Thread: OBD2 works with the car off not on?

There's a simple solution I have for you... sell the Sonata and get the i30

Other than that I've got nothing to add.

Just a few things:
Is the laptop powered from the car's electrical system? If so, you may have a ground loop that can have issues for USB adapters. Run the laptop on battery or powered from a separate source.
I use AutoEnginuity and they posted this as an issue with their USB scan tool.
Good luck,
DNR

Yah, wait until the car is started before plugging in the OBDII cable and run laptop off of battery power, then report back.

Originally Posted by Curiosity

The ELM device's USB interface is disconnecting from the PC. That has nothing to do with OBD-II compliance or anything. Have you tried plugging the OBD-II port in after the car is running? I'm still thinking it's power related. If that works, then the voltage drop durring crank locks it up.

Yeah I gave that a go already as per my previous post, started the car and then plugged it in and it often comes up USB device not detected:

Originally Posted by yorky

EDIT: Oh and something I noticed, if the car is running and I unplug and re-plug the USB interface it sometimes comes up USB device not detected. Which is why I thought the device was just crap but yeah like I said no issue/error with the i30.

Originally Posted by dnr250

Just a few things:
Is the laptop powered from the car's electrical system? If so, you may have a ground loop that can have issues for USB adapters. Run the laptop on battery or powered from a separate source.
I use AutoEnginuity and they posted this as an issue with their USB scan tool.
Good luck,
DNR

Yep I tried two different laptops, firstly one running off laptop battery, then one running off the car, same result on both

Try a different Car and see what happens. When I had the cheapy OBD2, all the data lights would come on, but when the car was on it never worked. One day the whole unit stopped working. I kept getting a USB malfunction message from the PC.

Yes as stated I tried it on an i30, worked fine

Originally Posted by yorky

Yes as stated I tried it on an i30, worked fine

I missed that, my bad. I dont know if such a thing exists, but maybe you can have the ECU flashed. On my truck if I buy a reprogrammer I can flash the ECU. Maybe they have something like that for the Sonata? If you take the car to a Hyandai dealer, maybe they can flash it for you, like do a firmware update?

Example is the firmware update for my truck, changes how the transmission shifts, adds more MPG, more HP and more torque.

OK, thought you only disconnected the USB side and not the OBD-II side which would reset the ELM. It's not the ECU. Well that could still be a possible problem, but the ELM device actually stops functioning. It's not giving an error that it can't communicate with the PCM because it's dead as a doornail, kaput, tits up, going into the light...

It's not a 24V system is it? I still think it's something with overvoltage.

Yeah I disconnected and reconnected both the ELM and USB sides when running to reset it all.

12V system

I do have a lot of 'other' equipment in the car (radios, scanners, the car PC etc etc) but its all off during testing and disconnected from power.