U1102

DTC U1102: ABS- ECU TIME- OUT

CAUTION:
- If the ECM or PCM output the DTC U1102, make sure to diagnose the CAN bus line.
- Before replacing the ECU, make sure that the communication circuit is operating normally.

DTC SET CONDITIONS

Check Conditions
- Battery positive voltage is 10 volts or higher.
- Engine is not cranked, or at least 3 seconds have passed since engine was cranked.

Judgement Criterion
- Unable to receive ABS- ECU signals through the CAN bus line.

COMMENT

Current Trouble
- Some of the possible causes are a harness or connector damage between the ECM or the PCM and the ABS- ECU on the CAN bus line, a failure in the ABS- ECU power supply system, a failure in the ABS- ECU, or a failure in the ECM or the PCM .

Past Trouble
- Proceed to troubleshoot based on a harness or connector damage on the CAN bus line between the ECM or the PCM and ABS- ECU, and a failure in the ABS power supply system. Refer to "How to cope with past trouble" (Refer to How to Use Troubleshooting/Inspection Service Points - How to Cope with Intermittent Malfunctions).

CAUTION: When the ignition key is maintained within the range "A" (i.e., the ignition switch IG2 is in OFF position but the cranking does not start) for more than 1 second, ECM or PCM stores DTC U1102 (the past trouble).

NOTE: If a malfunction occurred in the past, a failure cannot be discovered through the MB991958 CAN bus diagnosis even if there might be a problem with the CAN bus. In this case, refer to How to Use Troubleshooting/Inspection Service Points -

How to Cope with Intermittent Malfunctions P.00- 14. Furthermore, it is possible to narrow down the areas of the possible failures from the DTCs that are output by the ECUs, which are communicating on the CAN bus (Refer to CAN bus line Diagnostics Flow).

TROUBLESHOOTING HINTS (The most likely causes for this code to be set are:)
- CAN line harness damage or connector damage.
- ABS- ECU failed.
- ECM failed.
- PCM failed.

DIAGNOSIS

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

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

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 the "ON" position.
3. Diagnose CAN bus line.
4. Turn the ignition switch to the "LOCK" (OFF) position.

Q: Is the CAN bus line normal?

YES: Go to Step 2.

NO: Repair the CAN bus line. Refer to Can Bus Diagnostics Table. Then go to Step 6.

STEP 2. Using scan tool MB991958, read the diagnostic trouble code (DTC).

1. Connect scan tool MB991958 to the data link connector.
2. Turn the ignition switch to the "ON" position.
3. Read the ABS- DTC.
4. Turn the ignition switch to the "LOCK" (OFF) position.

Q: Is the ABS- DTC set?

YES: Refer to Anti- Lock Braking System- Diagnostic Trouble Code Chart.

NO: Go to Step 3.

STEP 3. Using scan tool MB991958, read the diagnostic trouble code (DTC).

1. Connect scan tool MB991958 to the data link connector.
2. Turn the ignition switch to the "ON" position.
3. Read the combination meter- DTC.
4. Turn the ignition switch to the "LOCK" (OFF) position.

Q: Is DTC U1102 set?

YES: Go to Step 4.

NO: Go to Step 5.

STEP 4. Using scan tool MB991958, read the diagnostic trouble code (DTC).

1. Connect scan tool MB991958 to the data link connector.
2. Turn the ignition switch to the "ON" position.
3. After the MFI- DTC has been deleted, read the MFI- DTC again.
4. Turn the ignition switch to the "LOCK" (OFF) position.

Q: Is DTC U1102 set?

YES: Replace the ABS- ECU. Then go to Step 6.

NO: It can be assumed that this malfunction is intermittent of CAN bus line between ECM or PCM and ABS- ECU. Refer to How to Use Troubleshooting/Inspection Service Points - How to Cope with Intermittent Malfunctions.

STEP 5. Using scan tool MB991958, read the diagnostic trouble code (DTC).

1. Connect scan tool MB991958 to the data link connector.
2. Turn the ignition switch to the "ON" position.
3. After the MFI- DTC has been deleted, read the MFI- DTC again.
4. Turn the ignition switch to the "LOCK" (OFF) position.

Q: Is DTC U1102 set?

YES: Replace the ECM or the PCM. When the ECM or the PCM is replaced, register the encrypted code. Then go to Step 6.

NO: It can be assumed that this malfunction is intermittent of CAN bus line between ECM or PCM and ABS- ECU. Refer to How to Use Troubleshooting/Inspection Service Points - How to Cope with Intermittent Malfunctions.

STEP 6. Using scan tool MB991958, read the diagnostic trouble code (DTC).

1. Connect scan tool MB991958 to the data link connector.
2. Turn the ignition switch to the "ON" position.
3. After the MFI- DTC has been deleted, read the MFI- DTC again.
4. Turn the ignition switch to the "LOCK" (OFF) position.

Q: Is DTC U1102 set?

YES: Retry the troubleshooting.

NO: The inspection is complete.