Transmission Control Module (TCM) - 8HP45

U1412-IMPLAUSIBLE VEHICLE SPEED SIGNAL RECEIVED

For a complete wiring diagram Refer to the Wiring Information.

Theory of Operation

The purpose of the monitoring is to detect rationality failures of the input speed and output speed sensor signals as well as the wheel speed and engine speed CAN signals. There are three categories of rationalities which include: Multi sensor comparisons of up to three signals (input, output and wheel speed). Monitoring of the gradient of the input speed signal. Double failure monitoring to determine unique failure situations which could require unique limp-in functionality.

- When Monitored:
Continuously when the vehicle is moving and the transmission is in a fixed gear.

- Set Condition:
The failure is detected if the output speed gradient is less than a threshold for a calibrated amount of time.





Always perform the Pre-Diagnostic Troubleshooting procedure before proceeding. 8HP45 Pre-Diagnostic Troubleshooting Procedure

1. CHECK DTC IS CURRENT
1. Turn the ignition ON, Engine Not Running.
2. With the scan tool, select View DTCs.

Is U1412-IMPLAUSIBLE VEHICLE SPEED SIGNAL RECEIVED active at this time?

Yes

- Go To 2

No

- Perform the INTERMITTENT CONDITION diagnostic procedure. Intermittent Condition Test

2. U0001- CAN C BUS CIRCUIT IS ACTIVE
1. Continue reading DTCs.

Is U0001-CAN C BUS CIRCUIT ACTIVE at this time?

Yes

- Perform the appropriate diagnostic procedure. Testing and Inspection Perform the diagnostic procedure for DTC U0001-CAN C BUS first.

No

- Go To 3

3. ABS MODULE IS ACTIVE ON THE CAN C BUS
1. With the scan tool, select ECU View.
2. Verify the ABS Module is active on the bus.

Is the ABS Module active on the bus?

Yes

- Go To 4

No

- Perform the No Response from ABS diagnostic procedure. No Response From ABS (Antilock Brake Module)

4. ACTIVE DTCS IN THE BODY CONTROL MODULE (BCM)
1. With the scan tool, select ECU View and select BCM.
2. With the scan tool, read Active DTCs.

Is the U0002-CAN C BUS OFF PERFORMANCE active in the BCM at this time?

Yes

- Replace the ABS Module. Anti-Lock Brake System Module - Removal.
- Perform the ABS VERIFICATION TEST. ABS Verification Test.

No

- Using the schematics as a guide, check the Transmission Control Module A (TCMA) terminals for corrosion, damage or terminal push out. If no problems are found, replace and program the TCMA. Valve Body - Removal.
- Perform the TRANSMISSION VERIFICATION TEST. Verification Tests.