MECHANICAL SYSTEM TEST [5R55S]

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Mechanical System Test Preparation

1.  Engage the parking brake and use wheel chocks at the front and rear of the wheels.

2.  Inspect the engine coolant level. (See COOLING SYSTEM SERVICE WARNINGS [WL-C, WE-C].) (See ENGINE COOLANT LEVEL INSPECTION [WL-C, WE-C].)

3.  Inspect the engine oil level. (See ENGINE OIL LEVEL INSPECTION [WL-C, WE-C].)

4.  Inspect the ATF level. (See AUTOMATIC TRANSMISSION FLUID (ATF) INSPECTION [5R55S].)

5.  Inspect the idle speed. (See ENGINE TUNE-UP [WL-C, WE-C].)

Line Pressure Test (Pressure Control A, Pressure Control B)

Warning

•  Removing the plug when the ATF is hot is dangerous. Hot ATF can discharge from the opening and cause severe burns. Before removing the line pressure tap, allow the AT and ATF to cool.

Caution

•  Perform the line pressure test before performing the stall test. If the line pressure is low at stall speed, do not perform the stall test or further transmission damage will occur.

•  Do not maintain WOT in any gear position for more than 5 s.

Note

•  Certain sensor failures may cause high pressure control, Failure Mode Effect Management (FMEM) actions. Be sure that the self-test and electrical repairs have been carried out or test results may be incorrect.

•  The line pressure tap is used to verify output pressure from pressure control A or pressure control B. Use PC PIDs and take note which solenoid, pressure control A or pressure control B, is commanded higher. Use the higher commanded PC x value when referencing the Line Pressure Charts A and B. The second pressure tap is used to verify the output from the pressure control solenoid C.

Pressure control A, pressure control B

1.  Remove the line pressure tap.

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2.  Connect the pressure gauge (SST: 49 0378 400C) to the line pressure tap.

3.  Connect the diagnostic scan tool and monitor the PC A and PC B PIDs. Note which PID is commanded higher. Use the higher commanded PC x value when referencing the Line Pressure Charts A and B.

4.  Start the engine and check the line pressure reading from the gauge installed in Step 1. Refer to the Line Pressure Chart for the correct shift lever position.

•  If the line pressure is not within ranges given in Line Charts A and B, refer to Line Pressure Diagnosis Chart in this section for line pressure concern causes.

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5.  Install the line pressure tap.

6.  Go to the Pressure Control C Pressure Test in this section.

Pressure Control C

1.  If not previously connected, install the scan tool.

2.  Remove the line pressure tap.

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3.  Connect the pressure gauge (SST: 49 0378 400C) to the line pressure tap.

4.  Using the diagnostic scan tool, monitor the PC C PID and note the commanded pressure.

5.  Start the engine and check the PC C pressure.

•   If the gauge reading does not match within ±103 kPa {1.05 kgf/cm², 15 psi} of the PID value displayed for the PC C, inspect the pressure control solenoid C. (See SOLENOID VALVE INSPECTION [5R55S].)

•  If pressure control solenoid C operation is normal, refer to the Line Pressure Diagnosis Chart in this section for line pressure concern causes.

Line pressure (pressure control C)

6.  Install the line pressure tap.

Line pressure diagnosis chart

Test Results	Possible Source
High at Idle—All Ranges	•  Wiring harnesses •  PC C boost valve •  Pressure control solenoid C •  Main regulator valve
Low at Idle—All Ranges	•  Low fluid level •  Fluid inlet filter/seal •  Control valve body •  Cross leaks •  Gaskets •  Pump •  Separator plate
Low—All Forward Ranges	•  Forward Clutch •  Main Control •  Overdrive brake servo •  Intermediate brake servo
Low in P position Only	•  Control valve body
Low in R position Only	•  Separator plate •  Reverse servo piston, cover seal •  Reverse clutch •  Overdrive brake servo •  Intermediate brake servo •  Control valve body •  Forward clutch
Low in N position Only	•  Control valve body •  Overdrive brake servo •  Intermediate brake servo
Low in D range	•  Forward clutch •  Overdrive brake servo •  Intermediate brake servo •  Control valve body
Low in D range Only (O/D OFF mode)	•  Forward clutch •  Overdrive brake servo •  Intermediate brake servo •  Control valve body
Low in 1 range	•  Forward clutch •  Control valve body
Low in 2 range	•  Intermediate brake servo •  Overdrive brake servo •  Forward clutch
Low in 3 range	•  Intermediate brake servo •  Overdrive brake servo •  Forward clutch

Stall Speed Test

Warning

•  Apply the parking brake firmly while performing each stall test. Failure to set the brakes can result in death or severe injury.

Caution

•  Perform the line pressure test before performing the stall test. If the line pressure is low at stall speed, do not perform the stall test or further transmission damage will occur.

•  The stall test should only be performed with the engine and transmission at normal operating temperature.

Note

•  The stall speed test inspects the operation of the following:

―  Torque converter clutch

―  Forward clutch

―  Low/reverse one-way clutch

―  Low one-way clutch component

―  Engine driveability concerns

―  Overdrive one-way clutch component

1.  Connect a tachometer to the engine.

Caution

•  Do not maintain WOT in any shift position for more than 5 s.

•  If the engine rpm recorded by the tachometer exceeds the maximum specified rpm, release the accelerator pedal immediately. Otherwise, clutch or band slippage could occur.

Note

•  Prolonged use of this procedure may set DTC P0712 or P1783. After carrying out the Stall Speed Test, run the OBD Test and clear DTCs from the memory.

2.  Depress the accelerator pedal to the floor (WOT) in each shift position. Record the rpm reached in each shift position.

3.  After testing the D, 3, 2, 1 range and R position, shift the selector lever to the N position and run the engine at 1,000 rpm for 15 s to allow the torque converter to cool before testing the next gear position.

•  If the stall speed is too high, refer to the stall speed diagnosis chart.

Stall speed diagnosis chart

4.  If the stall speed is too low, inspect the idle speed.

•  If the idle speed is normal, remove the torque converter and inspect the torque converter one-way clutch for slippage.