P0781

Diagnostic Chart:

Wiring Diagram:

When a gear is commanded On, the vehicle speed to input shaft speed ratio is monitored to assure the correct gear ratio. Shift solenoid 2 - performance indicates that 1st gear was commanded On but the actual ratio driving the vehicle is equal to 2nd gear. This is a calculated value ISS rpm/VSS rpm speed (input shaft speed sensor/vehicle speed sensor = gear ratio). Second gear clutch is turned Off by grounding circuit 1222 at the PCM.

DTC PARAMETERS

DTC P0781 is set when the PCM has seen the following conditions for more than three seconds twice per ignition cycle:

^ 1st gear commanded by PCM.

^ No noise detected on input shaft or vehicle speed signals.

^ Vehicle speed greater than 5 km/h (3 mph).

^ Input shaft speed greater than 224 rpm.

^ Speed ratio across the torque converter, engine speed versus input speed, less than 180. A speed ratio of 255 would be TCC on.

^ PCM calculated engine load value is greater than 200.

^ The ratio of input shaft speed to vehicle speed equals that of 2nd gear.

TEST DESCRIPTION

1. Check for DTCs P0756, P0758, P0740 or P0759. They must be eliminated first as a possible cause of DTC P0781.

2. Check solenoid operation. Use solenoid quick check in test section. Listen and compare noise of 2nd gear solenoid to that of other solenoids. The noise of all should be similar.

IMPORTANT: To check solenoid operation, command solenoid quick test using the Scan tool.

3. Perform 2nd clutch air check. For pressure apply points refer to "Test Section Diagnosis." Apply compressed air with rubber nozzle on air gun. Problem could be a mechanical failure. This step begins internal diagnosis.

4. Cross leaks to and from 2nd clutch circuit can cause 2nd clutch to be on at all times. If DTC P0781 is present and there is no reverse, check end cover input hub seals.

5. As air pressure is applied and released, the clutch plates should also apply and release. If clutch plates are moving normally and no other leaks detected, the problem is probably in the valve body. If clutches are not moving correctly, the problem is in the end cover or an internal clutch assembly problem.

REPAIR VERIFICATION

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

Criteria for pass:

^ Engine running

^ Power present at solenoids and no active faults exist for this solenoid.

DIAGNOSTIC AIDS

^ When the PCM detects a fault in the circuit (open, ground, short), the PCM will open the circuit internally to protect the circuit.

^ Could be a hot or cold only condition. If condition is intermittent, try to reproduce conditions in MALF table to reset the DTC.

^ Problem could be internal. Possible hydraulic leak, seals, gaskets, porosity, etc.

^ This DTC may set or intermittent 2nd gear starts may be caused by a poor electrical connection at either the PCM, solenoid connector plate or UHJB terminals. Wiggling connectors while performing a solenoid quick test may help isolate the problem area.