P0734

Diagnostic Chart:

Wiring Diagram:

During normal driving modes the PCM/TC adapts line pressure to prevent clutch slip and harsh shifts. If 4th clutch is slipping after pressure is adapted to high line, it is determined that there is no 4th gear. Fourth gear clutch is applied by opening circuit 898 at the PCM.

DTC PARAMETERS
DTC P0734 can be set while driving in 4th (steady state) or during an upshift to 4th when the PCM has detected the following conditions twice per ignition cycle:
- Vehicle speed is above 5 km/h (3 mph).
- Input shaft speed is greater than 224 rpm.
- No input shaft or vehicle speed signal, or noise DTCs.
- High line pressure has been commanded.
- Ratio failure counter is 255 at steady state or shift counter is greater than 100 during a downshift or upshift.

TEST DESCRIPTION
Numbered steps below refer to numbered steps on chart.
1. Check for DTCs P0745, P0708, P0705, P0706, P0746, P0766, P0768, P0749, or P0769. They must be eliminated first as a possible cause of DTC P0734.
2. Check solenoid operation. Use solenoid quick check in 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 4th 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. Check pressure regulator valve operation. Use pressure test in test section at end of DTC charts. Make sure pressure increases in correct increments during pressure test. If pressure is low, repair for pressure condition first.
4. For pressure apply points refer to "Test Section Diagnosis." Apply compressed air, with rubber nozzle on air gun. This step determines if there is an internal problem.
5. As pressure is applied and released, the clutch plates should also apply and release. Observe oil holes in clutch housing. If oil has darkened and contains clutch plate material, the clutches have probably failed.

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: steady state in 4th gear with no slip for 0.4 seconds and engine torque greater than 30 counts for 0.1 seconds.

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 in 4th or the 4th clutch is failed.