Code No.C1860 Power supply voltage abnormality (high voltage)


caution
  • If the electric power steering-ECU sets diagnosis code No.C1860, diagnose the CAN bus lines. If there is any fault in the CAN bus lines, an incorrect diagnosis code may be set.
  • Whenever the ECU is replaced, ensure that the communication circuit is normal.


DIAGNOSIS CODE SET CONDITIONS

  • The power supply voltage is more than a predetermined voltage stored in the microcomputer, and the microcomputer determines that there is a problem in the power supply system.
    • Criteria for judging malfunction
    • Power supply voltage is more than 17.22 V

PROBABLE CAUSES

  • Defective battery
  • Charging system failed
  • Malfunction of the electric power steering-ECU

DIAGNOSIS PROCEDURE

STEP 1. Check the battery voltage.
Start the engine and measure the battery voltage.

Q. Does the voltage measure 16 V or less?
Go to Step 2.
Check the charging system and repair if necessary (Refer to GROUP 16, On-vehicle Service - Regulated Voltage Test ).

STEP 2. Check whether the diagnosis code is reset.

caution Before connecting or disconnecting the M.U.T.-III, turn the ignition switch to the "LOCK" (OFF) position.
Check again if the diagnosis code is set.
(1)Turn the ignition switch to the "ON" position.
(2)Erase the diagnosis code.
(3)Turn the ignition switch to the "LOCK" (OFF) position.
(4)Turn the ignition switch to the "ON" position.
(5)Check if the diagnosis code is set.
(6)Turn the ignition switch to the "LOCK" (OFF) position.
(7)Disconnect M.U.T.-III.

Q. Is diagnosis code C1860 set?

Replace the electric power steering-ECU (Refer to ).

The malfunction is intermittent. Refer to GROUP 00, How to Use Troubleshooting/Inspection Service Points - How to Cope with Intermittent Malfunction .