U Code Charts
DTC U1073: Bus OffCAUTION: Whenever the ECU is replaced, ensure that the communication circuit is normal.
TROUBLE JUDGMENT
DTC U1073 will be stored when the SRS-ECU ceases CAN communication (bus off) and then resumes the communication when the ignition switch is turned to the "LOCK" (OFF) position.
TECHNICAL DESCRIPTION (COMMENT)
The wiring harness wire or connectors may have loose, corroded, or damage terminals, or terminals pushed back in the connector, or the SRS-ECU may be defective.
TROUBLESHOOTING HINTS
- Defective connector(s) or wiring harness
- Malfunction of the SRS-ECU
DIAGNOSIS
Required Special Tools:
- MB991958: Scan Tool (MUT-III Sub Assembly)
- MB991824: Vehicle Communication Interface (V.C.I.)
- MB991827: MUT-III USB Cable
- MB991910: MUT-III Main Harness A (Vehicles with CAN communication)
STEP 1. Recheck for diagnostic trouble code.
Check again if the DTC is set.
1. Erase the DTC.
2. Turn the ignition switch to the "ON" position.
3. Check if the DTC is set.
4. Turn the ignition switch to the "LOCK" (OFF) position.
Q: Is the DTC set?
YES: Go to Step 2.
NO: There is an intermittent malfunction such as poor engaged connector(s) or open circuit (Refer to How to Cope with Intermittent Malfunction).
STEP 2. Check SRS-ECU connector C-115.
Q: Is the connector correctly engaged?
YES: Go to Step 3.
NO: Engage the connector correctly. Then go to Step 4.
STEP 3. Check data link connector C-23.
Q: Is the connector correctly engaged?
YES: Go to Step 4.
NO: Engage the connector correctly. Then go to Step 5.
STEP 4. Check the harness for short circuit between SRS-ECU connector C-115 (terminal No.32 and 43) and data link connector C-23 (terminal no.6 and 14).
Q: Is the harness wire between the SRS-ECU connector C-115 (terminal No.32 and 43) and data link connector C-23 (terminal no.6 and 14) in good condition?
YES: Erase the diagnostic trouble code memory, and check the diagnostic trouble code. If DTC U1073 sets, replace the SRS-ECU. Then go to Step 5.
NO: Repair the harness wire between SRS-ECU connector C-115 and data link connector C-23. Then go to Step 5.
STEP 5. Recheck for diagnostic trouble code.
Check again if the DTC is set.
1. Connect scan tool MB991958 to the data link connector
2. Turn the ignition switch to the "ON" position.
3. Check if the DTC is set.
4. Turn the ignition switch to the "LOCK" (OFF) position.
Q: Is the check result satisfactory?
YES: Return to Step 1.
NO: Replace the data link connector. On completion, check that the DTC is not reset.