Diagnostic Procedure

STEP 1. Check if diagnosis code P1637 is erased by turning the ignition switch from the "LOCK" (OFF) position to the "ON" position.
Q: Is the check result normal?
1. YES: This diagnosis code will be set by disconnecting the battery. If the diagnosis code is not erased by turning the ignition switch to the "ON" position, it is judged to be normal.
2. NO: Go to Step 2.
STEP 2. Check for open circuit in power supply wiring harness
- Between relay box and C-40 TCM backup power supply connector (terminal No. 31)
- Between relay box and A-15X CVT control relay (terminal No. 4)
  Q: Is the check result normal?
  1. YES: Go to Step 3.
  2. NO: Repair the wiring harness.
STEP 3. Symptom recheck after erasing diagnosis code
Q: Is the check result normal?
1. YES: Intermittent malfunction
2. NO: Replace TCM.