Code No. C1521: Vehicle speed sensor input error


caution
  • If the EPS-ECU sets the diagnosis code No. C1521, diagnose the CAN bus lines. If there is any fault in the CAN bus lines, an incorrect diagnosis code may be set.
  • Before replacing ECU, ensure that the communication circuit is normal.

DIAGNOSIS CODE SET CONDITIONS



CRITERIA FOR JUDGING MALFUNCTION



PROBABLE CAUSES



  • Defective wiring harness or connector between the ASC-ECU and the wheel speed sensor
  • Malfunction of the wheel speed sensor or vehicle speed detection encoder
  • Malfunction of the power supply to ASC-ECU
  • Malfunction of the ASC-ECU.
  • Malfunction of the EPS-ECU

DIAGNOSIS PROCEDURE

STEP 1. M.U.T.-III CAN bus diagnosis
Use the M.U.T.-III to diagnose the CAN bus lines.

Q. Is the check result normal?
Go to Step 2.
Repair the CAN bus lines. (Refer to GROUP 54C, Troubleshooting . ) After repairing the CAN bus lines, go to STEP 2.

STEP 2. Use M.U.T.-III to confirm a diagnosis code of other systems.
Check that the ASC-ECU sets a diagnosis code.

Q. Is the diagnosis code set?
Perform the troubleshooting for the ASC. Refer to .
Go to Step 3.

STEP 3. Diagnosis code recheck
Recheck if the diagnosis code is set.
(1)Turn the electric motor switch to the "LOCK" (OFF) → "ON" position.
(2)Check if the diagnosis code No. C1521 is set as a current trouble.

Q. Is diagnosis code C1521 set?
Replace the EPS-ECU, and then go to Step 4 .
Intermittent malfunction. (Refer to GROUP 00 - How to Cope with Intermittent Malfunction .)

STEP 4. Diagnosis code recheck
Recheck if the diagnosis code is set.
(1)Turn the electric motor switch to the "LOCK" (OFF) → "ON" position.
(2)Check if the diagnosis code No. C1521 is set.

Q. Is diagnosis code C1521 set?
Replace the hydraulic unit (ASC-ECU). (Refer to GROUP 35C - Hydraulic Unit .)
The diagnosis is complete.