Code No.C1860: Power supply high voltage
Code No.C1861: Power supply low voltage


<LH drive vehicles>

<RH drive vehicles>

caution If there is any problem in the CAN bus lines, an incorrect diagnosis code may be set. Prior to this diagnosis, diagnose the CAN bus lines (Refer to GROUP 54F, CAN bus-line diagnostic flow ).

OPERATION


The ABS-ECU is energized by the ignition switch (IG1) through multi-purpose fuse 2 and the ABS-ECU terminal 20.

DIAGNOSIS CODE SET CONDITIONS


C1860 will be set when the power supply voltage to the ABS-ECU has decreased to a predetermined value or lower. C1861 will be set when the power supply voltage to the ABS-ECU has increased to a predetermined value or higher.

PROBABLE CAUSES



DIAGNOSIS

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

caution Before connecting or disconnecting the M.U.T.-III, turn the ignition switch to the "LOCK" (OFF) position.
(1)Connect M.U.T.-III to the 16-pin diagnosis connector.
(2)Turn the ignition switch to the "ON" position.
(3)Diagnose the CAN bus line.
(4)Turn the ignition switch to the "LOCK" (OFF) position.

Q. Is the check result normal?

Go to Step 3.

Repair the CAN bus line (Refer to GROUP 54F, CAN bus line Diagnostic flow ). Then go to Step 2.

STEP 2. M.U.T.-III diagnosis code

caution Before connecting or disconnecting the M.U.T.-III, turn the ignition switch to the "LOCK" (OFF) position.
(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.

Q. Is code No.C1860 or C1861 set?

Go to Step 3.

The procedure is complete.

STEP 3. Check the battery.
Check the battery (Refer to GROUP 54A, Battery test ).

Q. Is the check result normal?
Go to Step 4.
Charge or replace the battery.

STEP 4. Check the charging system.
Check the charging system (Refer to GROUP 16, Charging system ).

Q. Is the check result normal?
Go to Step 5.
Repair or replace the charging system component(s).

STEP 5. Voltage measurement at ABS-ECU connector A-03.

(1)Disconnect the connector A-03, and connect special tool ABS Check Harness (MB991974) to the wiring harness-side connector.
note Do not connect special tool ABS Check Harness (MB991974) to the ABS-ECU.
(2)Turn the ignition switch to the "ON" position.
(3)Measure the voltage between terminal 20 and earth.
OK: System voltage

Q. Is the check result normal?

Go to Step 7.

Go to Step 6.

STEP 6. Check the following connectors.










  • ABS-ECU connector A-03
  • Junction block connectors C-202 and C-203
  • Joint connector C-01 <LH drive vehicles> or C-33 <RH drive vehicles> and intermediate connector C-124
  • Ignition switch connector C-307
Check the connectors, for loose, corroded or damaged terminals, or terminals pushed back in the connector.

Q. Is the check result normal?

An open or short circuit may be present in the power supply line to the ABS-ECU. Repair the wiring harness between ABS-ECU connector A-03 terminal 20 and ignition switch connector C-307 terminal 2. Then go to Step 8.

Repair or replace the damaged component(s). Then go to Step 8.

STEP 7. 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.

Q. Is code No.C1860 or C1861 set?

Replace the hydraulic unit (integrated with ABS-ECU). Then go to Step 8.

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 Malfunction .

STEP 8. 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.

Q. Is code No.C1860 or C1861 set?

Go to Step 1.

The procedure is complete.