Horn, Turn Signal and HighBeam light problem on Mitsubishi

Vehicle details

Make: Mitsubishi
Model: Lancer ES
Year: 2006

The problem noticed by customer,Horn Honks non-stop and door locks are not working.

Turn Signal and High Beam light stays ON and will not Turn OFF.

These all problem starts after battery reset procedure.
Only negative terminal of battery was disconnecting for 15 minutes then reconnected.After that all these problem started.
The battery negative terminal was disconnected,because Check Engine Light Was ON.So just to Reset that Check Engine Light the Battery negative terminal was disconnected,for 15 minutes,then reconnected as before.These procedure reset the check engine light,but all these other problems started.


The troubleshooting details are as follows:-----


The confirm, one point answers in these types of cases are very difficult.There are multiple things that can cause such problems.

First check and confirm that no fuses are blown out in fuse box.
For Horn related issue try these:---

RESET HORN SETTINGS

Disconnect battery negative (black) terminal then reconnect it.
Use key to unlock drivers door twice, see if horn halts.

If no luck there:
Disconnect battery negative (black) terminal
Insert key into ignition and turn to ON
Reconnect battery

These procedure helps,if horn settings are got disabled.

But if its control module related issues or any other fault,then these procedure will not help.

Normally when we see the horn and lights stuck solid it is from a reverse connection on the battery or a voltage spike.... but just disconnecting and reconnecting the negative cable should not cause such problems.
So its definitely related to problem with module.

I will give more details:-----


The horn gets command by the horn-pad or through the keyless entry via ETACS module system on this vehicle... and the ETACS should pulse it if it were sounding the alarm, not a long honk.
But in your case its a loud honk and not a pulse.The horn is honking non-stop.

Recheck all fuses, did you pull them out and inspect or use a meter/test light to verify the metal tabs on top were all powered?It not,then please do it to confirm that fuse or its slots are not the cause of these problem.

Also without forget check the small yellow fuse holder in the under hood box? On some of such cases,the problem was noticed there.
To confirm issue and test fuse use a test light.Just probe both pins on the top of each fuse so that will confirm there is power on both sides.


But if all fuse and fuse slots checked ok. And if there is nothing found there and no success with the above troubleshooting procedure, then you will really need to get it in to a shop/dealer for deeper evaluation.
As I mentioned before, the horn can only be turned on with the horn-pad (or if the relay sticks of course) or via the ETACS as part of an alarm command.
If the horn is going off while locking the high beams and signals on, then this is clear malfunction in the ETACS as it should be pulsing them not solid. If the power supplies to the ETACS are good and the alarm cancel requests (key in door or reconnect with key on) do not help, ETACS diagnosis will be your next step. And for that professional Scan Tool is required.
A normal scan tool is of no use in such cases.



Because here the inspecting is for the ETACS module,a standard code reader would be of no benefit whatsoever.
Ideally a Mitsubishi MUT would be best as it has the most thorough access to the ETACS as well as SWS break out harnesses can be used as necessary, as the hands on investigation lengthens.
So that's the only option,to get into further troubleshooting.

These details will help.
Thanks.