Combination Meter

DTC U1073: Bus off

CAUTION:

- If DTC U1073 is set in the combination meter, always diagnose the CAN bus lines.
- Whenever the ECU is replaced, ensure that the communication circuit is normal.

CIRCUIT OPERATION

Some instruments of the combination meter are linked to the CAN bus line. Both the combination meter and the ECM [M/T] or PCM [A/T] have a terminator resistor.

DTC SET CONDITION

If the combination meter ceases communicating once (i.e. bus off) and then returns to it, the combination meter will not communicate for five minutes immediately after that point.
This five minute period is called "Penalty mode." Immediately after the combination meter returns to communication, the DTC is set.

TECHNICAL DESCRIPTION (COMMENT)

The wiring harness or connectors may have loose, corroded, or damage terminals, or terminals pushed back in the connector, or the combination meter may be defective.

TROUBLESHOOTING HINTS

- The wiring harness or connectors may have loose, corroded, or damaged terminals, or terminals pushed back in the connector.
- 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. Recheck for diagnostic trouble code.

Recheck if the diagnostic trouble code is set.

(1)Turn the ignition switch "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 An intermittent malfunction is suspected. How to Cope With Intermittent Malfunctions.

NO Go to Step 3.

STEP 3. Recheck for diagnostic trouble code.

Replace the combination meter, and then check that the diagnostic trouble code is not reset.