NAG1 Shifter - ESM (Column Shift)

P0931-BTSI CONTROL CIRCUIT HIGH - ESM (COLUMN SHIFT)





For a complete wiring diagram Refer to Diagrams/Electrical Electrical Diagrams


Theory of Operation


The brake switch signal must be active before the shift lever can be moved out of the park position. The Electronic Shift Module (ESM) receives two brake switch signals. The first signal is a CAN C BUS message and the second signal is a hard wired brake switch signal to the shifter lever assembly. 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 key on.

- Set Condition:

The DTC will set if the high side driver detects an open load for 10 seconds.







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



Diagnostic Test


1. ENGINE DTCs PRESENT

With the scan tool, read Engine DTCs.

Are there any Engine brake DTCs present?

Yes


- Perform NAG1 TRANSMISSION VERIFICATION TEST. NAG1 Transmission Verification Test

No

- Go To 2



2. ABS MODULE DTCs PRESENT

With the scan tool, read ABS Module DTCs.

Are there any ABS DTCs present?

Yes

- Refer to Brakes and Traction Control/Testing and Inspection and perform the appropriate symptom(s).
- Perform NAG1 TRANSMISSION VERIFICATION TEST. NAG1 Transmission Verification Test

No

- Go To 3



3. (B29) BRAKE SWITCH SIGNAL OPEN





Turn the ignition off to the lock position.

Disconnect the ESM harness connector.

Disconnect the Stop Lamp Switch harness connector.

Measure the resistance of the (B29) Brake Switch Signal circuit between the ESM harness connector and the Stop Lamp Switch harness connector.

Is the resistance above 5.0 ohms?

Yes

- Repair the (B29) Brake Switch Signal for an open.
- Perform NAG1 TRANSMISSION VERIFICATION TEST. NAG1 Transmission Verification Test

No

- Go To 4



4. (B29) BRAKE SWITCH SIGNAL SHORT TO VOLTAGE





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. NAG1 Transmission Verification Test

No

- Using the schematics as a guide, check the Electronic Shift Module (ESM) terminals for corrosion, damage, or terminal push out. Pay particular attention to all power and ground circuits. If no problems are found, replace the ESM (Steering Column).
- Perform NAG1 TRANSMISSION VERIFICATION TEST. NAG1 Transmission Verification Test