Code No.C1861: ABS/Active stability control system-ECU power supply voltage too low




OPERATION


The ABS-ECU is energized by the ignition switch (IG1) through multi-purpose fuse 40 and the ABS-ECU terminal 20.

DIAGNOSIS CODE SET CONDITIONS


If the vehicle speed exceeds 6 km/h when the battery voltage is 7.6 V or less, the ECU will illuminate the charge warning light and set this diagnosis code.
note If the battery voltage is less than 9.6 V or 9.3 V (while the ABS is activating), the ECU will illuminate the charge warning lamp, but will not set diagnosis code C1861. If the vehicle speed does not exceed 6 km/h when the battery voltage is 7.6 V or less, the ECU will illuminate the charge warning lamp, but will not set diagnosis code C1861.

PROBABLE CAUSES



DIAGNOSIS PROCEDURE

STEP 1. Check the battery and charging system.
Check the battery and charging system.

  • Ignition switch: ON
  • Engine: Start
  • Engine speed: Approximately 2500 rpm
Measure the voltage between the battery terminals.
OK: 16 V or less

Q. Is the check result normal?
Go to Step 2.
Inspection, repair or replace the charging system component(s).

STEP 2. Check the ACS-ECU connector A-05.

Check the connectors, for loose, corroded or damaged terminals, or terminals pushed back in the connector.

Q. Is the check result normal?

Go to Step 3.

Repair or replace the damaged component(s). Refer to GROUP 00, How to Use Troubleshooting/Inspection Service Points - Connector Inspection Service Points .

STEP 3. Voltage measurement at ABS-ECU connector A-05.

(1)Disconnect the connector A-05, and connect special tool ABS Check Harness (MB991951) to the wiring harness-side connector.
note Connect special tool ABS Check Harness (MB991951) to the ABS-ECU.
(2)Turn the ignition switch to the "ON" position.
(3)Start the engine.
(4)Measure the voltage between terminal 20 and earth.
OK: 10 V or more

Q. Is the check result normal?

Go to Step 5.

Go to Step 4.

STEP 4. Check the harness wire between the ABS-ECU connector A-05 terminal 20 and ignition switch (IG1).





note After inspecting connector B-229 and B-210, inspect the wire. If connector B-229 or B-210 is damaged, repair or replace it.

Q. Is the harness wire between the ABS-ECU connector A-05 terminal 20 and ignition switch (IG1) damaged?

Repair the harness wire and then go to Step 5.

Go to Step 5.

STEP 5. Resistance measurement at ABS-ECU connector A-05.

(1)Disconnect the connector A-05, and connect special tool ABS Check Harness (MB991951) to the wiring harness-side connector.
note Do not connect special tool ABS Check Harness (MB991951) to the ABS-ECU.
(2)Measure the resistance between terminal 23 and earth.
OK: 5 Ω or less

Q. Is the result normal?

Go to Step 7.

Go to Step 6.

STEP 6. Check the harness wire between the ABS-ECU connector A-05 terminal 23 and body earth.

Q. Is the harness wire between the ABS-ECU connector A-05 terminal 23 and body earth damaged?

Repair the harness wire and then go to Step 7.

Go to Step 7.

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)Drive the vehicle at 6 km/h or more.
(6)Check if the diagnosis code is set.
(7)Turn the ignition switch to the "LOCK" (OFF) position.
(8)Disconnect M.U.T.-III.

Q. Is code No.C1861 set?

Replace the hydraulic unit (integrated with ABS-ECU) (Refer to ).

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