U1112

DTC U1112: SRS-ECU time-out

CAUTION:

- If DTC U1112 is set in the combination meter, always diagnose the CAN bus lines.
- Whenever the ECU is replaced, ensure that the communication circuit is normal.

DTC SET CONDITION

The combination meter communicates with the SRS-ECU through CAN bus lines. If it cannot receive all the necessary signals from the SRS-ECU, DTC U1112 is set.

TECHNICAL DESCRIPTION (COMMENT)

Current trouble

- Connector(s) or wiring harness in the CAN bus lines between the SRS-ECU and the combination meter, the power supply system to the SRS-ECU, the SRS-ECU itself, or the combination meter may be defective.
Past trouble

- Carry out diagnosis with particular emphasis on connector(s) or wiring harness in the CAN bus lines between the SRS-ECU and the combination meter, and the power supply system to the SRS-ECU. For diagnosis procedures, refer to "How to cope with past trouble" How to Cope With Intermittent Malfunctions ).
NOTE:
For a past trouble, you may not find it by the M.U.T.-III CAN bus diagnostics even if there is a failure in CAN bus lines. In this case, refer to How to Use Troubleshooting/Inspection Service Points - How to Cope with Intermittent Malfunction How to Cope With Intermittent Malfunctions .) and check the CAN bus lines. You can narrow down the possible cause of the trouble by referring to the DTC, which is set regarding the CAN communication-linked ECUs CAN Bus Line Diagnostics Flow ).

TROUBLESHOOTING HINTS

- The wiring harness or connectors may have loose, corroded, or damaged terminals, or terminals pushed back in the connector.
- Malfunction of SRS-ECU
- Malfunction of combination meter


DIAGNOSIS

Required Special Tools:

- MB991958: Scan Tool (M.U.T.-III Sub Assembly)
- MB991824: V.C.I.
- MB991827: M.U.T.-III USB Cable
- MB991910: M.U.T.-III Main Harness A

STEP 1. Using scan tool MB991958, diagnose the CAN bus line.

Use scan tool MB991958 to diagnose the CAN bus lines.





(1)
CAUTION:
To prevent damage to scan tool (MB991958), always turn the ignition switch to the "LOCK" (OFF) position before connecting or disconnecting scan tool (MB991958).

Connect scan tool MB991958 to the data link connector.
(2)Turn the ignition switch to "ON" position.
(3)Diagnose the CAN bus line.
(4)Turn the ignition switch to the "LOCK" (OFF) position.

Q. Is the check result satisfactory?

YES Go to Step 2.

NO Repair the CAN bus lines CAN Bus Diagnostics Chart).

STEP 2. Using scan tool MB991958, read the SRS diagnostic trouble code.

Check that the SRS-ECU sets a diagnostic trouble code.





(1)Turn the ignition switch to "ON" position.
(2)Read the diagnostic trouble code.
(3)Turn the ignition switch to the "LOCK" (OFF) position.

Q. Is the DTC set?

YES Supplemental Restraint System (SRS).

NO Go to Step 3.

STEP 3. Recheck for diagnostic trouble code.

Recheck if the diagnostic trouble code is set.





(1)Turn the ignition switch to "ON" position.
(2)Erase the diagnostic trouble code.
(3)Turn the ignition switch to the "LOCK" (OFF) position.
(4)Turn the ignition switch to "ON" position.
(5)Check if the diagnostic trouble code is set.
(6)Turn the ignition switch to the "LOCK" (OFF) position.

Q. Is the check result satisfactory?

YES A poor connection, open circuit or other intermittent malfunction is present in the lines between the SRS-ECU and the combination meter How to Cope With Intermittent Malfunctions).

NO Replace the combination meter.