Inspection Procedure 4: Vehicle power does not turn ON. (Not possible with power supply mode ON only)

caution Before replacing the ECU, ensure that the power supply circuit, the earth circuit and the communication circuit are normal.


If the vehicle power does not turn ON (not possible with power supply mode ON only), the possible cause may be that the OSS-ECU cannot output the IG1 signal, or that the IG1 internal relay of ETACS-ECU does not turn ON. Therefore, OSS-ECU or ETACS-ECU may have a problem.



STEP 1. M.U.T.-III diagnosis code

Check if the diagnosis code is set to OSS-ECU.

Q. Is the diagnosis code set?

Diagnose the OSS. Refer to .

Go to Step 2.

STEP 2. Voltage measurement at ETACS-ECU connector (IG1 terminal)

(1)With the ETACS-ECU connector kept connected, measure by backprobing.
(2)Using the M.U.T.-III, set the forced power supply output to "IG-ON".(Refer to .)
(3)Measure the voltage between the ETACS-ECU connector (IG1 terminal) and body earth.
OK: System voltage

Q. Is the check result normal?

Go to Step 3.

Replace the OSS-ECU and register the chassis number (Refer to ).

STEP 3. Check of the troubles

Check that the vehicle power (power supply mode ON) can be turned ON.

Q. Is the check result normal?

Intermittent malfunction is suspected (Refer to GROUP 00 - How to Use Troubleshooting/Inspection Service Points - How to Cope with Intermittent Malfunction ).

Carry out the troubleshooting relevant to the input signal of ETACS-ECU. (Refer to GROUP 54A - ETACS .)