CODE NO. U0172 Left side impact sensor (front) communication error










caution If the diagnosis code U0172 is set to SRS-ECU, be sure to diagnose the CAN bus line.

OPERATION
If an impact of set value or more is detected, the side impact sensor sends the coded acceleration data to SRS-ECU. Based on the acceleration data, SRS-ECU determines the necessity of side-airbag and curtain air bag deployment, and then turns ON the power supply circuit to the inflator.

TROUBLE JUDGMENT
The code is set if the communication between the left side impact sensor (front) and SRS-ECU is abnormal.

PROBABLE CAUSES

  • Malfunction of left side impact sensor (front)
  • Damaged wiring harness and connectors
  • Malfunction of SRS-ECU

DIAGNOSIS PROCEDURE

STEP 1. M.U.T.-III CAN bus diagnostics.
Use M.U.T.-III to diagnose the CAN bus lines.

Q. Is the check result normal?
Go to Step 2.
Repair the CAN bus line (Refer to GROUP 54C - Troubleshooting ).

STEP 2. Check whether the diagnosis code is reset.
(1)Connect the negative battery terminal.
(2)After erasing the diagnosis code memory, check the diagnosis code again.
(3)Disconnect the negative battery terminal.

Q. Is the diagnosis code No. U0172 set?
Go to Step 3.
Intermittent malfunction (Refer to GROUP 00 - How to Use Troubleshooting/Inspection Service Points - How to Cope with Intermittent Malfunction ).

STEP 3. Left side impact sensor (front) check.
(1)Check that the negative battery terminal is disconnected. If the negative battery terminal is connected, disconnect it.
(2)Alternate the right side impact sensor (front) and left side impact sensor (front), and then install the alternated sensors.
(3)Connect the negative battery terminal.
(4)After erasing the diagnosis code memory, check the diagnosis code again.
(5)Disconnect the negative battery terminal.

Q. Is the diagnosis code No. U0175 set?
Replace the left side impact sensor (front) (Refer to ).
Go to Step 4.

STEP 4. Wiring harness check between the D-121 left side impact sensor connector terminal No. 1/2 and the C-31 SRS-ECU connector terminal No. 49/50.

  • Open circuit check for the SRS-ECU power supply wire

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

STEP 5. Check whether the diagnosis code is reset.

Q. Is the diagnosis code No. U0172 set?
Replace SRS-ECU (Refer to ).
Intermittent malfunction (Refer to GROUP 00 - How to Use Troubleshooting/Inspection Service Points - How to Cope with Intermittent Malfunction ).