Manual A/C Diagnosis

DTC U1100: Powertrain Control Module Time-out (Related To Engine)

CAUTION:
- If DTC U1100 is set in the A/C-ECU, diagnose the CAN main bus line.
- Whenever the ECU is replaced, ensure that the communication circuit is normal.

NOTE: *: When the DTC relating to the CAN communication error are output, make sure of the vehicle equipment. When the vehicle is not equipped with the system the A/C-ECU communicates to, the DTC is always output. This is not abnormal.

TROUBLE JUDGMENT
The A/C-ECU receives engine control system-related signal from the powertrain control module. If the ECU cannot receive the signal, DTC U1100 will be set.

TECHNICAL DESCRIPTION (COMMENT)

Current trouble
- Connector(s) or wiring harness in the CAN bus lines between the powertrain control module and the A/C-ECU, the power supply system to the powertrain control module, the powertrain control module itself, or the A/C-ECU may be defective.

Past trouble
- If DTC U1100 is stored as a past trouble, carry out diagnosis with particular emphasis on wiring and connector(s) in the CAN bus line between the A/C-ECU and the powertrain control module, and the power supply system to the powertrain control module. If the connectors and wiring are normal, and obviously the ECU is the cause of the trouble, replace the ECU. If in doubt, do not replace the ECU.

NOTE: For a past trouble, you cannot find it by the scan tool CAN bus diagnostics even if there is a failure in CAN bus lines, 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 Explanation about the scan too CAN bus diagnostics). Explanation About the Scan Tool (M.U.T.-III) CAN Bus Diagnostics

TROUBLESHOOTING HINTS
- Powertrain control module failed
- Malfunction of the A/C-ECU
- Damaged harness wires and connectors

DIAGNOSIS

Required Special Tools:
- MB991223: Harness Set
- MB992006: Extra Fine Probe
- 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.

CAUTION: To prevent damage to scan tool (M.U.T.-III), always turn the ignition switch to the "LOCK" (OFF) position before connecting or disconnecting scan tool (M.U.T.-III).







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

Q: Is the CAN bus line found to be normal?

YES : Go to Step 2.

NO : Repair the CAN bus lines.

STEP 2. Using scan tool MB991958 read the powertrain control module diagnostic trouble code.







Check whether an engine and automatic transaxle DTCs are set or not.

1. Turn the ignition switch to the "ON" position.
2. Check for engine and transaxle DTCs.
3. Turn the ignition switch to the "LOCK" (OFF) position.

Q: Is the check result satisfactory?

YES : Diagnose the powertrain control module (Refer to Diagnostic Trouble Code Diagnostic Trouble Code Descriptions [2.4L] or Diagnostic Trouble Code Diagnostic Trouble Code Descriptions [3.8L]).

NO : Go to Step 3.

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







Check if a DTC, which relates to CAN communication-linked systems below, is set.
- Combination meter
DTC indicating a time-out error related to the engine or automatic transaxle control system
- ETACS-ECU
DTC indicating a time-out error related to the engine or automatic transaxle control system

1. Turn the ignition switch to the "ON" position.
2. Check for a DTC related to the relevant system.
3. Turn the ignition switch to the "LOCK" (OFF) position.

Q: Is the check result satisfactory?

YES : Go to Step 5.

NO : Go to Step 4.

STEP 4. Recheck for diagnostic trouble code.







Check again if the DTC is set.

1. Turn the ignition switch to the "ON" position.
2. Check if the DTC is set.
3. 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 powertrain control module and the A/C-ECU.

NO : Replace the powertrain control module. On completion, check that the DTC is not reset.

STEP 5. Recheck for diagnostic trouble code.







Check again if the DTC is set.

1. Turn the ignition switch to the "ON" position.
2. Check if the DTC is set.
3. 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 powertrain control module and the A/C-ECU.

NO : Replace the A/C-ECU. On completion, check that the DTC is not reset.