DTC P0783

Circuit Description

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When a gear is commanded ON, the vehicle speed to input shaft speed ratio is monitored to assure the correct gear ratio. Shift solenoid 4 performance indicates that another gear was commanded but the actual ratio driving the vehicle is equal to 4th gear. This is a calculated value, input shaft speed/vehicle speed equals greater ratio. Fourth gear clutch is turned OFF by grounding circuit 898 at the PCM.

Conditions for Setting the DTC

DTC P0783 is set when the PCM has detected the following conditions for more than 3 seconds, twice per ignition cycle.

First gear is commanded by the PCM.
Engine under load and load value is greater than 200.
The speed ratio across the torque converter, engine speed versus input shaft speed, is less than 180. A speed ratio of 255 would be TCC on.
No noise or input shaft or vehicle speed signals.
Vehicle speed is greater than 5 km/h (3 mph).
Input shaft speed is greater than 224 RPM.
Input shaft speed to vehicle speed ration equals 4th gear for more than 200 milliseconds.

Test Description

Numbered steps below refer to numbered steps on the chart.

Check for DTCs P0766, P0768, or P0769. They must be eliminated first as a possible cause of DTC P0783.

Important

To check the solenoid operation, command the solenoid quick test using the scan tool.

Check the solenoid operation. Use the solenoid quick check in the test section located at the end of the DTC charts. The solenoid quick test will PWM the solenoids at a set rate. Listen and compare the noise of the 4th gear solenoid to that of the other solenoids. The noise should be similar.
The problem could be a mechanical failure. This step begins the internal diagnosis. The air check procedure is in the Test Section Diagnosis at the end of the DTC charts.
As air pressure is applied and released, the clutch plates should also apply and release. If the clutch plates are moving normally, the problem is probably in the valvebody. If clutches are not moving correctly, the problem is in the end cover or an internal transaxle problem exists.

Repair Verification

Monitor the DTC menu Code Status for Pass Since Code Clear and Pass This Ignition Cycle. When both have passed, the repair is verified.

Criteria for pass:

The engine is running.
Power is present at the solenoids and no active faults exist for this solenoid.

Diagnostic Aids

This code may set or intermittent 4th gear starts may be caused by a poor electrical connection at either the PCM, solenoid connector plate, or UHJB terminals. Wiggling the connectors while performing a solenoid quick test may help isolate the problem area.

This DTC will probably be accompanied by DTC P0732, DTC P0733, and DTC P0741.