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DIAGNOSIS


Required Special Tool:
• MB991958: Scan Tool (MUT-III Sub Assembly)
MB991824: V.C.I.
MB991827: MUT-III USB Cable
MB991911: MUT-III Main Harness B




STEP 1. Using scan tool MB991958, read the A/T diagnostic trouble code.


To prevent damage to scan tool MB991958, always turn the ignition switch to the "LOCK" (OFF) position before connecting or disconnecting scan tool MB991958.
(1) Connect scan tool MB991958 to the data link connector.
(2) Turn the ignition switch to the "ON" position.
(3) Check for A/T diagnostic trouble code.
(4) Turn the ignition switch to the "LOCK" (OFF) position.
Q: Is DTC set?

YES <DTC 22 set>: Refer to , DTC 22: Input Shaft Speed Sensor System.
YES <DTC 23 set>: Refer to , DTC 23: Output Shaft Speed Sensor System.
YES <DTC 31 set>: Refer to , DTC 31: Low-Reverse Solenoid Valve System.
YES <DTC 32 set>: Refer to , DTC 32: Underdrive Solenoid Valve System.
YES <DTC 33 set>: Refer to , DTC 33: Second Solenoid Valve System.
YES <DTC 34 set>: Refer to , DTC 34: Overdrive Solenoid Valve System.
NO: Go to Step 2 .




STEP 2. Check the hydraulic pressure.

Each hydraulic pressure of the elements below, which DTCs indicate, should be within the standard value. .
DTC41: Underdrive clutch and low-reverse brake.
DTC42: Underdrive clutch and second brake
DTC43: Underdrive clutch and overdrive clutch
DTC44: Overdrive clutch and second brake
DTC46: Reverse clutch and low-reverse brake
Q: Does the hydraulic pressures meet the standard value range?

YES: Go to Step 5 .
NO <out of the range in one place>: Go to Step 4 .
NO <out of the range in all places>: Go to Step 3 .




STEP 3. Adjust the line pressure.

Adjust the line pressure. Refer to , Line Pressure Adjustment. Then check the symptom.
Q: Is the symptom eliminated?

YES: The procedure is complete.
NO: Go to Step 4 .




STEP 4. 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. Refer to GROUP 23C, Valve Body . Replace the valve body assembly if the damages are thought to be irreparable. Then check the symptom.
Q: Is the symptom eliminated?

YES: The procedure is complete.
NO: Go to Step 6 .




STEP 5. Replace the PCM.

(1) Replace the PCM.
(2) Test drive the vehicle.
(3) Check for A/T diagnostic trouble code.
Q: Were any A/T DTCs set?

YES: Go to Step 6 .
NO: The procedure is complete.




STEP 6. Overhaul the A/T.

(1) Replace the following parts.
If DTC 41, DTC 42, or DTC 43 are set individually or in a group, replace the underdrive clutch. Refer to GROUP 23C, Underdrive Clutch and Input Shaft .
If DTC 43 or DTC 44 are set individually or in a group, replace the overdrive clutch. Refer to GROUP 23C, Reverse and Overdrive Clutch .
If DTC 46 is set, replace the reverse clutch. Refer to GROUP 23C, Reverse and Overdrive Clutch .
If DTC 41 or DTC 46 are set individually or in a group, replace the low-reverse brake. Refer to GROUP 23C, Transaxle .
If DTC 42 or DTC 44 are set individually or in a group, replace the second brake. Refer to GROUP 23C, Transaxle .
If DTC 41 is set, replace the one-way clutch. Refer to GROUP 23C, Planetary Gear .
(2) Test drive the vehicle.
(3) Check for A/T diagnostic trouble code.
Q: Are any A/T DTCs set again?

YES: An A/T DTC may have set due to external radio frequency interference (RFI) possibly caused by cellular phone activity, or aftermarket components installed on the vehicle.
NO: The procedure is complete.