Inspection Procedure 10

INSPECTION PROCEDURE 10: Does Not Shim Properly All Points (Early or Late Shift Points)

COMMENT
If all shift points are early or late while driving, the cause is probably a malfunction of the output shaft speed sensor, throttle position sensor or a solenoid valve.

TROUBLESHOOTING HINTS (The most likely causes for this code to be set:)
^ Malfunction of the output shaft speed sensor
^ Malfunction of the throttle position sensor
^ Malfunction of each solenoid valve
^ Abnormal line pressure
^ Malfunction of the valve body
^ Malfunction of the PCM

DIAGNOSIS

Required Special Tool: MB991502: Scan Tool (MUT-II)





STEP 1. Using scan tool MB9915021 check data list item 23: Output Shaft Speed Sensor.

CAUTION: To prevent damage to scan tool MB991502, always turn the ignition switch to "LOCK" (OFF) position before connecting or disconnecting scan tool MB991502.

1. Connect scan tool MB991502 to the data link connector.
2. Start the engine.
3. Set scan tool MB991502 to data reading mode for item 23: Output Shaft Speed Sensor.
^ When driving at constant speed of 50 km/h (31 mph), the display should be 1,600 - 1,900 r/min (Gear range: 3rd gear)
4. Turn the ignition switch to the "LOCK" (OFF) position.
Q: Is the sensor operating properly?
YES: Go to Step 2.
NO: Refer to diagnostic trouble code number 23: Output shaft speed sensor system.





STEP 2. Using scan tool MB991502, check data list item 11: Throttle position sensor.
1. Connect scan tool MB991502 to the data link connector.
2. Turn the ignition switch to the "ON" position.
3. Set scan tool MB991502 to data reading mode for item 11: Throttle Position Sensor.
^ With the throttle valve in idle position, voltage should be between 535 and 735 mV.
^ With the throttle valve in full-open position, voltage should be between 4,500 and 5,500 mV.
4. Turn the ignition switch to the "LOCK" (OFF) position.
Q: Is the sensor operating properly?
YES: Go to Step 3.
NO: Check the throttle position sensor. Then check the malfunction.








STEP 3. Using scan tool MB991502, check data list.
1. Connect scan tool MB991502 to the data link connector.
2. Start the engine.
3. Set scan tool MB991502 to data reading mode for following items.
a. Item 31: Low-Reverse Solenoid Valve Duty Percent
b. Item 32: Underdrive Solenoid Valve Duty Percent
c. Item 33: Second Solenoid Valve Duty Percent
d. Item 34: Overdrive Solenoid Valve Duty Percent
^ Check that the values shown are displayed when each data list item is entered.
4. Turn the ignition switch to the "LOCK" (OFF) position.
Q: Are the solenoid valves operating properly?
YES: Go to Step 4.
NO: Go to Step 6.

STEP 4. Adjust the line pressure.
Adjust the line pressure. Then check the symptom.
Q: Is the symptom eliminated?
YES: Diagnosis is complete.
NO: Go to Step 5.





STEP 5. Disassemble and clean the valve body.
Check the O-ring installation bolts for looseness and the valve body for damage. Repair or replace the faulty parts.
Q: Is the repair possible and the symptom eliminated?
YES: Diagnosis is complete.
NO: Replace the valve body assembly. Then check the symptom. Go to Step 7.





STEP 6. Replace each solenoid valve.
Replace the faulty solenoid valve with a new one.
Q: Is the symptom eliminated?
YES: Diagnosis is complete.
NO: Go to Step 7.

STEP 7. Replace the PCM.
Q: Is the symptom eliminated?
YES: Diagnosis is complete.
NO: Start over at Step 1.