DTC C1786: Received Limp Home from Transaxle Control Module: Diagnosis

STEP 1. 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 (M.U.T.-III). Refer to "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. (Refer to EXPLANATION ABOUT THE SCAN TOOL (M.U.T.-III) CAN BUS DIAGNOSTICS )
4. Turn the ignition switch to the "LOCK" (OFF) position.
Q: Is the check result normal?
1. YES: Go to Step 2
2. NO: Repair the CAN bus lines (Refer to CAN BUS DIAGNOSTICS TABLE ).
STEP 2. Scan tool (M.U.T.-III) other system diagnostic trouble code.
Check the CVT diagnostic trouble code (Refer to DIAGNOSTIC TROUBLE CODE CHART ) or the A/T diagnostic trouble code (Refer to DIAGNOSTIC TROUBLE CODE CHART ).

Q: Is the diagnostic trouble code stored?
1. YES: Perform the relevant troubleshooting.
2. NO: Go to Step 3
STEP 3. Check the data list.
Using scan tool (M.U.T.-III), check the data list (Refer to DATA LIST REFERENCE TABLE ).
- Item 56: transmission fail
Q: Is the check result normal?
1. YES: Go to Step 4.
2. NO: Go to Step 4.
STEP 4. Check whether the diagnostic trouble code is stored again.
Q: Is diagnostic trouble code No. C1786 stored?
1. YES: Replace the ACC/FCM-ECU (Refer to ACC/FCM-ECU ).
2. NO: Intermittent malfunction (Refer to HOW TO COPE WITH INTERMITTENT MALFUNCTION ).