No. Voiding a warranty means that the machine is no longer under warranty. Denying a warranty claim is different.
Let's use your example, and assume that the unit was taken in and the owner did not tell them about the device. Or, what should have been done, disconnect the device before taking it in. That's not always possible if the skill level isn't there.
Tractor won't start. Tech troubleshoots for hours and has to bypass/ disconnect the device. Ultimate result is that the starter is failed. Starter replaced under warranty, additional troubleshooting time is billed to the owner. Easy peasy. Not rocket surgery.
Been there with my truck. It's tuned and has a small lift. The shop knows this but I always remind them. When the trans input seal started leaking they didn't say "well you tuned the truck". They fixed the leak. When the panhard (track) bar ball joint had play, they said "lower joint is aftermarket. We can replace the upper one but you need to bring us the lower one".
Yes, and I’ll give another example: I bought a new P/U and installed an additional camera which operates on a bluetooth frequency.
After a month‘s ownership the battery was dead after a weeklong vacation…returning to the airport the P/U battery was dead…would not start. Jumped it and it recharged the battery just fine.
Another period of a week sitting somewhere, it occurred again. I took it to the dealer and complained the battery was not holding a charge more than a few days.
They discovered the “hot” wire I used to install the aftermarket camera was the source of the battery-drain. How..?? Any stray bluetooth equipment (airport security cameras, nearby vehicles or cell phones operating on bluetooth) was “waking up” my camera and draining the battery.
The Dealer disconnected it from the “hot” wire source I’d selected to power the camera (an auxilliary cigarette-plug) and re-connected it to a source which was only “hot” when the key was inserted into the ignition. Problem solved…. but cost me $350 troubleshooting/re-wiring labor. My fault completely….therefore no “warranty” coverage.
However, other warranty items were always covered for the entire warranty period. (bad computer 2 months later, and speedometer/cruise-control errors requiring new instrument cluster.)
Sooo…..just because I’d altered the OEM wiring didn’t by-itself void the warranty…. it only did not cover an electrical-drain caused by my improper installation. They (honestly) never made any effort to claim my aftermarket installation alteration of the electrical-system caused subsequent electrical issues with the instrument cluster.