Auto A/C Diagnosis
DTC U1415: Coding Not CompletedCAUTION:
- If DTC U1415 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.
TROUBLE JUDGMENT
The A/C-ECU receives the vehicle information signals from the ETACS-ECU via the CAN bus lines. If incorrect global coding data is received or coding data cannot be received with the ignition switch turned ON when the coding confirmation is completed, diagnostic trouble code U1415 is stored.
TROUBLESHOOTING HINTS
- Malfunction of the ETACS-ECU
- 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 MB991958, always turn the ignition switch to the "LOCK" (OFF) position before connecting or disconnecting scan tool MB991958.
1. Connect scan tool MB991958. Refer to "How to connect the Scan Tool (M.U.T.-III)." How to Connect the Scan Tool (M.U.T.-III)
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 line.
STEP 2. Using scan tool MB991958 read the ETACS-ECU diagnostic trouble code.
Check whether an ETACS DTC.
1. Turn the ignition switch to the "ON" position
2. Check for the DTC related to the ETACS-ECU
3. Turn the ignition switch to the "LOCK" (OFF) position.
Q: Is the DTC set?
YES : Diagnose the ETACS-ECU (Refer to Diagnostic Trouble Code). Diagnostic Trouble Code Descriptions
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.
- WCM [vehicles with WCM] B2204: Coding data unmatched
- KOS [vehicles with KOS] B2204: Coding data unmatched
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 DTC set?
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 DTC set?
YES : Replace the ETACS-ECU. On completion, check that the DTC is not reset.
NO : A poor connection, open circuit or other intermittent malfunction is present in the lines between the ETACS-ECU and the A/C-ECU.
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 DTC set?
YES : Replace the A/C-ECU. On completion, check that the DTC is not reset.
NO : A poor connection, open circuit or other intermittent malfunction is present in the lines between the ETACS-ECU and the A/C-ECU.