Code No. P1B2B: Water pump power supply relay excitation circuit, open circuit/short to earth


WATER PUMP CIRCUIT






OPERATION



  • The water pump relay is controlled by the EV-ECU and supplies the power to the water pump.
  • The EV-ECU monitors the water pump relay coil drive circuit.

DIAGNOSIS CODE SET CONDITIONS



  • When the water pump relay coil drive circuit monitor is set to ON while the water pump relay stop command is underway, the diagnosis code No. P1B2B will be set.

PROBABLE CAUSES



  • Damaged wiring harness or connector(s)
  • Malfunction of the water pump relay
  • Malfunction of the EV-ECU

DIAGNOSIS PROCEDURE

STEP 1. M.U.T.-III actuator test and service data
Conduct the actuator test, and check the water pump relay. (Refer to .)
Actuator test
  • Item No. 10 : Water pump power supply relay drive
OK: The water pump operates normally.

Q. Is the check result normal?
Go to Step 7.
Check the water pump relay. (Refer to GROUP 14 - On-vehicle Service - Water Pump Relay Continuity Check .) Then go to Step 2.

STEP 2. Measure the voltage at A-09X water pump relay (relay box) connector.
(1)Disconnect the relay, and measure the voltage at the wiring harness side.
(2)Turn the electric motor switch to the "ON" position.
(3)Measure the voltage between the A-09X water pump relay (relay box) connector terminal No. 3 and the body earth.
OK: Battery voltage

Q. Is the check result normal?
Go to Step 5.
Go to Step 3.

STEP 3. Connector check: A-09X water pump relay (relay box) connector

Q. Is the check result normal?
Go to Step 4.
Correct or replace the relay box.

STEP 4. Check the wiring harness between A-09X water pump relay (relay box) connector terminal No. 3 and A-08X EV control relay (relay box) connector terminal No. 1.
Check the power supply line for open circuit.

Q. Is the check result normal?
Go to Step 5.
Repair the wiring harness.

STEP 5. Connector check: C-108 EV-ECU connector

Q. Is the check result normal?
Go to Step 6.
Repair the damaged connector.

STEP 6. Check the wiring harness between A-09X water pump relay (relay box) connector terminal No. 2 and C-108 EV-ECU connector terminal No. 56.
Check the power supply line for open circuit.

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

STEP 7. Diagnosis code recheck
Check again if the diagnosis code is set to the EV-ECU.
(1)Erase the stored diagnosis code.
(2)Set the electric motor switch from the "LOCK" (OFF) position to the "ON" position.
(3)Check if the diagnosis code is set.

Q. Is the diagnosis code set?
Replace the EV-ECU. (Refer to .) Then go to Step 8.
Intermittent malfunction (Refer to GROUP 00 - How to Use Troubleshooting/Inspection Service Points - How to Cope with Intermittent Malfunction .)

STEP 8. Diagnosis code recheck
Check again if the diagnosis code is set to the EV-ECU.
(1)Erase the stored diagnosis code.
(2)Set the electric motor switch from the "LOCK" (OFF) position to the "ON" position.
(3)Check if the diagnosis code is set.

Q. Is the diagnosis code set?
Return to Step 1.
The diagnosis is complete.