Inspection Procedure I-1: Only specific function(s) works (fail-safe state).

caution

Whenever the ECU is replaced, ensure that the input and output signal circuits are normal.

COMMENTS ON TROUBLE SYMPTOM

If the voltage at the ETACS-ECU is excessively lower or higher than system voltage, the ETACS-ECU sets diagnosis code No.B1728 and B1729 and enters the fail-safe mode. If the ETACS-ECU enters the fail-safe mode, only the following functions are activated.
The functions that the ETACS-ECU can use when the voltage is between 8 - 10 volts or between 16 - 18 volts

Headlamps (low-beam)
Tail lamps
Windshield wiper low-speed operation
Windshield wiper intermittent control
Turn-signal lamps
Hazard warning lamp
Buzzer
Door unlock
Room lamp
Daytime running lamp
Power window control
Engine fan control

The functions that the ETACS-ECU can use when the voltage is between 6 - 8 volts or between 18 - 24 volts

Ignition
CAN bus line
Immobilizer

The functions that the ETACS-ECU can use when the voltage is less than 6 volts

PROBABLE CAUSES

Malfunction of the ETACS-ECU
Malfunction of battery
Malfunction of alternator

DIAGNOSIS PROCEDURE

STEP 1. Power supply fuse check

Q. Is the fuse in good condition?

Go to Step 2.

The short circuit may be present in the power supply line. Check and repair the wiring harness, if necessary. And then replace the fuse. Go to Step 4.

STEP 2. Battery check

Refer to GROUP 54A - Battery Test

Q. Is the battery in good condition?

Go to Step 3.

Charge or replace the battery.

STEP 3. Charging system check

Refer to GROUP 16 - Charging System

Q. Is the charging system in good condition?

Go to Step 4.

Repair or replace the charging system component(s).

STEP 4. M.U.T.-III diagnosis code.

Check that ETACS-ECU sets a diagnosis code.

Q. Is the diagnosis code set?

Refer to diagnosis code chart

Replace the ETACS-ECU. Then perform the variant coding and write the VIN data (Refer to GROUP 00, Precautions Before Service - How to Perform Variant Coding