GM Service Manual Online
For 1990-2009 cars only
Makes 🢒 Cadillac 🢒 2007 🢒 Escalade 🢒 Driver Information and Entertainment 🢒 Cellular, Entertainment, and Navigation 🢒 DTC B2705

Circuit Description

The body control module (BCM) controls the automatic transmission shift lock control solenoid by providing a battery positive voltage to the solenoid. The BCM utilizes a smart driver to control the voltage supply circuit to the automatic transmission shift lock control solenoid. The smart driver monitors the voltage and current flow of the control circuit.

DTC Descriptor

This diagnostic procedure supports the following DTC:

DTC B2705 Gearshift Unlock Circuit

DTC Symptom

DTC Symptom Descriptor

02

Short to Ground

Conditions for Running the DTC
    • The ignition switch is in the ON position.
    • The brake pedal is pressed.
    • The transmission is in the PARK position.

Conditions for Setting the DTC

Sets if there is a short to ground in the automatic transmission shift lock control solenoid control circuit

Action Taken When the DTC Sets

The BCM will not attempt to enable the voltage supply circuit of the automatic transmission shift lock control solenoid until the next key cycle.

Conditions for Clearing the DTC
    • A current DTC B2705 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 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.
    • 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 .

Test Description

The numbers below refer to the step numbers on the diagnostic table.

  1. Listen for an audible click when the automatic transmission shift lock control solenoid operates. Command both the ON and OFF states. Repeat the commands as necessary.

    2.

  2. This step tests for a good ground at the ground circuit of the automatic transmission shift lock control solenoid.

    3.

  3. This step verifies that the BCM is providing battery voltage to the automatic transmission shift lock control solenoid.

    4.

  4. This step tests if battery voltage is constantly being applied to the automatic transmission shift lock control solenoid.

Step

Action

Yes

No

Schematic Reference: Shift Lock Control Schematics

Connector End View Reference: Shift Lock Control Connector End Views

1

Did you perform the Diagnostic System Check - Vehicle?

Go to Step 2

Go to Diagnostic System Check - Vehicle

2

  1. Install a scan tool.
  2. Turn ON the ignition, with the engine OFF.
  3. With a scan tool, command the Shift Lock Solenoid output control ON and OFF.

Does the automatic transmission shift lock control solenoid turn ON and OFF with each command?

Go to Testing for Intermittent Conditions and Poor Connections

Go to Step 3

3

  1. Turn OFF the ignition.
  2. Disconnect the automatic transmission shift lock control solenoid.
  3. 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.

Does the test lamp illuminate?

Go to Step 4

Go to Step 10

4

  1. Turn OFF the ignition.
  2. Connect a test lamp between the shift lock solenoid control circuit and the shift lock solenoid ground circuit at the connector of the shift lock control solenoid.
  3. With a scan tool, command the Shift Lock Solenoid output control ON and OFF several times.

Does the test lamp turn ON and OFF with each command?

Go to Step 8

Go to Step 5

5

Does the test lamp remain illuminated?

Go to Step 6

Go to Step 7

6

Test the control circuit of the automatic transmission shift lock control solenoid for a short to battery voltage. Refer to Circuit Testing and Wiring Repairs .

Did you find and correct the condition?

Go to Step 13

Go to Step 9

7

Test the control circuit of the automatic transmission shift lock control solenoid for an open or short to ground. Refer to Circuit Testing and Wiring Repairs .

Did you find and correct the condition?

Go to Step 13

Go to Step 9

8

Inspect for poor connections at the harness connector of the automatic transmission shift lock control solenoid. Refer to Testing for Intermittent Conditions and Poor Connections and Connector Repairs .

Did you find and correct the condition?

Go to Step 13

Go to Step 11

9

Inspect for poor connections at the harness connector of the body control module (BCM). Refer to Testing for Intermittent Conditions and Poor Connections and Connector Repairs .

Did you find and correct the condition?

Go to Step 13

Go to Step 12

10

Repair the open in the automatic transmission shift lock control ground circuit. Refer to Circuit Testing and Wiring Repairs .

Did you complete the repair?

Go to Step 13

--

11

Replace the automatic transmission shift lock control solenoid. Refer Automatic Transmission Shift Lock Control Actuator Replacement .

Did you complete the replacement?

Go to Step 13

--

12

Replace the BCM. Refer to Control Module References for replacement, setup, and programming.

Did you complete the replacement?

Go to Step 13

--

13
  1. Use the scan tool in order to clear the DTCs.
  2. Operate the vehicle within the Conditions for Running the DTC, as specified in the supporting text.

Does the DTC reset?

Go to Step 2

System OK