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DTC U1173: BMU LIN Slave not responding
 
 
caution
  • If there is any problem in the CAN bus lines, an incorrect DTC may be set. Prior to this diagnosis, diagnose the CAN bus lines (Refer to GROUP 54C - CAN Bus Diagnostics Table ).
  • Whenever ECU is replaced, ensure that the CAN bus lines are normal.
 
 
DTC SET CONDITIONS
The PHEV-ECU sets DTC U1173 when it cannot communicate with the BMU via LIN correctly.
 
 
 
PROBABLE CAUSES
  • Malfunction of LIN bus line.
  • Malfunction of the battery management unit (BMU).
  • Malfunction of the PHEV-ECU.
  • Noise interruption in LIN bus wires.
 
 
 
 
DIAGNOSIS
Required Special Tools
  • MB991223: Wiring harness set
  • MB992006: Extra fine probe
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 ground.
OK: Continuity exists (2 Ω or less)
Is the check result normal?
Go to Step 3.
Go to Step 2.
 
STEP 2. Check the ground line for open circuit (BMU and the body ground).
Check the wiring harness between BMU connector (terminal GND) and body ground.
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 (terminal BAT).
(1) Disconnect the connector, and measure at the wiring harness side.
(2) Measure the voltage between the BMU connector (terminal BAT) and body ground.
OK: Approximately 12 volts (battery positive voltage)
Is the check result normal?
Go to Step 5.
Go to Step 4.
 
STEP 4. Check the power supply line for open circuit and short circuit. (ETACS-ECU and the BMU).
Check the wiring harness between ETACS-ECU connector (terminal BUP2) and the BMU connector (terminal BAT).
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 circuit and short circuit (PHEV-ECU and the BMU).
Check the wiring harness between PHEV-ECU connector (terminal LIN1) and the BMU connector (terminal LIN1).
Is the check result normal?
Go to Step 6.
Repair the connector or wiring harness.
 
STEP 6. Using scan tool (M.U.T.-IIISE), check whether the DTC is set again.
Recheck the DTC.
(1) Erase the DTC.
(2) Turn off the power supply mode of the electric motor switch.
(3) Turn on the power supply mode of the electric motor switch.
(4) Check the DTC.
Is the DTC set?
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 ).