P3Cars vent gauge help!!
 

Ok, so a little back story first.

I have installed a p3cars vent gauge, and for the most part it works great. Recently I installed a flex fuel kit, and I used one of the gauges aux inputs to read ethanol content. All seemed fine until I had the gauge unhooked from the OBDII port during flex fuel tuning so that I could plug in my ecutek cable. While monitoring ethanol content with my laptop in proecu, I noticed when I would turn my headlights on, my ethanol content would jump from e20 to e55!

I contacted P3Cars about the issue, and they told me that I was feeding too much voltage to the automatic dimmer switch and I had damaged the controller chip. They claim a maximum of 12V is safe. I was getting 14.4V.

They sent me a new chip, and I have since installed it. The gauge and ethanol signal are working great, but I still can't hook up the dimmer. I have checked every switched power source I can find that energizes with the parking lights. And I can't find a single source under 12V.

Can anybody tell me where to grab a 12V source that goes high with the parking lights?

Thanks.

check the traction control buttons near the shifter. i'd b shocked if they are more then 12v. otherwise u can actually manually dim that gauge by holding down a certain button

Wouldn't that be a constant 12v? I suppose I could pass it through a relay. I need a switched source (0V with headlights off, <12V with headlights on)

I was considering tapping the fuse panel under the dash at the "Panel" fuse and putting a voltage regulator in series to hold it at 12V. But I'm not sure how much current the gauge draws and I don't want it to get hot.

something is not right from P3Cars as the static voltage of the lead acid battery is 13.8 and charge voltage is often 14.4

14.4V is what I'm seeing almost everywhere in the car. I would have thought their hardware would be up to par with that voltage. But apparently anything over 12V through the dimmer wire is bad news for the controller chip.

I just received an email from them stating that they are replicating the issue and trying to find a fix. They also said that nobody has mentioned this issue to them before. Which I find interesting. But Honestly, if i hadn't been logging e% at the time, I may have missed it. Because the dimmer was actually working.

Im wondering if there is just some bypass problems when the gauge isn't powered on. the OBDII plug was unhooked at the time, so the gauge was powered down. But the dimmer wire, and ethanol signal wires were still hooked up.

the wire that controls lighting those buttons is switched. my footwells are tapped into it for power so that they only come on with parking lights/headlights