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DTC P0620: Generator Control Circuit
 
 
 
 
CIRCUIT OPERATION
The ECM transmits request signals for the start and stop of power generation, and power generation voltage etc. to the generator by LIN communication. The generator transmits information on the power generation state etc. to the ECM by LIN communication.
 
 
TECHNICAL DESCRIPTION
The ECM compares the battery voltage with the voltage generated from the generator to check whether the electrical generation is normal.
 
 
DESCRIPTION OF MONITOR METHOD
The difference exceeds the specified value between the target generation voltage and the battery backup voltage.
 
 
DTC SET CONDITION
Check Conditions
  • Ignition switch is "ON" position.
  • The engine speed is 600 r/min or more.
  • The battery backup voltage is 13.5 volts or more.
Judgment Criteria
  • For 30 seconds, the final target generation voltage subtracted from the battery backup voltage equals 0.8 volt or more.
or
  • For 30 seconds, the battery backup voltage subtracted from the final target generation voltage equals 1.3 volts or more.
 
 
FAIL-SAFE AND BACKUP FUNCTION
  • Prohibits generator output suppression control against current consumers (operates as a normal generator).
 
 
TROUBLESHOOTING HINTS (The most likely causes for this code to be set are:)
  • Battery failed.
  • Drive belt failed.
  • Open/shorted generator circuit, harness damage or connector damage.
  • Battery backup circuit, harness damage or connector damage.
  • Generator failed.
  • ECM failed.
 
 
 
DIAGNOSIS
STEP 1. Checking engine start conditions.
Check whether the user uses the booster cable to start the engine.
noteThis diagnostic trouble code (DTC) can be output due to the battery voltage drop.
Have you ever used the booster cable to start the engine?
Delete the DTC and check end.
Go to Step 2.
 
STEP 2. Check the battery.
Refer to GROUP 54A, Battery - On-vehicle Service - Battery Test .
Are there any abnormalities?
Replace the battery. Then go to Step 9.
Go to Step 3.
 
STEP 3. Check the drive belt tension
Refer to GROUP 00, Maintenance Service - Drive Belt (For Water Pump and Generator) (Check Condition) .
Is the check result normal?
Go to Step 4.
Replace the drive belt. Then go to Step 9.
 
STEP 4. Check of short to ground, open circuit and harness damage in LNBS line between generator connector and ECM connector.
Is the harness wire in good condition?
Go to Step 5.
Repair it. Then go to Step 9.
 
STEP 5. Check of harness damage in BACK line between battery and ECM connector.
Is the harness wire in good condition?
Go to Step 6.
Repair it. Then go to Step 9.
 
STEP 6. Using scan tool (M.U.T.-IIISE), read the diagnostic trouble code (DTC).
(1)
cautionTo prevent damage to scan tool (M.U.T.-IIISE), always turn the ignition switch to the "LOCK" (OFF) position before connecting or disconnecting scan tool (M.U.T.-IIISE).
Connect scan tool (M.U.T.-IIISE). Refer to HOW TO CONNECT THE SCAN TOOL (M.U.T.-IIISE) .
(2) Start the engine and run at idle.
(3) After the DTC has been deleted, read the DTC again.
(4) Turn the ignition switch to the "LOCK" (OFF) position.
Is the DTC P0620 set?
Go to Step 7.
It can be assumed that this malfunction is intermittent. Refer to GROUP 00, How to Use Troubleshooting/ Inspection Service Points - How to Cope with Intermittent Malfunctions .
 
STEP 7. Replace the drive belt.
(1) Replace the drive belt.
(2) Start the engine and run at idle.
(3) After the DTC has been deleted, read the DTC again.
(4) Turn the ignition switch to the "LOCK" (OFF) position.
Is DTC P0620 set?
Go to Step 8.
The inspection is complete.
 
STEP 8. Replace the generator.
(1) Replace the generator.
(2) Start the engine and run at idle.
(3) After the DTC has been deleted, read the DTC again.
(4) Turn the ignition switch to the "LOCK" (OFF) position.
Is DTC P0620 set?
Replace the ECM (Refer to Removal and Installation ). Then go to Step 9.
The inspection is complete.
 
STEP 9. Using scan tool (M.U.T.-IIISE), read the diagnostic trouble code (DTC).
(1) Start the engine and run at idle.
(2) After the DTC has been deleted, read the DTC again.
(3) Turn the ignition switch to the "LOCK" (OFF) position.
Is DTC P0620 set?
Retry the troubleshooting.
The inspection is complete.