Code No. U1173: BMU LIN Slave not responding



caution Whenever ECU is replaced, ensure that the CAN bus lines are normal.

TROUBLE JUDGEMENT


The PHEV-ECU stores diagnosis code No. U1173 when it cannot communicate with the BMU via LIN correctly.

PROBABLE CAUSES



  • Malfunction of LIN bus
  • Malfunction of BMU
  • Malfunction of PHEV-ECU
  • Noise interruption in LIN bus wires

DIAGNOSIS PROCEDURE


STEP 1. Resistance measurement at the BMU connector.


(1)Disconnect the connector, and measure at the wiring harness side.
(2)Measure the resistance between GND terminal and body earth.
OK: Continuity exists (2 Ω or less)

Q. Is the check result normal?

Go to Step 3.
Go to Step 2.

STEP 2. Check the earth line for open circuit (BMU and the body earth).



  • Check the wiring harness between BMU (GND terminal) connector and body earth.

Q. Is the check result normal?

The trouble can be an intermittent malfunction (Refer to GROUP 00, How to Cope with Intermittent Malfunction ).
Repair the connector or wiring harness.

STEP 3. Voltage measurement at BMU connector (BAT terminal).


(1)Disconnect the connector, and measure at the wiring harness side.
(2)Measure the voltage between the BMU connector (BAT terminal) and body earth.
OK: System voltage

Q. Is the check result normal?

Go to Step 5.
Go to Step 4.

STEP 4. Check the power supply line for open and short circuit. (ETACS-ECU and the BMU).



  • Check the wiring harness between ETACS-ECU (BUP2 terminal) connector and the BMU (BAT terminal) connector.

Q. Is the check result normal?

The trouble can be an intermittent malfunction (Refer to GROUP 00, How to Cope with Intermittent Malfunction ).
Repair the connector or wiring harness.

STEP 5. Check the power supply line for open and short circuit. (PHEV-ECU and the BMU).



  • Check the wiring harness between PHEV-ECU (LIN1 terminal) connector and the BMU (LIN1 terminal) connector.

Q. Is the check result normal?

Go to Step 6.
Repair the connector or wiring harness.

STEP 6. Check whether the diagnosis code is stored again.


Recheck if the diagnosis code is stored.
(1)Erase the diagnosis code.
(2)Turn on the power supply mode of the electric motor switch.
(3)Check if the diagnosis code is stored.

Q. Is the diagnosis code stored?

Replace the PHEV-ECU (Refer to ).
A poor connection, open circuit or other intermittent malfunction in the LIN bus line between the PHEV-ECU and the BMU.(Refer to GROUP 00, How to Cope with Intermittent Malfunction ).