Transmission Control Module (TCM) - NAG1

P0501-VEHICLE SPEED SENSOR 1 PERFORMANCE

For a complete wiring diagram, refer to the Wiring Information.

Theory of Operation

The Transmission Control Module (TCM) receives information from the Engine, Anti-lock Brake System, and the Electronic Gear Shift control modules over the CAN C bus. The CAN C bus is a high speed communication bus that allows real time control capability between various controllers. Most messages are sent every 20 msec, this means critical information can be shared between multiple controllers almost instantaneously. The CAN C bus is a two wire bus with a CAN (+) and a CAN (-) circuit. To reduce the potential of radio and other electrical noise interference, the CAN Bus circuit wiring is manufactured using a twisted pair configuration within the electrical wiring harness.

- When Monitored:
Continuously with the ignition on.

- Set Condition:
The DTC will set if multiple ABS wheel speed signals are invalid.





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

1. CHECK THE TIPM FOR DTCS
1. With the scan tool, check for TIPM DTCs.

Does the TIPM report the DTC U0001-CAN C BUS DTC or U0121-LOST COMMUNICATION WITH ANTI-LOCK BRAKE MODULE?

Yes

- Testing and Inspection Perform the appropriate diagnostic procedure. Perform the diagnostic procedure for DTC U0001-CAN C BUS first.
- Perform NAG1 TRANSMISSION VERIFICATION TEST. NAG1 Transmission Verification Test.

No

- Go To 2

2. CHECK FOR ABS DTCS
1. With the scan tool, check for ABS DTCs.

Are there any ABS DTCs present?

Yes

- Testing and Inspection Perform the appropriate test.
- Perform NAG1 TRANSMISSION VERIFICATION TEST. NAG1 Transmission Verification Test.

No

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