SAE J-2534 standards

I have heard about J-2534 standards that allow aftermarket devices to interact with factory OBDII ECMs.
Just hoping someone could shed some light on this topic. I have only just heard about it, but it seems promising...

What are you asking about specifically? The J2534 pass-through devices allow you to connect to a manufacturer's website and for a smll fee you can program a controller with a stock calibration. The process does not allow for "tuning" as we do it.

Dammit. Just wondering about it. I thought it might be cool. I should have known better. Ha!
I was just thinking that I could get around swapping ECMs and flash the cal I needed.
Oh well...

Thank you sir! You are a wealth of knowledge!

That standard mandates the OEMs to give the ability to reflash ecus and other modules without using dealer tools.
This means you can buy a compliant aftermarket box and cable and use dealer-provided software to download calibrations and flash the ecu and modules.
you will not be able to save/modify the calibration binaries, only flash them.
Depending on the box you buy, it may have other tools as key programming, change module settings (locks, windows and general behavior).

I have used a few to flash stock calibrations to new and used controllers and to update the calibration on some problematic vehicles we don't have tuning support. I have also programmed new instrument clusters on Ford vehicles and updated the odometer reading to match current mileage.

You need to pay a subscription to use the software, it's not free (very expensive indeed)

Before you buy anything first check if it is supported by the OEM

Thank you very much! I can't afford very expensive though. LOL!
I was just hoping that this standard would allow some kind of back door to allow tuning on ECMs that were not hackable before.

Thanks again!

Not really. It was designed by SAE which has input from OEM. It's not intended to allow unauthorized access to cal details, only to allow non-dealer installation of oem supplied updates.

Don't feel bad. I got excited when I first heard about it, too.

It is a good thing, in theory. The standard is documented and anyone could write software talking that protocol which can use any J2543 cable. There are various cables available that can be used - in the OEM and aftermarket - and varying levels of cheap too. Unfortunately though its a complicated protocol and nobody that I am aware of in the aftermarket uses it even though they could if they had enough time to implement. There is cheap hardware around with partial implementations eg the x-horse toyota clones "toyota mini vci" which work only with toyota tis techstream and very slowly. Then theres the GM MDI interface which is a great implementation but costly for genuine. But if your OK with clones, they exist. Then in the mid range there are interfaces like the drewtech mongoose pro. They are a good genuine implementation and come in at just under half the price of a genuine MDI. The drewtech and MDIs will work with the OEM tools from multiple manufacturers including the pc based tech2 emulator tech2win. Just beware that that mongoose does not support the ALDL protocol if your doing older GM work. In theory the idea is smaller shops can have 1 expensive cable and then lease the OEM software from multiple manufacturers for short periods to upgrade factory calibrations or tweak settings on a car by car basis without breaking the bank. I have a 'GM' MDI and have tested that the toyota techstream sees it and lists it as an option to use. But I dont have any toyotas to test (or really care for them).