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DTC P1637: Malfunction of Memory Backup
 
 
 
 
DIAGNOSTIC FUNCTION
The TCM determines that the system is defective if the calculated value does not correspond with the stored value.
 
 
DESCRIPTIONS OF MONITOR METHODS
The memory backup malfunction is detected.
 
 
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
Check Condition
  • Ignition switch is "ON" position.
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
 
 
DIAGNOSIS
Required Special Tools
  • MB992006: Extra fine probe
STEP 1. Scan tool (M.U.T.-IIISE) diagnostic trouble code.
Check whether a diagnostic trouble code other than P1637 is set.
Is diagnostic trouble code set?
Carry out the appropriate troubleshooting.
Go to Step 2.
 
STEP 2. Check for open circuit or short to ground in BATT, BAT2 line between the TCM connector and the battery.
Is the check result normal?
Replace the TCM.
Repair the connector(s) or wiring harness.