Service Information

Volt

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 Descriptors

DTC B270A 01: Park Lock Solenoid Control Circuit Short to Voltage

DTC B270A 02: Park Lock Solenoid Control Circuit Short to Ground

DTC B270A 04: Park Lock 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 01, 2	-
Ground	--	B270A 04, 1	--	--
Transmission shift control lever will not move from PARK with the brake pedal applied. Transmission shift control lever will move from PARK without the brake pedal applied.

The body control module controls the transmission shift lock control solenoid actuator by providing a battery positive voltage to the solenoid when the brake pedal is applied. The BCM monitors the voltage and current flow of the control circuit.

Conditions for Running the DTC

•	The ignition switch is in the ON position.

•	The brake pedal is applied.

•	The transmission is in the PARK position.

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

Conditions for Setting the DTC

B270A 01

The body control module detects a short to voltage in the transmission shift lock control solenoid actuator control circuit for 1 second.

B270A 02

The body control module detects a short to ground in the transmission shift lock control solenoid actuator control circuit for 1 second.

B270A 04

The body control module detects an open circuit in the transmission shift lock control solenoid actuator 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 park lock control solenoid until the next power switch cycle.

Conditions for Clearing the DTC

•	A current DTC B270A will clear when the malfunction is no longer present and the power switch is cycled.

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

Reference Information

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

Vehicle in Service Mode.
Verify the scan tool Brake Transmission Shift Interlock Solenoid Actuator Command parameter changes from Inactive to Active when the brake pedal is applied.

⇒	*If the Brake Transmission Shift Interlock Solenoid Actuator Command does not change*

Refer to Stop Lamps Malfunction

⇓	*If the Brake Transmission Shift Interlock Solenoid Actuator Command changes*

Verify the S3 transmission shift lever moves out of the PARK position when the brake pedal is applied.

⇒	*If the S3 transmission shift lever does not move out of the PARK position*

Refer to Circuit/System Testing.

⇓	*If the S3 transmission shift lever does move out of the PARK position*

All OK.

Circuit/System Testing

Vehicle OFF and all vehicle systems OFF, disconnect the harness connector at the S3 transmission shift lever. It may take up to 2 minutes for all vehicle systems to power down.
Test for less than 10 Ω between the ground circuit terminal 2 and ground.

⇒	*If 10 Ω or greater*

2.1.	Vehicle OFF.

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

⇒	If 2 Ω or greater, repair the open/high resistance in the circuit.

⇒	If less than 2 Ω, repair the open/high resistance in the ground connection.

⇓	*If less than 10 Ω*

Vehicle in Service Mode, connect a test lamp between the control circuit terminal 4 and the ground circuit terminal 2.
Verify the test lamp turns ON and OFF when commanding the Brake Transmission Shift Interlock Solenoid Actuator ON and OFF with a scan tool.

⇒	*If the test lamp is always OFF*

4.1.	Vehicle OFF, disconnect the harness connector at the K9 body control module.

4.2.	Test for infinite resistance between the control circuit and ground.

⇒	If less than infinite resistance, repair the short to ground on the circuit.

⇓	If infinite resistance

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

⇒	If 2 Ω or greater, repair the open/high resistance in the circuit.

⇓	If less than 2 Ω

4.4.	Vehicle in Service Mode.

4.5.	Verify a test lamp illuminates between each B+ and ignition circuit terminal at the control module harness connector.

⇒	If the test lamp does not illuminate, repair the circuit or fuse as necessary.

⇒	If the test lamp illuminates at each B+ and ignition circuit, replace the K9 body control module.

⇒	*If the test lamp is always ON*

4.1.	Vehicle OFF, disconnect the harness connector at the K9 body control module, Vehicle in Service Mode.

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

⇒	If 1 V or greater, repair the short to voltage on the circuit.

⇒	If less than 1 V, replace the K9 body control module.

⇓	*If the test lamp turns ON and OFF*

Test or replace the S3 transmission shift lever.

Component Testing

Dynamic Test

Install a 10 A fused jumper wire between the control terminal 4 and 12 V. Momentarily install a jumper wire between the ground terminal 2 and ground.
Verify the solenoid turns on & off/clicks, etc.

⇒	*If the solenoid does not turn on & off/clicks, etc.*

Replace the S3 transmission shift lever.

⇓	*If the solenoid does turn on & off/clicks, etc.*

All OK

Repair Instructions

Perform the Diagnostic Repair Verification after completing the repair.

•	Transmission Control Replacement

•	Control Module References for ECM replacement, programming, and setup.