Transmission Code

P0931-BTSI CONTROL CIRCUIT HIGH - SLA





Theory of Operation
The brake switch signal must be active before the shift lever can be moved out of the park position. The Shifter lever assembly receives two brake switch signals. The first signal is a CAN C Bus message sent to the shift lever assembly. The second signal is a hardwired brake switch signal to the shift lever assembly. The CAN C Bus message is the primary brake switch signal and the hardwired signal serves as the backup brake switch signal. These two brake switch signals are compared against each other to verify proper brake switch operation.
- When Monitored:
Continuously with the ignition key on.
- Set Condition:
The DTC will set if the high side driver detects an open load for 10 seconds.

Possible Causes
- ENGINE BRAKE DTC S PRESENT
- ABS DTC S PRESENT
- (B29) BRAKE SWITCH SIGNAL OPEN
- (B29) BRAKE SWITCH SIGNAL SHORT TO VOLTAGE
- SHIFT LEVER ASSEMBLY

Always perform the NAG1 Pre-Diagnostic Troubleshooting procedure before proceeding. NAG1 Automatic Transmission

Diagnostic Test
1. ENGINE DTC's PRESENT
With the scan tool, read Engine DTC's.
Are there any Engine brake DTC's present?
YES >>Refer to Computers and Control Systems/Testing and Inspection and perform the appropriate diagnostic procedure. Testing and Inspection
Perform NAG1 TRANSMISSION VERIFICATION TEST - VER 1. NAG1 Transmission Verification Test
NO >> Go To 2

2. ABS MODULE DTC's PRESENT
With the scan tool, read ABS Module DTC's.
Are there any ABS DTC's present?
YES >>Refer to BRAKES - ABS ELECTRICAL DIAGNOSTICS and perform the appropriate diagnostic procedure. Testing and Inspection
Perform NAG1 TRANSMISSION VERIFICATION TEST - VER 1. NAG1 Transmission Verification Test
NO >> Go To 3





3. (B29) BRAKE SWITCH SIGNAL OPEN
Turn the ignition off to the lock position.
Disconnect the Shift Lever Assembly harness connector. Disconnect the Stop Lamp Switch harness connector.

NOTE: Check connectors - Clean/repair as necessary.

Measure the resistance of the (B29) Brake Switch Signal circuit between the Shift Lever Assembly harness connector and the Stop Lamp Switch.
Is the resistance above 5.0 ohms?
YES >>Repair the (B29) Brake Switch Signal for an open.
Perform NAG1 TRANSMISSION VERIFICATION TEST VER 1. NAG1 Transmission Verification Test
NO >>Go To 4





4. (B29) BRAKE SWITCH SIGNAL SHORT TO VOLTAGE
Turn the ignition off to the lock position. Disconnect the Shift Lever Assembly harness connector.

NOTE: Check connectors - Clean/repair as necessary.

Turn the ignition on.
Measure the voltage of the (B29) Brake Switch Signal circuit.
Is the voltage above 0.5 volts?
YES >>Repair the (B29) Brake Switch Signal for a short to voltage. Perform NAG1 TRANSMISSION VERIFICATION TEST VER 1. NAG1 Transmission Verification Test
NO >>Replace the Shift Lever Assembly.
Perform NAG1 TRANSMISSION VERIFICATION TEST - VER 1. NAG1 Transmission Verification Test