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DTC P1637: Malfunction of Memory Backup








DIAGNOSTIC FUNCTION


TCM checks the consistency between EEPROM and the backup memory.

DESCRIPTIONS OF MONITOR METHODS



MONITOR EXECUTION



MONITOR EXECUTION CONDITIONS (OTHER MONITOR AND SENSOR)


Other Monitor (There is no temporary DTC stored in memory for the item monitored below)
Sensor (The sensor below is determined to be normal)

LOGIC FLOW CHARTS (Monitor Sequence)




DTC SET CONDITIONS


Judgment Criteria

OBD-II DRIVE CYCLE PATTERN


Ignition switch : ON (start the engine and keep it for 10 seconds or more)

PROBABLE CAUSES



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?
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-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?
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 TCM.