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DTC C2021: Vacuum SNS.fail output VOLT.(VP)
 
 
cautionWhenever ECU is replaced, ensure that the CAN bus lines are normal.
 
 
DTC SET CONDITIONS
The PHEV-ECU sets DTC C2021 when the output voltage of the brake booster vacuum sensor exceeds an upper limit value or drops below a lower limit.
 
 
 
PROBABLE CAUSES
  • Malfunction of the brake booster vacuum sensor.
  • Damaged harness or connector.
  • Malfunction of the PHEV-ECU.
 
 

 
 
DIAGNOSIS
Required Special Tools
  • MB991223: Wiring harness set
  • MB992006: Extra fine probe
STEP 1. Using scan tool (M.U.T.-IIISE), check the data list. <PHEV-ECU>
Check that the following data list display contents are normal (Refer to ).
Data list
  • Item No.88: Brake pressure sensor(Physical)
OK: Changes in proportion to the depression stroke.
Is the check result normal?
Go to Step 6.
Go to Step 2.
 
STEP 2. Voltage measurement at PHEV-ECU connector (terminal VCS1).
(1) Disconnect the connector, and measure at the wiring harness side.
(2) Measure the voltage between the PHEV-ECU connector (terminal VCS1) and body ground.
OK: Approximately 4.9 - 5.1 volts (Power supply voltage)
Is the check result normal?
Go to Step 4.
Go to Step 3.
 
STEP 3. Check the signal line for open circuit and short to ground circuit (Brake booster vacuum sensor and PHEV-ECU).
Brake booster vacuum sensor connector (terminal No.2) and PHEV-ECU connector (terminal VCS1).
Is the check result normal?
The trouble can be an intermittent malfunction (Refer to GROUP 00, How to Cope with Intermittent Malfunction ).
Repair the connector or wiring harness.
 
STEP 4. Resistance measurement at the brake booster vacuum sensor connector (terminal No.1).
(1) Disconnect the connector, and measure at the wiring harness side.
(2) Resistance between the brake booster vacuum sensor connector (terminal No.1) and body ground
OK: Continuity exists (2 Ω or less)
Is the check result normal?
Replace the brake booster vacuum sensor (Refer to GROUP 35A - Master Cylinder Assembly ). Then go to Step 6.
Go to Step 5.
 
STEP 5. Check the ground line for open circuit, short to ground circuit and short to power supply circuit (Brake booster vacuum sensor and PHEV-ECU).
Check the harness between brake booster vacuum sensor connector (terminal No.1) and PHEV-ECU connector (terminal VCSN).
Is the check result normal?
The trouble can be an intermittent malfunction (Refer to GROUP 00, How to Cope with Intermittent Malfunction ).
Repair the connector or wiring harness.
 
STEP 6. Using scan tool (M.U.T.-IIISE), check whether the DTC is set again.
Recheck the DTC.
(1) Erase the DTC.
(2) Turn off the power supply mode of the electric motor switch.
(3) Turn on the power supply mode of the electric motor switch.
(4) Check if the DTC.
Is the DTC set?
Replace the PHEV-ECU (Refer to ).
The procedure is complete.