF as commanded. If the test lamp is always ON, test the control circuit for short to ground. If the circuit tests normal, replace the RCDLR. If the test lamp is always OFF, test the control circuit for an open/high resistance or short to voltage. If the circuit test normal, replace the RCDLR.
  5. If all circuits test normal, test or 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-338151-S01119782592009081700000) .
  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

Transmission Control Lever Malfunction

  1. Perform the «Diagnostic System Check - Vehicle»(ref-338149-S41903538652009081700000) prior to using this diagnostic procedure.
  2. Review «Strategy Based Diagnosis»(ref-338149-S37154416862009081700000) for an overview of the diagnostic approach.
  3. «Diagnostic Procedure Instructions»(ref-338149-S02595537362009081700000) provides an overview of each diagnostic category.
CircuitShort to GroundOpen/High ResistanceShort to VoltageSignal Performance
Shift Lock Control Solenoid B+B2710 02B2710 02
Shift Lock Control Solenoid ControlB2710 02B2710 02B2710 01
  1. Ignition OFF, disconnect the harness connector at the shift lock control solenoid.
  2. Ignition ON, verify a test lamp illuminates between the B+ circuit terminal E and ground. If the test lamp does not illuminate, test the B+ circuit for a short to ground or open/high resistance. If the circuit tests normal, test or replace the shift lock control solenoid.
  3. Connect a test lamp between the B+ circuit terminal E and control circuit terminal K.
  4. Depress and release the brake pedal several times. The test lamp should turn ON and OFF as commanded. If the test lamp is always ON, test the control circuit for short to ground. If the circuit tests normal, replace the RCDLR. If the test lamp is always OFF, test the control circuit for an open/high resistance or short to voltage. If the circuit test normal, replace the RCDLR.
  5. If all circuits test normal, test or replace the shift lock control solenoid.

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