Special Testing Procedures
Special Testing Procedures
The special tests are designed to aid the technician in diagnosing the hydraulic and mechanical portions of the transmission.
Line Pressure Test
WARNING: Block all wheels, set the parking brake and firmly apply the service brake to reduce the risk of vehicle movement during this procedure. Failure to follow these instructions may result in serious personal injury.
NOTICE: Carry out the Line Pressure Test prior to carrying out the Stall Speed Test. If line pressure is low at stall, do not carry out the Stall Speed Test or additional transmission damage will occur. Do not maintain Wide Open Throttle (WOT) in any transmission range for more than 5 seconds or transmission damage may occur.
NOTE: Certain sensor failures may cause high line pressure and Failure Mode Effect Management actions. Make sure that On-Board Diagnostic (OBD) test and electrical repairs have been performed, or test results may be incorrect.
This test verifies the line pressure is within specifications.
1. Connect the Transmission Fluid Pressure Gauge to the line pressure tap.
2. Start the engine and check the line pressures at idle speeds with the transmission in each gear range. Refer to the Pressure Charts to determine if the line pressure is within specification.
3. Check line pressure at Wide Open Throttle (WOT) stall speed with the selector lever in all gear ranges. Slowly press the accelerator pedal to WOT (Wide Open Throttle) and record the pressure reading. After recording the pressure reading, slowly release the accelerator pedal until closed throttle is obtained (idle). Refer to the Line Pressure Chart to determine if the line pressure is within specification.
4. If pressure is not within specification, refer to the Line Pressure Chart for further diagnosis.
5. When line pressure test is complete, install the line pressure tap plug.
- Tighten to 12 Nm (106 lb-in).
Pressure Chart A
NOTE: Actual and commanded pressures vary based on calibration and transmission adaptive strategies. All pressures listed are approximate.
a Commanded pressure as viewed on diagnostic equipment.
Pressure Chart B
NOTE: Actual and commanded pressures vary based on calibration and transmission adaptive strategies. All pressures listed are approximate.
a Commanded pressure as viewed on diagnostic equipment.
Pressure Chart C
NOTE: Actual and commanded pressures vary based on calibration and transmission adaptive strategies. All pressures listed are approximate.
a Commanded pressure as viewed on diagnostic equipment.
b Shift Solenoid Pressure Control D commanded pressure as viewed on diagnostic equipment will be zero. The manual valve controls pressure to the direct clutch in the R detent position.
Pressure Chart D
NOTE: Actual and commanded pressures vary based on calibration and transmission adaptive strategies. All pressures listed are approximate.
a Commanded pressure as viewed on diagnostic equipment.
Line Pressure Diagnostic Chart
Stall Speed Test
WARNING: Block all wheels, set the parking brake and firmly apply the service brake to reduce the risk of vehicle movement during this procedure. Failure to follow these instructions may result in serious personal injury.
NOTICE: Carry out the Line Pressure Test prior to carrying out the Stall Speed Test. If line pressure is low at stall, do not carry out the stall test or additional transmission damage will occur. Do not maintain Wide Open Throttle (WOT) in any gear range for more than 5 seconds.
NOTICE: After testing each of the ranges, move the selector lever into the NEUTRAL position and run the engine at 1,000 rpm for about 15 seconds to allow the torque converter to cool off before continuing onto the next range.
NOTICE: If the engine speed recorded by the scan tool exceeds maximum specified rpm, release the throttle immediately.
NOTE: The stall test should only be carried out with the engine and transmission at normal operating temperatures.
NOTE: Prolonged use may set DTC P0712 or P1783. After carrying out the stall speed test, run On-Board Diagnostic (OBD) test and clear the DTCs.
The stall test checks the operation of the following items:
- Torque converter reactor One-Way Clutch (OWC)
- Forward clutch
- Low One-Way Clutch (OWC)
- Overdrive OWC (One-Way Clutch)
- Engine driveability concerns
1. Connect a scan tool.
2. Press the accelerator pedal to floor WOT (Wide Open Throttle) in each range. Record the rpm reached in each range. Stall speeds should be in the appropriate range.
Stall Speed Chart
Stall Speed Diagnosis Chart
Air Pressure Tests
Air Pressure Test Port Locations
A no-drive condition can exist, even with correct transmission fluid pressure, because of inoperative clutches. Refer to the Clutch, Solenoid Application Chart to determine the appropriate elements. A clutch concern can be located through a series of checks by substituting air pressure for fluid pressure to determine the location of the concern.
Example: When the selector lever is in a forward gear range, a no-drive condition may be caused by an inoperative forward clutch.
1. Drain the transmission fluid and remove the transmission fluid pan.
2. Remove the transmission fluid filter and seal assembly, the solenoid body and solenoid to case gasket.
3. Install the Air Test Plate along with the Transmission Test Plate Screw Set.
- Tighten to 10 Nm (89 lb-in).
4. The inoperative clutches can be located by applying air pressure into the appropriate clutch port. See the Air Pressure Test Port Locations illustration for clutch port locations.
5. Apply 276 kPa (40 psi) of air pressure to the appropriate clutch port. A dull thud may be heard or movement felt when a clutch piston is applied. If the clutch seals or check ball are leaking, a hissing sound may be heard.
6. If the clutches fail to operate during the air check:
- inspect the transmission fluid passages in the case.
- the piston seals are not seated, not installed or are damaged.
- plugged feed holes for clutch apply in the case and/or clutch cylinder.
- damaged piston and/or clutch cylinder.
7. Repair as required and recheck.
8. Reinstall all components.