Code No. P1637: Malfunction of Memory Backup













DIAGNOSTIC FUNCTION




JUDGMENT CRITERIA




PROBABLE CAUSES



  • Damaged wiring harness and connectors
  • Malfunction of CVT-ECU (Faulty EEPROM)

DIAGNOSTIC PROCEDURE


STEP 1. Check if diagnosis code P1637 is erased by turning the ignition switch from the OFF position to the ON position.


Q. Is the check result normal?

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.
Go to Step 2.

STEP 2. Check for open circuit in power supply wiring harness



  • Between relay box and C-135 CVT-ECU backup power supply connector (terminal No. 31)
  • Between relay box and A-18X CVT control relay (terminal No. 4)

Q. Is the check result normal?

Go to Step 3.
Repair the wiring harness.

STEP 3. Symptom recheck after erasing diagnosis code


Q. Is the check result normal?

Intermittent malfunction
Replace CVT-ECU.