P1DD1

P1DD1-INPUT/TURBINE SPEED SENSOR 1 GRADIENT FAULT

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 input 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, CLEAR transmission DTCs.
3. Raise the vehicle on the hoist.
4. Start the engine.
5. With the scan tool, monitor the Input Speed Sensor RPM.
6. Firmly apply the brake pedal and place the gear selector in Drive.

WARNING: To avoid personal injury or death, keep hands and feet clear of rotating wheels.

7. Release the brakes and raise the engine rpm to allow the transmission to perform a 2-3 and 3-4 upshift.

Did the Input Speed Sensor display an rpm above 7,700?

Yes

- Go To 2

No

- Using the schematics as a guide, check the Transmission Control Module A (TCMA) terminals 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 TCMA. Valve Body - Removal.
- Perform the TRANSMISSION VERIFICATION TEST. Verification Tests.

2. INTERNAL TRANSMISSION
1. This DTC is an indication of a internal transmission failure.
2. Remove the Transmission Oil Pan and inspect for excessive debris such as clutch friction material or metal contamination.

Is there any indication of an internal transmission failure?

Yes

- Repair internal transmission as necessary. Verify the surface of the P4 annulus drum is not damaged. 8HP45 Automatic Transmission - Disassembly.
- Perform the TRANSMISSION VERIFICATION TEST. Verification Tests.

No

- Using the schematics as a guide, check the TCMA terminals 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 TCMA. Valve Body - Removal.
- Perform the TRANSMISSION VERIFICATION TEST. Verification Tests.