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DTC P1637: Memory Backup System
 
 
 
 
DIAGNOSTIC FUNCTION
TCM checks the consistency between EEPROM and the backup memory.
 
 
DESCRIPTIONS OF MONITOR METHODS
When the ignition switch is turned to the "ON" position, TCM determines that the writing to the EEPROM area had failed last time the ignition switch was turned to the "LOCK" (OFF) position.
 
 
MONITOR EXECUTION
  • Continuous
 
 
MONITOR EXECUTION CONDITIONS (OTHER MONITOR AND SENSOR)
Other Monitor (There is no temporary DTC stored in memory for the item monitored below)
  • Not applicable
Sensor (The sensor below is determined to be normal)
  • Not applicable
 
 
LOGIC FLOW CHARTS (Monitor Sequence)
 
 
DTC SET CONDITIONS
Judgment Criteria
  • Calculated checksum is not same as memorized checksum.
 
 
OBD-II DRIVE CYCLE PATTERN
Ignition switch: ON (start the engine and keep it for 10 seconds or more)
 
 
PROBABLE CAUSES
  • Damaged wiring harness and connectors
  • Malfunction of TCM (Faulty EEPROM)
 
 
DIAGNOSTIC PROCEDURE
STEP 1. Check if DTC P1637 is erased by turning the ignition switch from the OFF position to the ON position.
Is the check result normal?
This DTC will be stored by disconnecting the battery. If the DTC 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 line
Is the check result normal?
Go to Step 3.
Repair the wiring harness.
 
STEP 3. Symptom recheck after erasing DTC
Is the check result normal?
Intermittent malfunction
Replace TCM.