DTC 42

DTC 42: 2nd Gear Incorrect Ratio

CIRCUIT OPERATION
^ A coil built into the input shaft speed sensor generates pulse signal of 0 - 5 volts at both ends of this coil when the input shaft rotates. The pulse signal frequency increases with the rise in input shaft speed.
^ Both ends of the coil are connected to the PCM (terminals 16 and 103) via the input shaft speed sensor connector (terminals 1 and 2).
^ The PCM detects the input shaft speed with the signal input to terminal (terminal 103).
^ A coil built into the output shaft speed sensor generates pulse signal of 0 - 5 volts at both ends of this coil when the output shaft rotates. The pulse signal frequency increases with the rise in output shaft speed.
^ Both ends of the coil are connected to the PCM (terminals 16 and 104) via the output shaft speed sensor connector (terminals 1 and 2).
^ The PCM detects the output shaft speed with the signal input to terminal (terminal 104).

DTC SET CONDITIONS
If the output from the output shaft speed sensor multiplied by the 1st gear ratio is not the same as the output from the input shaft speed sensor after shifting to 1st gear has been completed, diagnostic trouble code number "41" set? If diagnostic trouble code number "41" is output four times, the transmission is locked into 3rd gear as a fail-safe measure.

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 PCM
^ Malfunction of the underdrive clutch retainer
^ Malfunction of the transfer drive gear or driven gear
^ Malfunction of the low-reverse brake system (for code number "41," "46")
^ Malfunction of the underdrive clutch system (for code number "41," "42,""43")
^ Malfunction of the second brake system (for code number "42," "44")
^ Malfunction of the overdrive clutch system (for code number "43," "44")
^ Malfunction of the reverse clutch system (for code number "46")
^ Noise generated

DIAGNOSIS

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

STEP 1. Using scan tool MB991502, read the A/T diagnostic trouble code.

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. Turn the ignition switch to the "ON" position.
3. Read the A/T diagnostic trouble code.
4. Turn the ignition switch to the "LOCK" (OFF) position.
Q: Is A/T diagnostic trouble code numbers "22" or "23" set?
YES: Refer to code number 22: Input Shaft Speed Sensor System, or refer to code number 23: Output Shaft Speed Sensor System.
NO: Go to Step 2.

STEP 2. Using scan tool MB991502, check actuator test.
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 actuator test mode for following items.
a. item 01: Low-reverse Solenoid Valve
b. item 02: Underdrive Solenoid Valve
c. item 03: Second Solenoid Valve
d. item 04: Overdrive Solenoid Valve
^ An operation sound should be heard from solenoid valve when solenoid valve is operated.
4. Turn the ignition switch to the "LOCK" (OFF) position.
Q: Is the solenoid valve operating properly?
YES: Go to Step 3.
NO: Replace the corresponding solenoid valve.

STEP 3. Using the oscilloscope, check the waveform at PCM connectors C-114 and C-120 by backprobing.

1. Do not disconnect connectors C-114 and C-120.

2. Connect an oscilloscope probe to PCM connector C-114 terminal 103 and to PCM connector C-120 terminal 16 by backprobing.
3. Start the engine and run at constant speed of 50 km/h (31 mph). (Gear range: 3rd gear)

4. Check the waveform.
^ The waveform should show a pattern similar to the illustration. The maximum value should be 4.8 volts and more and the minimum value 0.8 volts and less. The output waveform should not contain electrical noise.
5. Turn the ignition switch to the "LOCK" (OFF) position.
Q: Is the waveform normal?
YES: Go to Step 8.
NO: Go to Step 4.

STEP 4. Check connectors B-110 at input shaft speed sensor and C-114 at PCM for damage.
Q: Are the connectors in good condition?
YES: Go to Step 5.
NO: Repair or replace the defective connectors.

STEP 5. Check harness for damage between input shaft speed sensor connector B-110 terminal 2 and PCM connector C-114 terminal 103.
Q: Is the harness wire in good condition?
YES: Go to Step 6.
NO: Repair it.

STEP 6. Replace the input shaft speed sensor.
1. Replace the input shaft speed sensor.
2. Test drive the vehicle.
3. Check for A/T diagnostic trouble code.
Q: Is A/T diagnostic trouble code output?
YES: Go to Step 7.
NO: The inspection is complete.

STEP 7. Replace the underdrive clutch retainer.
1. Replace the underdrive clutch retainer.
2. Test drive the vehicle.
3. Check for A/T diagnostic trouble code.
Q: Is the A/T diagnostic trouble code output?
YES: The A/T diagnostic trouble code may have set due to external radio frequency (RFI), possibly caused by cellular phone activity, after market components installed on the vehicle, etc.
NO: The inspection is complete.

STEP 8. Using the oscilloscope, check the waveform at PCM connectors C-114 and C-120 by backprobing.

1. Do not disconnect connectors C-114 and C-120.

2. Connect an oscilloscope probe to PCM connector C-114 terminal 104 and to PCM connector C-120 terminal 16 by backprobing.
3. Start the engine and run at constant speed of 50 km/h (31 mph). (Gear range: 3rd gear)

STEP 9. Check connectors B-109 at output shad speed sensor and C-114 at PCM for damage.
Q: Are the connectors in good condition?
YES: Go to Step 10.
NO: Repair or replace the defective connectors.

STEP 10. Check harness for damage between output shaft speed sensor connector B-109 terminal 2 and PCM connector C-114 terminal 104.
Q: Is the harness wire in good condition?
YES: Go to Step 11.
NO: Repair it.

STEP 11. Replace the output sham speed sensor.
1. Replace the output shaft speed sensor.
2. Test drive the vehicle.
3. Check for A/T diagnostic trouble code.
Q: Is the A/T diagnostic trouble code output?
YES: Go to Step 12.
NO: The inspection is complete.

STEP 12. Replace the transfer drive gear or driven gear.
1. Replace the transfer drive gear or driven gear.
2. Test drive the vehicle.
3. Check for A/T diagnostic trouble code.
Q: Is the A/T diagnostic trouble code output?
YES: The A/T diagnostic trouble code may have set due to external radio frequency (RFI), possibly caused by cellular phone activity, after market components installed on the vehicle, etc.
NO: The inspection is complete.

STEP 13. Replace the valve body.
1. Replace the valve body.
2. Test drive the vehicle.
3. Check for A/T diagnostic trouble code.
Q: Is the A/T diagnostic trouble code output?
YES: Go to Step 14.
NO: The inspection is complete.

STEP 14. Replace the PCM.
1. Replace the PCM.
2. Test drive the vehicle.
3. Check for diagnostic trouble code.
Q: Is the A/T diagnostic trouble code output?
YES: Go to Step 15.
NO: The inspection is complete.

STEP 15. Overhaul the A/T.
1. Replace the following parts.
^ If DTC No. 41, No. 42, No. 43 are output individually or in a group, replace the underdrive clutch.
^ If DTC No. 43, No. 44 are output individually or in a group, replace the overdrive clutch.
^ If DTC No. 46 is output, replace the reverse clutch.
^ If DTC No. 41 and No. 46 are output, replace the low/reverse brake.
^ If DTC No. 42 and No. 44 are output, replace the second brake.
^ If DTC No. 41 is output, replace the one-way clutch.
2. Test drive the vehicle.
3. Check for A/T diagnostic trouble code.
Q: Is the A/T diagnostic trouble code output again?
YES: The A/T diagnostic trouble code may have set due to external radio frequency (RFI), possibly caused by cellular phone activity, after market components installed on the vehicle, etc.
NO: The inspection is complete.