C1860

DTC C1860: Abnormality in battery voltage (high voltage)
DTC C1861: Abnormality in battery voltage (low voltage)

CAUTION:
If there is any problem in the CAN bus lines, an incorrect diagnostic trouble code may be set. Prior to this diagnosis, diagnose the CAN bus lines.

CAUTION:
Whenever the ECU is replaced, ensure that the CAN bus lines are normal.

CAUTION:
When I replace hydraulic unit (integrated with TCL/ASC-ECU), Always perform the calibration of steering wheel sensor and yaw rate sensor.

CIRCUIT OPERATION

The TCL/ASC-ECU is energized by the ignition switch (IG1) through multi-purpose fuse No.2 and the TCL/ASC-ECU terminal 4.

TCL/ASC DTC SET CONDITIONS

C1860 will be set when the power supply voltage to the TCL/ASC-ECU became more than 18.0 ± 1.0 volts during a run in more than 12mph (20 km/h). C1861 will be set when the power supply voltage to the TCL/ASC-ECU became less than 9.7 ± 0.3 volts during a run in more than 12mph (20 km/h).

TROUBLESHOOTING HINTS (THE MOST LIKELY CAUSES FOR THESE DTCS ARE TO SET ARE:)

Current trouble

- Excessive electrical load
- Defective battery
- Damaged wiring harness or connector
- Malfunction of the hydraulic unit (integrated with TCL/ASC-ECU)
- Charging system failed

PAST TROUBLE

Carry out diagnosis with particular emphasis on connector(s) or wiring harness in the power supply circuit (terminal 4) to the TCL/ASC-ECU. For diagnosis procedures, refer to "How to cope with past trouble" How to Treat Past Trouble).

DIAGNOSIS

Required Special Tools:

- MB991958: Scan Tool (M.U.T.-III Sub Assembly)
- MB991824: Vehicle Communication Interface (V.C.I.)
- MB991827: M.U.T.-III USB Cable
- MB991910: M.U.T.-III Main Harness A
- MB991997: ASC Check Harness

STEP 1. Using scan tool MB991958, diagnose the CAN bus line.

CAUTION:
To prevent damage to scan tool MB991958, always turn the ignition switch to the "LOCK" (OFF) position before connecting or disconnecting scan tool MB991958.

(1)Connect scan tool MB991958 to the data link 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 CAN bus line found to be normal?

YES Go to Step 3.

NO Repair the CAN bus line CAN Bus Diagnostics Chart). Then go to Step 2.

STEP 2. Recheck for diagnostic trouble code.

CAUTION:
To prevent damage to scan tool MB991958, always turn the ignition switch to the "LOCK" (OFF) position before connecting or disconnecting scan tool MB991958.

(1)Turn the ignition switch to the "ON" position.
(2)Erase the DTC.
(3)Turn the ignition switch to the "LOCK" (OFF) position.
(4)Turn the ignition switch to the "ON" position.
(5)Check if the DTC is set.
(6)Turn the ignition switch to the "LOCK" (OFF) position.

Q. Is DTC C1860 or C1861 set?

YES Go to Step 3.

NO The procedure is complete.

STEP 3. Check the battery.

Check the battery Battery Test).

Q. Is the battery in good condition?

YES Go to Step 4.
NO Charge or replace the battery.
STEP 4. Check the charging system.

Check the charging system Initial Inspection and Diagnostic Overview).

Q. Is the charging system in good condition?

YES Go to Step 5.
NO Repair or replace the charging system component(s).
STEP 5. Measure the voltage at TCL/ASC-ECU connector A-38.

(1)Disconnect the connector A-38, and connect special tool MB991997 to the wiring harness-side connector.
NOTE:
Do not connect special tool MB991997 to the TCL/ASC-ECU.

(2)Turn the ignition switch to the "ON" position.
(3)Measure the voltage between terminal 4 and ground. It should be approximately 12 volts (battery positive voltage).

Q. Is the voltage approximately 12 volts (battery positive voltage)?

YES Go to Step 7.

NO Go to Step 6.

STEP 6. Check the following connectors.

- TCL/ASC-ECU connector A-38
- Junction block connectors C-202 and C-203
- Intermediate connector C-24
- Ignition switch connector C-308
Check the connectors, for loose, corroded or damaged terminals, or terminals pushed back in the connector.

Q. Are the connectors and terminals in good condition?

YES An open or short circuit may be present in the power supply line to the TCL/ASC-ECU. Repair the wiring harness between TCL/ASC-ECU connector A-38 terminal 4 and ignition switch connector C-308 terminal 4. Then go to Step 8.

NO Repair or replace the damaged component(s). Harness Connector Inspection. Then go to Step 8.

STEP 7. Recheck for diagnostic trouble code.

Check again if the DTC is set.
(1)Turn the ignition switch to the "ON" position.
(2)Erase the DTC.
(3)Turn the ignition switch to the "LOCK" (OFF) position.
(4)Turn the ignition switch to the "ON" position.
(5)Check if the DTC is set.
(6)Turn the ignition switch to the "LOCK" (OFF) position.

Q. Is DTC C1860 or C1861 set?

YES Replace the hydraulic unit (integrated with TCL/ASC-ECU). Then go to Step 8.

NO It can be assumed that this malfunction is intermittent. How to Cope With Intermittent Malfunctions.

STEP 8. Recheck for diagnostic trouble code.