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DTC B1438 Side Impact Sensor (Front: LH) Communication Error
DTC B1439 Side Impact Sensor (Front: LH) Communication Impossible
 
 

cautionIf the diagnostic trouble code B1438 or B1439 is set to SRS-ECU, be sure to diagnose the CAN bus line.
 
 
CIRCUIT OPERATION
The side impact sensor transmits acceleration data to the SRS-ECU. The SRS-ECU then determines. if the side and/or curtain air bags should be inflated, and then sends an ignition signal. The side impact sensor also diagnoses itself, and sends a diagnostic trouble code to the SRS-ECU if a problem occurs.
 
 
DTC SET CONDITIONS
The diagnostic trouble code is set if the communication between the side impact sensor (Front: LH) and SRS-ECU is abnormal (No. B1438), or impossible (No. B1439).
 
 
TROUBLESHOOTING HINTS
  • Damaged wiring harnesses or connectors
  • Malfunction of the side impact sensor (Front: LH)
  • Malfunction of the SRS-ECU
 
 
DIAGNOSIS
STEP 1. M.U.T.-III CAN bus diagnostics
Use the M.U.T.-III to diagnose the CAN bus lines.
Is the check result normal?
Go to Step 2
Repair the CAN bus line (Refer to GROUP 54C, Diagnosis ).
 
STEP 2. Check whether the diagnostic trouble code is reset.
Check again if the diagnostic trouble code is set.
(1) Erase the diagnostic trouble code.
(2) Ignition: "LOCK" (OFF) position to "ON"
(3) On completion, check that the diagnostic trouble code is not reset.
Is the diagnostic trouble code set?
Go to Step 3
There is an intermittent malfunction such as poor engaged connector(s) or open circuit (Refer to GROUP 00, How to Cope with Intermittent Malfunction ).
 
STEP 3. Check the side impact sensor (Front: LH).
(1) Disconnect the negative battery terminal.
(2) Alternate the side impact sensor (Front: LH) and the side impact sensor (Front: RH), and then install the alternated sensor.
(3) Connect the negative battery terminal.
(4) Erase diagnostic trouble code from memory, and check the diagnostic trouble code.
Is diagnostic trouble code B1428 or B1429 set?
Replace the side impact sensor (Front: LH) with a new one (Refer to ). Go to Step 5.
Go to Step 4
 
STEP 4. Check the harness wires for open circuit and short circuit between SRS-ECU connector C-125 (terminal No.41 and 42) and side impact sensor (Front: LH) connector D-29 (terminal No.1 and 2).
Are the harness wires between SRS-ECU connector C-125 (terminal No.41 and 42) and side impact sensor (Front: LH) connector D-29 (terminal No.1 and 2) in good condition?
Go to Step 5
Repair the harness wires between SRS-ECU connector C-125 (terminal No.41 and 42) and side impact sensor (Front: LH) connector D-29 (terminal No.1 and 2).
 
STEP 5. Check whether the diagnostic trouble code is reset.
Is diagnostic trouble code B1438 or B1439 set?
Replace the SRS-ECU (Refer to ).
An intermittent malfunction is suspected (Refer to GROUP 00, How to Cope with Intermittent Malfunction ).