Special Testing Procedures
Special Testing ProceduresThe special tests are designed to aid the technician in diagnosing the hydraulic and mechanical portion of the transmission.
Engine Idle Speed Check
Refer to Computers and Control Systems for diagnosis and testing of the engine idle speed.
Line Pressure Test
CAUTION: Carry out Line Pressure Test prior to carrying out Stall Speed Test. If line pressure is low at stall, do not carry out the Stall Speed Test or further transmission damage will occur. Do not maintain wide open throttle (WOT) in any gear range for more than 5 seconds.
NOTE: Certain sensor failures may cause high PC, FMEM (Failure Mode Effect Management) actions. Be sure that self test and electrical repairs have been carried out, or test results may be incorrect.
NOTE: The line pressure tap is used to verify output pressure from PC A or PC B by turning either one off while verifying the output from the other solenoid. The second pressure tap is used to verify the output from the PC C solenoid.
This test verifies that the line pressure is within specifications.
1. Connect pressure gauge to the line pressure tap.
2. Start engine and check line pressures. Refer to the Line Pressure Chart to determine if line pressure is within specifications.
Line Pressure Chart 3.9L Engine
3. If line pressure is not within specifications, check PC C pressure.
4. Connect Pressure Gauge to PC C pressure tap.
5. Start engine and check PC C pressure. Refer to Line Pressure Diagnosis Chart for specification.
6. If PC C pressure is not within specification, GO to Pinpoint Test D to diagnose PC C operation. If PC C operation is OK, refer to Line Pressure Diagnosis Chart for line pressure concern causes.
Line Pressure Diagnosis Chart
Stall Speed Test
This test checks operation of the following items:
^ torque converter clutch
^ forward clutch
^ low-one way clutch (OWC) assembly
^ engine operation
^ overdrive one-way clutch assembly
WARNING: Apply the parking brake firmly while carrying out each stall test.
CAUTION: Always carry out the Line Pressure Test procedures prior to carrying out the Stall Speed Test. If line pressure is low at stall, do not carry out the Stall Speed Test or further transmission damage will occur.
NOTE: The Stall Speed Test should be carried out with the engine and transmission at normal operating temperatures.
1. Connect tachometer to the engine.
2. CAUTION: After testing each of the following ranges D5, D4, 3, 2, 1 and R. move the transmission range selector lever to N (NEUTRAL) and run the engine at 1,000 rpm for about 15 seconds to allow the torque converter to cool before testing the next range.
CAUTION: Do not maintain wide open throttle (WOT) in any range for more than 5 seconds.
CAUTION: If the engine rpm recorded by the tachometer exceeds maximum specified rpm, release the accelerator pedal immediately. Clutch or band slippage is indicated.
NOTE: Prolonged use of this procedure may set Diagnostic Trouble Code P0712, P1783. After carrying out Stall Speed Test, run OBD Test and clear DTCs from memory.
Press accelerator pedal to floor (WOT) in each range. Record rpm reached in each range. Stall speeds should be as follows:
Stall Speed Chart
3. If stall speeds were too high, refer to the Stall Speed Diagnosis Chart. If stall speeds were too low, first check the engine idle speed. If engine idle is OK, remove torque converter and check the torque converter one-way clutch for slippage.
Stall Speed Diagnosis Chart
Air Pressure Tests
A no-drive or erratic shift condition may be due to inoperative bands and clutches. To diagnose these conditions a series of checks can be made by substituting air pressure for fluid to determine the location of the damaged or obstructed component.
Follow the procedure to determine the location of the inoperative clutch or band by substituting air pressure into the various test plate passages.
NOTE: Use only dry, regulated 276 kPa (40 psi) maximum air pressure.
1. Remove the main control valve body. Refer to Main Control Valve Body.
2. Install the Transmission Test Plate and gasket. Tighten to 10 Nm (89 inch lbs.).
3. NOTE: Do not apply air to the test plate vent hole.
Apply air to the appropriate clutch or servo port (refer to plate layout diagram). Refer to the Air Pressure Test Diagnostic Chart for conditions, possible causes and actions.
4. After the testing is completed, remove the Air Test Plate and Gasket and proceed with any repairs that are needed.
5. After the repairs are completed, install the Main Control Valve Body. Refer to Main Control Valve Body.
Air Pressure Test Diagnostic Chart