I've noticed suddenly that when my car is on, and I put my foot on the brakes, my gauges (Boost, Voltage, Oil Pressure, water temp) dim/turn off. MY AFR gauge is unaffected. As soon as I am back in gear and driving, they turn back on. I came to a stop and tested it, sure enough, when not moving/ moving very slowly/parked, I can literally turn the gauges clusters on/off by hitting the brake pedal. If the car is OFF, but the gauges are illuminated (car is OFF, but key is in the ACC slot), pressing the brake does NOT affect the gauges. It is only with the engine running it has an issue.

** Not related, solved in later post **
Also, I pushed my clutch pedal in, and it didn’t fully come back up! I had to manually pull it up with the side of my foot which cause the car to stall out because I wasn’t quick enough. This hasn’t happened a second time (yet) and is not replicatable but I figured I’d mention it as well.

Friend said it sounds like the alternator, since with the key IN the car, but the car not ON, it does NOT happen. It only happens once the car has been started.

I hooked up a multimeter to my battery terminals, and with the car OFF, it read 12.3V.
As soon as I power on the car, it jumps up to 14.00V~

This leads me to believe it is NOT the alternator, but what the hell could have caused this/ where to start my diagnostics?


Here is a video of what is happening. You can see without the car started, the issue does NOT happen. Once I start the car, I wait a moment and then you can literally see when I am pushing the brake pedal.

 

What are the gauges wired into for power? Where are they grounded? What are the states of those connections?

Getting those answers is where I would start my diagnostics.

 

Yeah that is the plan for this evening. I can't think why the AFR isn't affected; it shares a cluster on top of my steering wheel. It must have a different power or ground source.
The clutch pedal thing happened again this afternoon while I was looking for symptoms with the cabling.
Odd, I can't see how the two would be related, but but *I believe* occurred on the same day and have never given me an issue before.

 

Clutch pedal issue was simply a leaking clutch line. Issue resolved by switching to a stainless steel STM clutch line.




Still trying to find source of issue with pressing the brake and the gauges dimming. Pulled all the gauges and checked wiring and grounds, everything looks fine. Still looking like it could be alternator, as I've noticed that my voltage isn't always right at 14. Somedays it's at 13, other days it's at 14.5, or 14.