CODE NO. U0170 Left front impact sensor communication error
caution
If the diagnosis code U0170 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 front impact sensor sends the coded acceleration data to SRS-ECU. Based on the acceleration data, SRS-ECU determines the necessity of driver’s and passenger’s (front) 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 front impact sensor and SRS-ECU is abnormal.
PROBABLE CAUSES
Malfunction of left front impact sensor
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. U0170 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 front impact sensor check.
(1)Check that the negative battery terminal is disconnected. If the negative battery terminal is connected, disconnect it.
(2)Alternate the right front impact sensor and left front impact sensor, 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. U0171 set?
Replace the left front impact sensor (Refer to ).
Go to Step 4.
STEP 4. Wiring harness check between the A-39 left front impact sensor connector terminal No. 1/2 and the C-32 SRS-ECU connector terminal No. 22/21.
note
Prior to the wiring harness inspection, check the C-37 intermediate connector, and repair if necessary.
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. U0170 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 ).
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Go to Step 2.
Repair the CAN bus line (Refer to GROUP 54C - Troubleshooting 
).