Code No.31: Low-reverse solenoid valve system

OPERATION

Solenoid valve closes or opens according to the signals from the engine-A/T-ECU.
The engine-A/T-ECU energises or deenergises solenoid valve, based on input signals such as throttle position sensor opening angle, inhibitor switch, etc.

DIAGNOSIS CODE SET CONDITIONS

If the drive terminal voltage of the low-reverse solenoid valve is 3.0 V or less, it is judged that there is a short circuit or open circuit in the low-reverse solenoid valve, and diagnosis code 31 is set.
If diagnosis code 31 is set 4 times, the transmission is fixed in 3rd as a fail-safe measure.

PROBABLE CAUSES

Malfunction of low-reverse solenoid valve
Damaged harness wires and connectors
Malfunction of the engine-A/T-ECU

DIAGNOSIS PROCEDURE

STEP 1. M.U.T.-III diagnosis code

Q. Is diagnosis code 36 set?

	Go to Step 9.

	Go to Step 2.

STEP 2. M.U.T.-III actuator test

Item 01: Low-reverse solenoid valve

OK: Operating sound can be heard.

Q. Is the check result normal?

	Intermittent malfunction (Refer to GROUP 00 - How to Cope with Intermittent Malfunction ).

	Go to Step 3.

STEP 3. Connector check: B-109 A/T control solenoid valve assembly connector

Check for the contact with terminals.

Q. Is the check result normal?

Go to Step 4.

Repair the defective connector.

STEP 4. Measure the resistance at A/T control solenoid valve assembly connector B-109.

Disconnect the connector, and measure the resistance between terminal No.6 and No.10 at the solenoid valve side.
OK: 2.7 - 3.4 Ω (A/T fluid temperature 20°C)

Q. Is the check result normal?

Go to Step 5.

Check the low-reverse solenoid valve and solenoid valve harness.

STEP 5. Measure the voltage at engine-A/T-ECU connector C-114.

(1)Connect A/T control solenoid valve assembly connector B-109.

(2)Turn the ignition switch to the ON position.

(3)Measure the voltage between engine-A/T-ECU connector C-114 terminal No.128 and earth.
OK: System voltage

Q. Is the check result normal?

Go to Step 8.

Go to Step 6.

STEP 6. Connector check: C-114 engine-A/T-ECU connector

Check for the contact with terminals.

Q. Is the check result normal?

Go to Step 7.

Repair the defective connector.

STEP 7. Check the harness between A/T control solenoid valve assembly connector B-109 terminal No.6 and engine-A/T-ECU connector C-114 terminal No.128.

Check the output line for short or open circuit.

Q. Is the check result normal?

Go to Step 8.

Repair the wiring harness.

STEP 8. M.U.T.-III actuator test

Item 01: Low-reverse solenoid valve

OK: Operating sound can be heard.

Q. Is the check result normal?

	Intermittent malfunction (Refer to GROUP 00 - How to Cope with Intermittent Malfunction ).

	Replace the engine-A/T-ECU.

STEP 9. Connector check: B-109 A/T control solenoid valve assembly connector

Check for the contact with terminals.

Q. Is the check result normal?

Go to Step 10.

Repair the defective connector.

STEP 10. Measure the resistance at A/T control solenoid valve assembly connector B-109.

Disconnect the connector, and measure the resistance between terminal No.6 and No.10 at the solenoid valve side.
OK: 2.7 - 3.4 Ω (A/T fluid temperature 20°C)

Q. Is the check result normal?

Go to Step 11.

Check the solenoid valve harness.

STEP 11. Connector check: B-14X A/T control relay connector

Check for the contact with terminals.

Q. Is the check result normal?

Go to Step 12.

Repair the defective connector.

STEP 12. Check the harness between A/T control solenoid valve assembly connector B-109 terminal No.10 and A/T control relay connector B-14X terminal No.1.

Check the power supply line for short or open circuit.

Q. Is the check result normal?

Go to Step 8.

Repair the wiring harness.