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How to Perform Trouble Diagnosis for
Quick and Accurate Repair " .
NOTE:
Stall revolution is too high in “D”, “2”, or “1” position:
• Slippage occurs in 1st gear but not in 2nd and 3rd gears. ..... Low one-way clutch slippage
• Slippage occurs in the following gears:
1st through 3rd gears in “D” position and engine brake f unctions with OD OFF. (OD OFF indicator lamp is
on.)
1st and 2nd gears in “2” position and engine brake functions with accelerator pedal released (fully closed
throttle)...... Forwar d clutch or forward one-way clutch slippage
Stall revolution is too high in “R” position:
• Engine brake does not function in “1” posit ion. ..... Low & reverse brake slippage
• Engine brake functions in “1” position. ..... Reverse clutch slippage
Stall revolution with in specifications:
• Vehicle does not achieve speed of more than 80 km/h ( 50 MPH). ..... One-way clutch seizure in torque con-
verter housing
CAUTION:
Be careful because automatic flui d temperature increases abnormally:
• Slippage occurs in 3rd and 4th gears in “D” position. ..... High clutch slippage
• Slippage occurs in 2nd and 4th gears in “D” position. ..... Brake band slippage
• Engine brake does not function in 2nd and 3rd gears in “D” position, 2nd gear in “2” position, and 1st gear in “1” position with OD OFF. (OD OFF indicator lamp is on.) ..... Overrun clutch slippage
Stall revolution less than specifications:
• Poor acceleration during starts. ..... One-way clutch seizure in torque converter Stall revolution:
AT-373, " Stall Speed "
SAT771B
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AT
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LINE PRESSURE TEST
Line Pressure Test Ports
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AT-54< SERVICE INFORMATION >
TROUBLE DIAGNOSIS
Location of line pressure test ports are shown in the figure.
• Always replace pressure plugs as they are self-sealing bolts.
Line Pressure Test Procedure
1. Check ATF and engine oil levels. If necessary, add ATF or engine oil.
2. Drive vehicle for approx. 10 minutes or until engine oil and ATF reach operating temperature.
3. Install oil pressure gauge to corresponding line pressure test port.
4. Set parking brake and block wheels.
5. Start engine and measure line pressure at idle and stall speed. CAUTION:
• Keep the brake pedal pressed all the way down during
measurement.
• When measuring the line pressure at the stall speed, refer to "STALL TEST". SCIA7187E
ATF operating temperature: 50 - 80
°C (122 -176 °F) SAT647B
SCIA6528J
SAT513G
SAT493G
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AT
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Line Pressure
Judgement of Line Pressure Test
Road Test INFOID:0000000004305320
DESCRIPTION • The purpose of the test is to det ermine overall performance of A/T
and analyze causes of malfunctions.
• The road test consists of the following three parts:
1. Check before engine is started. Refer to AT-56 .
2. Check at idle. Refer to AT-56 .
3. Cruise test • Inspection all the item from Part 1 to Part 3. Refer to AT-58 ,
AT-61 and
AT-62 .
Engine speed
Line pressure [kPa (kg/cm
2
, psi)]
D, 2nd and 1st positions R position
Idle speed AT-373, " Line Pressure "
Stall speed
Judgement Suspected parts
At idle Line pressure is low in all positions. • Oil pump wear
• Control piston damage
• Pressure regulator valve or plug sticking
• Spring for pressure regulator valve damaged
• Fluid pressure leakage between oil strainer and pressure regulator valve
• Clogged strainer
Line pressure is low in particular posi-
tion. • Fluid pressure leakage between manual valve and particular clutch
• For example, line pressure is: − Low in “R” and “1 ” positions, but
− Normal in “D”, and “2” positions.
Therefore, fluid leakage exists at or around low and reverse brake circuit.
Refer to AT-22, " Shift Mechanism " .
Line pressure is high. • Accelerator pedal position signal malfunction • A/T fluid temperature sensor damaged
• Line pressure solenoid valve sticking
• Short circuit of line pressure solenoid valve circuit
• Pressure modifier valve sticking
• Pressure regulator valve or plug sticking
• Open in dropping resistor circuit
At stall
speed Line pressure is low. • Accelerator pedal position signal malfunction
• Line pressure solenoid valve sticking
• Short circuit of line pressure solenoid valve circuit
• Pressure regulator valve or plug sticking
• Pressure modifier valve sticking
• Pilot valve sticking
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). Per-
form a diagnosis of the NG items after the completion of all the
road tests.
Check Before Engine Is Started INFOID:0000000004305321YES >> 1. Turn ignition switch OFF.
2. Perform self-diagnosis and note NG items.Refer to AT-79, " CONSULT-III Function (TRANS-
MISSION) " ,
AT-83, " Diagnosis Procedure without
CONSULT-III " .
3. Go to AT-56, " Check at Idle " .
NO >> Stop “Road Test”. Go to AT-181, " OD OFF Indicator
Lamp Does Not Come On " .
Check at Idle INFOID:0000000004305322YES >> GO TO 2.
NO >> • Stop “Road Test”. Mark the box on the “Diagnostic
Worksheet Chart”.
• Go to AT-183, " Engine Cannot Be Started in "P" and
"N" Position " . SAT772B
SAT769B
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AT
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2. Move selector lever to “R”, “D”, “2” or “1” position.
3. Turn ignition switch to “START” position.
Is engine started? YES >> • Stop “Road Test”. Mark the box on the “Diagnostic
Worksheet Chart”.
• Go to AT-183, " Engine Cannot Be Started in "P" and
"N" Position " .
• Continue “Road Test”.
NO >> GO TO 3. YES >> • Mark the box on the “D
iagnostic Worksheet Chart”.
• Go to AT-184, " In "P" Position, Vehicle Moves Forward
or Backward When Pushed " .
• Continue “Road Test”.
NO >> GO TO 4. YES >> • Mark the box on the “D
iagnostic Worksheet Chart”.
• Go to AT-184, " In "N" Position, Vehicle Moves " .
• Continue “Road Test”.
NO >> GO TO 5. SAT768B
SAT796A
SAT771B
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“ N ” to “ R ” position?
YES >> • Mark the box on the “Diagnostic Worksheet Chart”.
• Go to AT-185, " Large Shock "N" " .
• Continue “Road Test”.
NO >> GO TO 6. YES >> GO TO 7.
NO >> • Mark the box on the “Diagnostic Worksheet Chart”.
• Go to AT-186, " Vehicle Does Not Creep Backward in
"R" Position " .
• Continue “Road Test”. YES >> Go to
AT-58, " Cruise Test - Part 1 " .
NO >> • Mark the box on the “Diagnostic Worksheet Chart”.
• Go to AT-187, " Vehicle Does Not Creep Forward in
"D", "2" or "1" Position " .
• Continue “Road Test”.
Cruise Test - Part 1 INFOID:0000000004305323 SAT772B
SAT799A
SAT773B
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AT
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3. Push overdrive control switch. (OD OFF indicator lamp is off.)
4. Move selector lever to “P” position.
5. Start engine.
6. Move selector lever to “D” position.
7. Accelerate vehicle by constantly depressing accelerator pedal half-way.
Read gear position. Refer to AT-79, " CONSULT-III Func-
tion (TRANSMISSION) " .
Does vehicle start from D YES >> GO TO 2.
NO >> • Mark the box on the “D iagnostic Worksheet Chart”.
• Go to AT-188, " Vehicle Cannot Be Started from D .
• Continue “Road Test”. Vehicle Speed at Which Gear Shifting Occurs " .
Read gear position, throttl e opening and vehicle speed.
Refer to AT-79, " CONSULT-III Function (TRANSMISSION) " .
Does A/T shift from D YES >> GO TO 3.
NO >> • Mark the box on the “D iagnostic Worksheet Chart”.
• Go to AT-190, " A/T Does Not Shift: D
Not Kickdown: D .
• Continue “Road Test”. Vehicle Speed at Which Gear Shifting Occurs " .SAT775B
SAT495G