F430 Engine Mounts replaced (sucess) led to crazy cluster lights freakout.

Just posting in case this happens to someone else while changing engine mounts.

Soooo I changed the mounts yesterday without a problem (super easy) but when I first turned the car on to test drive it I was welcomed to the crazy "every module is pissed" light show. My first thought was it's a coincidence, and the battery must be weak, and finally gave out. Now I haven't had any other issues prior yesterday, and drove it the day before, it wasn't sitting.
I always default to basic troubleshooting and grabbed my multimeter to check voltage on the battery. To my suprice, it was 15V! This didn't make sense so I grabbed another voltmeter and confirmed the reading. I called in a friend that had lots of years of experience to catch up and ask for his thoughts. I've seen lots of batteries fail to keep voltage (capacity really) but never one that failed with high voltage. I got my scanner out and was getting left and right bank high voltage faults.

what the crap.

My buddy suggested I remove the engine ground strap, inspect it and if looks good, give it and it's bolts a good cleaning and reinstall it. I switched the power back on, and boom, no faults. I tested the voltage it's at 12.7V.

I called him back and told him the good news, and promised him a beer next time I saw him.

 

good guess, but no they were nice and tight. His theory, and it seems like he was correct was that since the engine mounts were completely broken, and the engine was sitting low and making contact with the frame somewhere, and reducing the resistance of the overall ground circuit and hiding an issue with the strap. When I removed the strap, I did notice oxidation on the frame contact point, and had to use a wirewheel to clean it up. He told me he ran into this exact scenario before after changing out motor mounts in other models of cars, which explained why it was the first think he suggested I look at.

After some thought I did remember some ghost faults while hard shifting on less than perfect roads. I wonder if the engine was bouncing around, breaking contact and causing voltage spikes.

Anyway, just wanted to post in case someone runs into this issue, I'm sure it's not common, but voltage drops and spikes plays havoc on PLCs, both in industrial and automotive equipment. I was shocked when I saw that 15V reading tbh, threw me for a loop.