Circuit Description
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:
| • | 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.
