P0928

P0928-BTSI CONTROL CIRCUIT







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 (SLA) Electronic Shift Module (ESM) receives two brake switch signals. The first signal is a CAN C Bus message sent to the shifter lever assembly. The second signal is a hard wired brake switch signal to the shifter lever assembly from the Wireless Ignition Node (WIN). The CAN C Bus message is the primary brake switch signal and the hard wired 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 on.

- Set Condition:
The Diagnostic Trouble Code (DTC) will set if the high side driver detects a short to ground for 10 seconds.





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

1. ENGINE DTCS PRESENT
1. With the scan tool, read PCM or ECM DTCs.

Are there any Powertrain Control Module (PCM) or Engine Control Module (ECM) brake DTCs present?

Yes

- Testing and Inspection for gas engine applications.

No

- Go To 2

2. CHECK THE (K321) BTSI CONTROL CIRCUIT




1. Turn the ignition off to the lock position.
2. Disconnect the Shifter Lever Assembly harness connector.
3. Ignition on, engine not running.
4. With the scan tool under WIN, actuate the BTSI.

NOTE: Check connectors - Clean/repair as necessary.

5. Using a 12-volt test light connected to ground, check the (K321) BTSI Control circuit.

Does the test light illuminate brightly while cycling on and off on all (K321) BTSI Control circuit?

Yes

- Replace the Shifter Lever Assembly.
- Perform the NAG1 TRANSMISSION VERIFICATION TEST. NAG1 Transmission Verification Test.

No

- Go To 3

3. (K321) BTSI CONTROL CIRCUIT SHORT TO GROUND




1. Turn the ignition off to the lock position.
2. Disconnect the WIN harness connector.

NOTE: Check connectors - Clean/repair as necessary.

3. Measure the resistance between ground and the (K321) BTSI Control circuit.

Is the resistance below 5.0 Ohms?

Yes

- Repair the (K321) BTSI Control circuit for a short to ground.
- Perform the NAG1 TRANSMISSION VERIFICATION TEST. NAG1 Transmission Verification Test.

No

- Go To 4

4. (K321) BTSI CONTROL CIRCUIT OPEN




1. Turn the ignition off to the lock position.

NOTE: Check connectors - Clean/repair as necessary.

2. Measure the resistance of the (K321) BTSI Control circuit between the Shifter Lever Assembly harness connector and the WIN harness connector.

Is the resistance above 5.0 Ohms?

Yes

- Repair the (K321) BTSI Control circuit for an open.
- Perform the NAG1 TRANSMISSION VERIFICATION TEST. NAG1 Transmission Verification Test.

No

- Go To 5

5. (K321) BTSI CONTROL CIRCUIT SHORTED TO VOLTAGE




1. Turn the ignition off to the lock position.
2. Disconnect the Shifter Lever Assembly harness connector.
3. Disconnect the WIN harness connector.
4. Turn the ignition on.

NOTE: Check connectors - Clean/repair as necessary.

5. Measure the voltage between ground and the (K321) BTSI Control circuit.

Is the resistance below 5.0 Ohms?

Yes

- Repair the (K321) BTSI Control circuit for a short to voltage.
- Perform the NAG1 TRANSMISSION VERIFICATION TEST. NAG1 Transmission Verification Test.

No

- Go To 6

6. WIRELESS IGNITION NODE (WIN)
1. Using the schematics as a guide, inspect the wiring and connectors. Repair as necessary. Pay particular attention to all power and ground circuits.

Repair

- Replace the Wireless Ignition Node.
- Perform the NAG1 TRANSMISSION VERIFICATION TEST. NAG1 Transmission Verification Test.