DTC 42

CIRCUIT OPERATION
DTC 41

DTC SET CONDITIONS
- If the output from the output shaft speed sensor multiplied by the 2nd gear ratio is not the same as the output from the input shaft speed sensor after shifting to 2nd gear has been completed, diagnostic trouble code number "42" is output. If diagnostic trouble code "42" is output four times, the transmission is locked into 3rd gear as a fail-safe measure, and the "N" range light flashes at a frequency of 1 Hz.

TROUBLESHOOTING HINTS
The most likely causes for this code to be set:
- Malfunction of the input shaft speed sensor
- Malfunction of the output shaft speed sensor
- Malfunction of the reverse clutch retainer
- Malfunction of the output shaft
- Malfunction of the second brake system
- Malfunction of the underdrive clutch system
- Noise generated

DIAGNOSIS





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

CAUTION: To prevent damage to the scan tool MB9911502, make sure the ignition switch is "OFF" before connecting or disconnecting the scan tool MB991502.

STEP 1. Is A/T diagnostic trouble code numbers "22" or "23" output?
If yes, refer to Code number 22 - Input shaft speed sensor system, DTC 22 or refer to Code number 23 - Output shaft speed sensor system. DTC 23
If no, go to Step 2.

STEP 2. Using an oscilloscope, check the input shaft speed sensor or output shaft speed sensor.
Required Special Tool: MB991709: Test Harness





1. Disconnect input shaft speed sensor connector B-16 or output shaft speed sensor connector B-15, and connect the special tool (test harness: MB9911709) in between.
2. Connect the oscilloscope probe to terminal 2 of input shaft speed sensor connector B-16 or output shaft speed sensor connector B-15.
3. Start the engine and run at 1,500 - 1,800 r/min <3.0L Engine>, 1,400 - 1,700 r/min <3.5L Engine> [Approximately 50 km/h (31 mph)]. Selector lever position should be "3".





4. Check the waveform.
The waveform should show a normal pattern as shown in the illustration.
5. Turn off the engine.
If the waveform shows a normal pattern, check the underdrive clutch system and second brake system, and repair or replace it. Refer to Transmission, Underdrive Clutch. Recheck for DTCs.
If the waveform does not show a normal pattern, go to Step 3.

STEP 3. Replace the input shaft speed sensor or the output shaft speed sensor. Then check the malfunction.





Replace the input shaft speed sensor or the output shaft speed sensor. Recheck for DTCs.
If the malfunction is eliminated, diagnosis is completed.
If the malfunction is not eliminated, go to Step 4.

STEP 4. Replace the reverse clutch retainer or output shaft.





Replace the reverse clutch retainer or output shaft. Refer to Transmission, Reverse and Overdrive Clutch.
If the malfunction is eliminated, diagnosis is complete.
If the malfunction is not eliminated, eliminate the source of the noise.