Code No. C2021: Brake booster vacuum sensor fail output voltage (Brake electric vacuum pump)



caution
  • If there is any problem in the CAN bus lines, an incorrect diagnosis code may be stored. Prior to this diagnosis, diagnose the CAN bus lines (Refer to GROUP 54C - CAN Bus Diagnostics Table ).
  • Whenever ECU is replaced, ensure that the CAN bus lines are normal.

TROUBLE JUDGEMENT


The PHEV-ECU stores diagnosis code No. 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 brake booster vacuum sensor
  • Damaged harness or connector
  • Malfunction of PHEV-ECU

DIAGNOSIS PROCEDURE


STEP 1. M.U.T.-III CAN bus diagnostics


Use the M.U.T.-III to diagnose the CAN bus lines.

Q. Is the check result normal?

Go to Step 3.
Repair the CAN bus lines (Refer to GROUP 54C - Troubleshooting ). On completion, go to Step 2.

STEP 2. Check whether the diagnosis code is stored again.


Recheck if the diagnosis code is stored.
(1)Erase the diagnosis code.
(2)Turn on the power supply mode of the electric motor switch.
(3)Check if the diagnosis code is stored.

Q. Is the diagnosis code stored?

Go to Step 3.
The procedure is complete.

STEP 3. M.U.T.-III data list


Check that the following data list display contents are normal. (Refer to ).
Data list
  • Item 88: Brake pressure sensor (Physical)
OK: Changes in proportion to the depression stroke.

Q. Is the check result normal?

Go to Step 8.
Go to Step 4.

STEP 4. Voltage measurement at PHEV-ECU (VCSP terminal) connector terminal.


(1)Disconnect the connector, and measure at the wiring harness side.
(2)Measure the voltage between the PHEV-ECU (VCS1 terminal) connector and body earth.
OK: 5V (Power supply voltage)

Q. Is the check result normal?

Go to Step 6.
Go to Step 5.

STEP 5. Check the signal line for open and short circuit (Brake booster vacuum sensor and PHEV-ECU).



  • Brake booster vacuum sensor connector terminal No.2 and PHEV-ECU (VCS1 terminal) connector.

Q. 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. Resistance measurement at the PHEV-ECU (VCSN terminal) connector terminal No.1.


(1)Disconnect the connector, and measure at the wiring harness side.
(2)Resistance between terminal No.1 and body earth
OK: Continuity exists (2 Ω or less)

Q. Is the check result normal?

Replace the brake booster vacuum sensor. (Refer to GROUP 35A - Master cylinder assembly <LHD> or <RHD>). Then go to Step 8.
Go to Step 7.

STEP 7. Check the signal line for open and short circuit (Brake booster vacuum sensor and PHEV-ECU).



  • Brake booster vacuum sensor connector terminal No.1 and PHEV-ECU (VCSN terminal) connector.

Q. 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 8. Check whether the diagnosis code is stored again.


Recheck if the diagnosis code is stored.
(1)Erase the diagnosis code.
(2)Turn on the power supply mode of the electric motor switch.
(3)Check if the diagnosis code is stored.

Q. Is the diagnosis code stored?

Replace the PHEV-ECU (Refer to ).
The procedure is complete.