P0501-VEHICLE SPEED SENSOR 1 PERFORMANCE

For a complete wiring diagram Refer to Section 8W

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 a multiple ABS wheel speed signals are invalid.

Possible Causes

ABS DTCS PRESENT

TRANSMISSION CONTROL MODULE

Always perform the NAG1 Pre-Diagnostic Troubleshooting procedure before proceeding. (Refer to 21 - TRANSMISSION/TRANSAXLE/AUTOMATIC - NAG1 - STANDARD PROCEDURE)

Diagnostic Test

1.CHECK THE FCM FOR DTCS

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

Yes

Refer to 8-ELECTRICAL - ELECTRONIC CONTROL MODULES - ELECTRICAL DIAGNOSTICS category and perform the appropriate symptom. Perform the diagnostic procedure for U0001-CAN C BUS first if it is present.
Perform NAG1 TRANSMISSION VERIFICATION TEST. (Refer to 21 - TRANSMISSION/TRANSAXLE/AUTOMATIC - NAG1 - STANDARD PROCEDURE)

Go To 2

2.CHECK FOR ABS DTCS

Are there any ABS DTCs present?

Yes

Refer to the ABS category and perform the appropriate symptom.
Perform NAG1 TRANSMISSION VERIFICATION TEST. (Refer to 21 - TRANSMISSION/TRANSAXLE/AUTOMATIC - NAG1 - STANDARD PROCEDURE)

Using the schematics as a guide, check the Transmission Control Module (TCM) terminals for corrosion, damage, or terminal push out. Pay particular attention to all power and ground circuits. If no problems are found, replace the TCM per the Service Information. (Refer to 8 - ELECTRICAL/ELECTRONIC CONTROL MODULES/TRANSMISSION CONTROL MODULE - DESCRIPTION)
Perform NAG1 TRANSMISSION VERIFICATION TEST. (Refer to 21 - TRANSMISSION/TRANSAXLE/AUTOMATIC - NAG1 - STANDARD PROCEDURE)