Clutch Pressure Test

4R70E/4R75E

Special Testing Procedures





The special tests are designed to aid the technician in diagnosing the hydraulic and mechanical portion of the transmission.

Clutch Pressure Test





1 Electronic pressure control (EPC) readings will vary due to PCM strategy. These values are approximate pressures. Actual clutch apply pressures should be within 0-103 kPa (0-15 psi) of line pressure.

The Clutch Pressure Test will diagnose a low-pressure condition or leakage in a clutch circuit. A difference of 103 kPa (15 psi) or more between the clutch pressure and line pressure will prevent a normal shift.

1. NOTICE: Transmission Fluid Pressure Gauges affect the shift quality of the transmission. Care must be taken not to accelerate or decelerate rapidly. Possible transmission failure can result.

Attach Transmission Fluid Pressure Gauges to the line pressure tap and the appropriate clutch pressure tap according to Band/Clutch Application Chart. Transmission Fluid Pressure Gauges must be accurate enough to distinguish a 103 kPa (15 psi) difference. (If this test is done in conjunction with a control pressure test, Transmission Fluid Pressure Gauges will be attached to all pressure taps.) Have sufficient flexible hose available to read the Transmission Fluid Pressure Gauges in the vehicle.

2. Drive the vehicle. When pressure is applied to the clutch, note the difference between the line Transmission Fluid Pressure Gauge and the corresponding clutch Transmission Fluid Pressure Gauge.

3. If the difference in pressures is less than 103 kPa (15 psi), the corresponding clutch circuit does not have a pressure loss. The Transmission Fluid Pressure Gauge on the line pressure tap and appropriate clutch pressure tap can be switched to confirm that the Transmission Fluid Pressure Gauge calibration differences are not the cause.

4. If the difference is greater than 103 kPa (15 psi), there is a leak in the corresponding clutch pressure circuit. The Transmission Fluid Pressure Gauges on the line pressure tap and clutch pressure tap can be switched to confirm that Transmission Fluid Pressure Gauge calibration differences are not the cause. Carry out the appropriate procedure to correct the clutch leak problem.

5. When the pressure tests are completed, install the pressure tap plugs.
- Tighten to 12 Nm (106 lb-in).