Special Test Procedures
Special Testing Procedures
The special tests are designed to aid the technician in diagnosing the hydraulic and mechanical portions of the transaxle.
Engine Idle Speed Check
Refer to the Powertrain Control/Emissions Diagnosis (PC/ED) manual for diagnosis and testing of the engine idle speed Test KE. Pinpoint Tests
Line Pressure Test
CAUTION: Carry out the Line Pressure Test prior to carrying out the Stall Speed Test. If the line pressure is low at stall, do not carry out the Stall Speed Test or further transaxle damage will occur. Do not maintain wide open throttle in any transaxle range for more than five seconds.
This test verifies that the line pressure is within specification.
1. Connect a pressure gauge to the line pressure tap.
2. Start the engine and check the line pressures see the line pressure chart to determine if the line pressure is within specification.
3. If the line preenure in not within specification check EPC pressure.
4. Connect a pressure gauge to the EPC pressure tap.
5. Start the engine and check the EPC pressure see the line pressure chart for specifications.
6. If the EPC pressure is not within specification GO to Pinpoint Test E Pinpoint Tests to diagnose the EPC operation. If EPC operation is OK see the line pressure diagnosis chart for line pressure concern causes.
Stall Speed Test
WARNING: Apply the parking brake firmly while carrying out each stall test.
CAUTION: Carry out Line Pressure Test prior to carrying out Stall Speed Test. If the line pressure is low at stall, do not carry out Stall Speed Test or further transaxle damage will occur.
The Stall Speed Test checks:
^ torque converter clutch operation and installation.
^ holding ability of the forward clutch.
^ reverse clutch (the low-reverse bands).
^ planetary one-way clutch.
^ engine driveability concerns.
Conduct this test with the engine coolant and transmission fluid at correct levels and at normal operating temperature.
Apply the parking brake firmly for each Stall Speed Test.
1. Find the specified stall rpm for the vehicle see the stall speed chart. Use a grease pencil to mark the rpm on the dial of a tachometer.
2. Connect a tachometer to the engine.
3. NOTE: If the rpm recorded by the tachometer exceeds the maximum limits release the accelerator pedal immediately because clutch or band slippage is indicated.
In each of the following ranges (D), D1, R press the accelerator pedal to the floor and hold it just long enough to let the engine get to wide open throttle (WOT). While making this test do not hold the throttle open for more than 5 seconds at a time.
4. Note: the results in each range.
5. After each range move the selector lever to NEUTRAL and run the engine at 1000 rpm for about 15 seconds to cool the torque converter before making the next test.
6. Use the stall speed diagnosis chart for corrective actions.
7. NOTE: The stall speed in REVERSE will be lower.
Air Pressure Test
If stall speeds were too high see the stall speed diagnosis chart. If stall speeds were too low first check engine idle speed and tune up. If engine is OK remove torque converter and check torque converter clutch for slippage.
A no-drive condition can exist even with correct transmission fluid pressure because of inoperative clutches or bands. An erratic shift can be located through a series of checks by substituting air pressure for fluid pressure to determine the location of the malfunction.
Follow the procedure to determine the location of the inoperative clutch or band by introducing air pressure into the various test plate passages.
NOTE: Use only dry regulated (276 kPa [40 psi] maximum) air pressure.
Apply air to the appropriate passage(s). A dull thud should be felt or heard or movement could be observed when the component applies. There should be no hissing sound when the clutch or band is fully applied.
Cover the vent hole in the test plate with a clean lint-free shop towel to prevent spray when the air is applied. Plugging the vent hole during testing will result in inaccurate results.
1. Drain transmission fluid and remove the transaxle fluid pan. Fluid Pan
2. Remove the main control valve body.
3. Install Transmission Test Plate and Gasket. Tighten bolts to 10-12 Nm (88-106 lb-in).
4. NOTE: Do not apply air to the test plate vent hole.
Apply air to the appropriate clutch port (refer to diagram). A dull thud may be heard or movement felt when the component is applied or released. If clutch seals or check balls are leaking a hissing sound may be heard.
If the servos do not operate disassemble clean and inspect them to locate the source of the concern.
If air pressure applied to the clutch passages fails to operate a clutch or operates clutches simultaneously inspect the fluid passages in the case.
If air pressure applied to the accumulator fails to operate an accumulator remove and inspect case passages and piston.