DTC B270A

/ 9-4x / 2011 / 4. Transmission / Automatic Transmission (6T70/6T75) / Fault diagnosis, diagnostic trouble codes / DTC B270A

Diagnostic Instructions

•	Perform the Diagnostic System Check - Vehicle prior to using this diagnostic procedure.

•	Review Strategy Based Diagnosis for an overview of the diagnostic approach.

•	Diagnostic Procedure Instructions provides an overview of each diagnostic category.

DTC Descriptor

DTC B270A 02

Shift Lock control solenoid control circuit short to ground

DTC B270A 04

Shift Lock control solenoid control circuit open

Diagnostic Fault Information

Circuit	Short to Ground	Open/High Resistance	Short to Voltage	Signal Performance
Control	B270A 02, 1	B270A 04, 1	B270A 04, 2	-
Ground	-	B270A 04, 1	-	-

Circuit/System Description

Body control module (BCM) controls the automatic transmission's control solenoid for Shift Lock by feeding the control solenoid with positive battery voltage when the brake pedal is pressed down. BCM monitors the control circuit's flow of voltage and current.

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.

•	The DTC runs continuously once the above conditions are met.

Conditions for Setting the DTC

B270A 02

The body control module detects a short to ground in the automatic transmission Shift Lock control solenoid control circuit for 1 second.

B270A 04

The body control module detects an open or short to voltage in the automatic transmission Shift Lock control solenoid control circuit for 1 second.

Action Taken When the DTC Sets

The body control module 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 B270A will clear when the malfunction is no longer present and the ignition switch is cycled.

•	A history DTC will clear after 100 ignition cycles with no current DTC active during the 100 ignition cycles.

Reference Information

Schematic Reference

Shift Lock Control Schematics

Connector End View Reference

Component Connector End Views

Description and Operation

Automatic Transmission Shift Lock Control Description and Operation

Electrical Information Reference

•	Circuit Testing

•	Connector Repairs

•	Testing for Intermittent Conditions and Poor Connections

•	Wiring Repairs

Scan Tool Reference

Control Module References for scan tool information

Circuit/System Verification

1.	Ignition ON.

2.	Verify that the scan tool's Brake Transmission Shift Interlock Solenoid Actuator Command parameter changes from Inactive to Active while pressing and releasing the brake pedal.

3.	If the parameter does not change: See Brake light, malfunction

4.	If the parameter changes from Inactive to Active

5.	Verify that the S3 gear select lever moves from PARK when pressing down the brake pedal.

6.	If the S3 gear select lever does not move from PARK See Test of circuit/system below.

7.	If the S3 gear select lever does move from PARK Everything is OK.

Circuit/System Testing

1.	Ignition OFF and all vehicle systems OFF, disconnect the cable connection on the S3 gear select lever. It can take up to 2 minutes for all vehicle systems to be deenergized.

2.	Test for less than 10 Ω between the ground circuit pin 2 and ground.

3.	If the value is 10 Ω or higher:

3.1.

Ignition OFF.

3.2.

Test for less than 2 Ω in the ground circuit end to end.

3.3.

If the value is 2 Ω or higher, rectify the open circuit/high resistance in the circuit.

3.4.

If the value is less than 2 Ω, rectify the open/high resistance at the connection to ground.

4.	If the value is less than 10 Ω

5.	Ignition ON, connect a test lamp between the control circuit pin 4 and the ground circuit pin 2.

6.	Verify that the test lamp comes on and goes out when you switch between Brake transmission shift interlock solenoid actuator Active and Inactive with the scan tool.

7.	If the lamp is not lit constantly:

7.1.

Ignition OFF, disconnect the cable connection from the body's electronic unit K9.

7.2.

Test for infinite resistance between the control circuit and ground.

7.3.

If the value is less than infinite resistance, rectify the short circuit to ground in the circuit.

7.4.

If the resistance is infinite:

7.5.

Test for less than 2 Ω in the control circuit end to end.

7.6.

If the value is 2 Ω or higher, rectify the open circuit/high resistance in the circuit.

7.7.

If the value is less than 2 Ω

7.8.

Ignition ON.

7.9.

Verify that a test lamp lights between each B+ and the ignition circuit pin on the control module's connector.

7.10.

If the test lamp does not light, rectify the circuit/fuse.

7.11.

If the test lamp lights between each B+ and the ignition circuit, replace K9 the body's electronic unit.

8.	If the test lamp is constantly lit:

8.1.

Ignition OFF, disconnect the cable connection from the body's electronic unit K9, ignition ON.

8.2.

Test for less than 1 V between the control circuit and ground.

8.3.

If the value is 1 V or higher, rectify the short circuit to voltage on the circuit.

8.4.

If the value is lower than 1 V, replace K9 body's electronic unit.

9.	If the test lamp lights and goes out

10.	Test or replace S3 gear select lever.

Component test

Dynamic test

1.	Install a 10 A fuse-protected bridge cable between the control circuit's pin 4 and 12 V. Temporarily install a bridge cable between the ground pin 2 and ground.

2.	Verify that the solenoid valve switches ON and OFF, emits a click sound, etc.

3.	If the solenoid valve does not switch ON and OFF, emits a click sound, etc. Replace S3 gear select lever.

4.	If the solenoid valve switches ON and OFF, emits a click sound, etc.

5.	Everything is OK

Repair Instructions

Perform the Diagnostic Repair Verification after completing the repair.

•	Transmission Control Replacement

•	Control Module References for BCM replacement, setup, and programming

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