DTC 31

DTC 31: Low-Reverse Solenoid Valve System

CIRCUIT OPERATION
- A/T control relay supplies battery positive voltage to each solenoid valve (terminal 9 and 10).
- Solenoid valve closes when energized (on), and opens when deenergized (off). The PCM energize or deenergize solenoid valve, based on inputs data from sensors such as Throttle Position Sensor, Park/Neutral Position Switch, Stoplight Switch, Vehicle Speed Sensor, Input Shaft Speed Sensor, Output Shaft Speed Sensor, A/T Fluid Temperature Sensor etc.
- The PCM provides the ground to energize solenoid. The ground time is displayed in percent.
- As solenoid is energized or deenergized, it influences hydraulic pressure in the transmission applying and releasing elements.

DTC SET CONDITIONS
If the resistance value for a solenoid valve circuit is greater than 3.5 Ohms for 4 seconds at 100°C (212°F) or less than 2.6 Ohms for 4 seconds at 100°C (212°F), it judged that there is a short circuit or an open circuit in the solenoid valve and the diagnostic trouble code number "31" is displayed. The transmission is locked into 3rd gear as a fail-safe measure, and the "N" range light flashes once per second.

TROUBLESHOOTING HINTS (The most likely causes for this code to be set:)
- Malfunction of low-reverse solenoid valve
- Damaged harness, connector
- Malfunction of the PCM

DIAGNOSIS

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

CAUTION: To prevent damage to the scan tool M9991502, always turn the ignition switch to the "LOCK" (OFF) position before connecting or disconnecting the scan tool MB991502.

STEP 1. Using scan tool MB991502, read the A/T Diagnostic Trouble Code (DTC).

1) Connect scan tool MB991502 to the data link connector.
2) Turn the ignition switch to the "ON" position.
3) Read the A/T DTC.
4) Turn the ignition switch to the "LOCK"(OFF) position.
Q: Is the A/T diagnostic trouble code number "54" displayed?
YES: Refer to Code number 54-A/T control relay system.
NO: Go to Step 2.
STEP 2. Using scan tool MB991502, check actuator test item 01: Low-reverse Solenoid Valve.

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 the actuator test mode for item 01, Low-reverse Solenoid Valve.
- An operation sound should be heard from solenoid valve when the low-reverse solenoid valve is operated.

4) Turn the ignition switch to the "LOCK"(OFF) position.
Q: Is the solenoid operating properly?
YES: This malfunction can be intermittent.
NO: Go to Step 3.
STEP 3. Check the solenoid valve output voltage at PCM connector C-121 <2.4L Engine or C-123 <3.0L Engine> by backprobing.

1) Do not disconnect connector C-121 <2.4L Engine> or C 123 <3.0L Engine>.
2) Turn the ignition switch to the "ON" position.

3) Measure the voltage between terminal 129 and ground by backprobing.
- Voltage should be battery positive voltage.

4) Turn the ignition switch to the "LOCK"(OFF) position.
Q: Is the voltage normal?
YES: Go to Step 4.
NO: Go to Step 9.

STEP 4. Check connector C-121 <2.4L Engine or C-123 <3.0L Engine> at PCM for damage.
Q: Is the connector in good condition?
YES: Go to Step 5.
NO: Repair or replace it.

STEP 5. Check harness for damage between solenoid valve assembly connector B-110 terminal 6 and PCM connector G121 <2.4L Engine or C-123 <3.0L Engine> terminal 129.
Q: Is the harness wire in good condition?
YES: Go to Step 6.
NO: Repair or replace it.

STEP 6. Check connectors A-19X at A/T control relay for damage.
Q: Are the connectors in good condition?
YES: Go to Step 7.
NO: Repair or replace it.

STEP 7. Check harness for damage between solenoid valve assembly connector terminal 10 and A/T control relay connector A-19X terminal 3.
Q: Is the harness wire in good condition?
YES: Go to Step 8.
NO: Repair or replace it.
STEP 8. Using scan tool MB991502, check actuator test item 01: Low-reverse Solenoid Valve.

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

STEP 9. Check connector B-110 at solenoid valve assembly for damage.
Q: Is the connector in good condition?
YES: Go to Step 10.
NO: Repair or replace it.
STEP 10. Check the low-reverse solenoid valve at solenoid valve assembly connector B-110.

1) Disconnect connector B-110 and measure at the solenoid valve side.

2) Measure the resistance between terminal 6 and 10.
Standard value: 2.7 - 3.4 Ohms
Q: Is the resistance at the standard value?
YES: Go to Step 11.
NO: Replace the low-reverse solenoid valve.
STEP 11. Check the power supply voltage at solenoid valve assembly connector B-110.

1) Disconnect connector B-110 and measure at the harness side.
2) Turn the ignition switch to the "ON" position.

3) Measure the voltage between terminal 10 and ground.
- Voltage should be battery positive voltage.

4) Turn the ignition switch to the "LOCK"(OFF) position.
Q: Is the voltage normal?
YES: Go to Step 13.
NO: Go to Step 12.

STEP 12. Check connectors A-19X at A/T control relay for damage.
Q: Are the connectors in good condition?
YES: Repair it because of harness open circuit or short circuit to ground between solenoid valve assembly connector B-111 terminal 10 and A/T control relay connector A-19X terminal 3.
NO: Repair or replace it.

STEP 13. Check connectors C-121 <2.4L Engine> or C-123 <3.0L Engine> at PCM connector for damage.
Q: Are the connectors in good condition?
YES: Go to Step 14.
NO: Repair or replace it.

STEP 14. Check harness for open circuit, or short circuit to ground between solenoid valve assembly connector B-110 terminal 6 and PCM connector C-121 <2.4L Engine or C123 <3.0L Engine> terminal 129.
Q: Is the harness wire in good condition?
YES: Replace the PCM.
NO: Repair or replace it.