So, you're saying that if you had one of the problems described in the
Stinger thread as a consequence of using a
tuning chip, (the situation I referred to in my post), all the burden would fall on them? How do you enforce their need to prove without taking on a burden of some sort? If they simply don't work on your car, the burden is on you to convince or compel them to do the work. You have to do something, like take them to court, to prove that you're entitled to service. And if you go to small claims, their mechanic is likely to be more credible than someone who isn't a mechanic and able to offer pretty convincing evidence if he/she can report damage that wouldn't happen under normal conditions. And the purchase contract may well specify that modifications alone, not consequent damage, is sufficient to void the warranty. I'd be pretty surprised if that weren't the case. Lawyers write these things and are pretty good at anticipating issues that they want to indemnify themselves against. And then, if something happens as a result of a mod, they're actually in the right. They didn't warranty a modified car, they warrantied the car as sold.
I'm not saying that this is the secenario that would routinely happen. It may never happen. But the notion that if it did, they would shoulder all the burden is questionable. People put chips in all the time and I don't think too many instances as I've described actually happen. But that doesn't mean that if they do, the owner can magically compel the dealer to fix the problem without assuming any burden or responsibility. And again, in such a situation, it actually would be the owner's fault, not the dealer's.
According to the law, the burden of proof is on the manufacturer to prove the damage was caused by an aftermarket device. It is known as the Magnuson-Moss Warranty Act.
Magnuson–Moss Warranty Act - Wikipedia
HOWEVER: (speaking as someone who has been on both sides of the issue, as a customer and as a dealership/corporate representative)
The dealership is not the manufacturer, the dealership will have a dealership employed warranty specialist. This persons job is to determine whether or not the manufacturer will reimburse the dealership for proposed warranty claims, if they feel there may be an issue getting paid back they can and will deny the warranty claim.
At that point it is up to the customer escalate to the manufacturers warranty department for review, sometimes the dealerships will do this for you, but in my experience that typically leads to the manufacturers area rep siding with the dealership, it is always better for the customer to make the contact and claim themselves.
If the manufacturer's rep decides that the claim has extenuating circumstances, they can deny it, and usually will, at that point the customer's first action according to 99% of car maker warranties: is arbitration, where in the manufacturer would need to provide proof that an aftermarket device caused the issue, so yes the burden of proof is on the manufacturer at this point. If the customer loses arbitration they can sue in civil court.
There are several factors that come into play, first, if the customer loses the arbitration, they are legally bound to pay the legal fees and arbitration fees incurred by the manufacturer, same if they lose the lawsuit.
The average cost to arbitrate a claim of this nature will likely outweigh the cost of the repair if not the cost of the vehicle, a lawsuit would be 2-3 times the cost of the vehicle. As such most people won't take it to the box, therefore the burden is now on the customer, because a manufacturer can legally decline a warranty claim and leave it to the customer to seek legal action to sort it out, and typically they don't because it is cost prohibitive for most people.
Now taking it from a customer perspective, I did take Chrysler to the box and sue them for a warranty issue, my lawsuit actually resulted in a full recall for 2005-2008 Chrysler 300 5.7L and 6.1L, and Dodge Magnum/Charger 5.7L and 6.1L vehicles. it cost me $29,000 in attorney fess which Chrysler had to pay, plus repair of my vehicle which amounted to $38,000. I had significant proof of a defect in the design of the motor, it was not modified, and it did not have any
tune or other aftermarket items directly related to the fail.
In the case of the
Stingers, the very first thing the dealer will look at is the
spark plugs, if they have been changed to colder
plugs, you bet your ass they will know the car was
tuned, because it is all over the forums about what is needed for these piggy back
tunes.. you can also bet your ass they will look at the forums and try to find any and all threads by the customer to see if there is any pattern of using aftermarket devices.