Instrument Panel, Gauges and Warning Indicators

DTC U1100: ECM Or PCM Time-out (related To Engine)

CAUTION:
- If DTC U1100 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 or PCM have a terminator resistor.

DTC SET CONDITION
The combination meter receives engine control system-related signals from the ECM or PCM via CAN bus lines. If the display unit cannot receive the necessary signals, DTC U1100 will be set.

TECHNICAL DESCRIPTION (COMMENT)

CAUTION: If the ignition switch is turned to the ON position without starting the engine, DTC (past trouble) U1100 may be set on the combination meter (incorporating meter-ECU) after three minutes.

Current trouble
- Connector(s) or wiring harness in the CAN bus lines between the ECM or PCM and the combination meter, the power supply system to the ECM or PCM , the ECM or PCM 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 ECM or PCM and the combination meter, and the power supply system to the ECM or PCM . For diagnosis procedures, refer to "How to cope with past trouble" (Refer to How to Use Troubleshooting/Inspection Service Points).

NOTE: For a past trouble, you may not find it by the MUT-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.) 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 (Refer to CAN bus line Diagnostics Flow in Information Bus).

TROUBLESHOOTING HINTS
- The wiring harness or connectors may have loose, corroded, or damaged terminals, or terminals pushed back in the connector.
- Malfunction of ECM or PCM .
- Malfunction of combination meter

DIAGNOSIS

Required Special Tools:
- MB991958: Scan Tool (MUT-III Sub Assembly)
- MB991824: V.C.I.
- MB991827: MUT-III USB Cable
- MB991910: MUT-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.

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).

1. 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 (Refer to Information Bus, Diagnosis-Can Bus Diagnostic Chart).

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

Check if an MFI system diagnostic trouble code is set.

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: Diagnose the MFI system by referring to GROUP 13A, MFI Diagnosis - Diagnostic Trouble Code Chart P.13A-41 <2.4L ENGINE> or GROUP 13B, MFI Diagnosis - Diagnostic Trouble Code Chart P.13B-43 <3.8L ENGINE>.

NO: Go to Step 3.

STEP 3. Using scan tool MB991958, read the for any diagnostic trouble code.

1. Turn the ignition switch to the "ON" position.
2. Check if a diagnostic trouble code, which relates to CAN communication-linked systems below, is set.
ABS-ECU
- DTC U1100: ECM or PCM time-out (related to Engine)
A/C-ECU
- DTC U1100: ECM or PCM time-out (related to Engine)
ETACS-ECU
- DTC U1100: ECM or PCM time-out (related to Engine)
3. Turn the ignition switch to the "LOCK" (OFF) position.

Q: Is the DTC set?

YES: Go to Step 4.

NO: Go to Step 5.

STEP 4. Recheck for diagnostic trouble code.

When the ECM or PCM is replaced, register the encrypted code. Refer to Encrypted Code Registration Criteria Table in Antitheft and Alarm Systems, and then check that the diagnostic trouble code is not reset.

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 normally?

YES: An intermittent malfunction is suspected. refer to How to Use Troubleshooting/Inspection Service Points - How to Cope with Intermittent Malfunction.

NO: Replace the combination meter.

STEP 5. Recheck for diagnostic trouble code.

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