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DTC U1801: Airbag communication line short
 
 
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 U1801 when it cannot communicate with the SRS-ECU correctly.
 
 
 
PROBABLE CAUSES
  • Damaged harness or connector.
  • Malfunction of the SRS-ECU.
  • Malfunction of the PHEV-ECU.
 
 
 
 
DIAGNOSIS
STEP 1. Check the signal line for open circuit and short to power supply circuit. (PHEV-ECU and SRS-ECU).
Check the wiring harness between PHEV-ECU connector (terminal ARBS) and the SRS-ECU connector (terminal ARBS).
Is the check result normal?
Go to Step 2.
Repair the connector or wiring harness.
 
STEP 2. 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) Depress the brake pedal, and turn on the power supply mode of the electric motor switch (READY operation).
(4) Check the DTC.
Is the DTC set?
Replace the SRS-ECU [Refer to GROUP 52B - SRS Control Unit (SRS-ECU) ]. Then go to Step 3.
The trouble can be an intermittent malfunction (Refer to GROUP 00, How to Cope with Intermittent Malfunction ).
 
STEP 3. 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) Depress the brake pedal, and turn on the power supply mode of the electric motor switch (READY operation).
(4) Check the DTC.
Is the DTC set?
Replace the PHEV-ECU (Refer to ).
The procedure is complete.