Code No.51: Valve Relay ON Defective












caution If there is any problem in the CAN bus lines, an incorrect diagnosis code may be set. Diagnose the CAN bus lines before the diagnosis codes (Refer to GROUP 54D, CAN bus-line diagnostic flow ).

OPERATION
HBB is supplied with power for drive of each solenoid valve from the fusible link No. 31 by turning ON the valve relay, and the drive of each solenoid valve is controlled by ASTC-ECU.

DIAGNOSIS CODE SET CONDITIONS
Diagnosis code No. 51 is set if ASTC-ECU judges that power for the solenoid valve is supplied when the valve relay is turned OFF for the initial check conducted with the ignition switch ON.

PROBABLE CAUSES
The most likely causes for these diagnosis codes to set are:

  • Damaged wiring harness or connector
  • Malfunction of the valve relay
  • Malfunction of the ASTC-ECU

DIAGNOSIS

STEP 1. M.U.T.-III CAN bus diagnostics
caution Before connecting or disconnecting the M.U.T.-III, turn the ignition switch to the "LOCK" (OFF) position.
(1)Connect M.U.T.-III to the 16-pin diagnosis connector.
(2)Turn the ignition switch to the "ON" position.
(3)Diagnose the CAN bus line.
(4)Turn the ignition switch to the "LOCK" (OFF) position.

Q. Is the check result normal?
Go to Step 3.
Repair the CAN bus line (Refer to GROUP 54D, CAN bus line Diagnostic flow ). Then go to Step 2.

STEP 2. Check whether the diagnosis code is reset.
caution Before connecting or disconnecting the M.U.T.-III, turn the ignition switch to the "LOCK" (OFF) position.
(1)Turn the ignition switch to the "ON" position.
(2)Erase the diagnosis code.
(3)Turn the ignition switch to the "LOCK" (OFF) position.
(4)Turn the ignition switch to the "ON" position.
(5)Check if the diagnosis code is set.
(6)Turn the ignition switch to the "LOCK" (OFF) position.

Q. Is code No.51 set?
Go to Step 3.
The procedure is complete.

STEP 3. Check the valve relay.
Refer to .

Q. Is the check result normal?
Go to Step 4.
Replace the valve relay. Then go to Step 9.

STEP 4. Check B-17X valve relay connector, B-109 diode connector and D-232, D-233 ASTC-ECU connector for loose, corroded or damaged terminals, or terminals pushed back in the connector.

Q. Is the check result normal?
Go to Step 5.
Repair or replace the damaged component(s). Then go to Step 9.

STEP 5. Check the harness wire between B-17X valve relay connector terminal No.4 and earth.
Check for open circuit to power supply.

Q. Is the check result normal?
Go to Step 6.
Repair the wiring harness. Then go to Step 9.

STEP 6. Check the harness wire between B-17X valve relay connector terminal No.2 and D-232 ASTC-ECU connector terminal No.62.
caution When checking the wiring harness continuity using the circuit tester, be sure to apply voltage in a correct direction because the diode is mounted on the circuit.
Check for open circuit or short to power supply.

Q. Is the check result normal?
Go to Step 7.
Repair the wiring harness. Then go to Step 9.

STEP 7. Check the harness wire between B-17X valve relay connector terminal No.1 and D-233 ASTC-ECU connector terminal No.18.
Check for short circuit to valve relay power supply.

Q. Is the check result normal?
Go to Step 8.
Repair the wiring harness. Then go to Step 9.

STEP 8. Check whether the diagnosis code is reset.
Check again if the diagnosis code is set.
(1)Turn the ignition switch to the "ON" position.
(2)Erase the diagnosis code.
(3)Turn the ignition switch to the "LOCK" (OFF) position.
(4)Turn the ignition switch to the "ON" position.
(5)Check if the diagnosis code is reset.
(6)Turn the ignition switch to the "LOCK" (OFF) position.

Q. Is code No.51 set?
Replace the ASTC-ECU. Then go to Step 9.
It can be assumed that this malfunction is intermittent. Refer to GROUP 00, How to Use Troubleshooting/Inspection Service Points - How to Cope with Intermittent Malfunction .

STEP 9. Check whether the diagnosis code is reset.
(1)Turn the ignition switch to the "ON" position.
(2)Erase the diagnosis code.
(3)Turn the ignition switch to the "LOCK" (OFF) position.
(4)Turn the ignition switch to the "ON" position.
(5)Check if the diagnosis code is set.
(6)Turn the ignition switch to the "LOCK" (OFF) position.

Q. Is code No.51 set?
Repeat the troubleshooting from Step 1.
The procedure is complete.