CarPC starts up with ignition off when I exit my truck

KCarPC75 · 01-03-2008, 04:44 PM

I installed my CarPC about a week ago in my 2002 Dodge RAM 1500 front center console. Everything works great. It starts up when the ignition is turned on and shuts down when the ignition is off.

I've driven it for about three days now with no problems until today. I went out to the hardware store to get some parts to mount the LCD screen. I watched it shutdown when I left but it was back on when I got back about 30 minutes later.

When I got home I watched it shut down when I turned off the key. I sat there for about 2 minutes and it stayed off. As soon as I exited the truck I heard "BEEP" and it started back up.

I can reproduce over and over again. I even sat there for 10 minutes with it off and the same thing happened when I exited.

It has to be static electricity. It got very cold here over night and the static is terrible. If I get out very slowly, it doesn't happen.

I unplugged all the peripherals and even unplugged the ign/acc lead and left the 12V and Ground the only things connected and it still does it.

The 12V line is a 12 gauge wire coming directly from the battery. The Ground is bolted to the chassis under the dash. The ign/acc lead doesn't matter since it doesn't have to be attached for the problem to occur.

The power supply is an M2-ATX. I even tried another M2-ATX and it does the same thing.

If I put my multimeter on the acc/ign lead when the truck is off I get 0 volts but When I exit it jumps up several volts for a fraction of a second so it's somehow related to static.

Has anyone else had this happen? Any ideas what I can do to stop it?

Thanks!

Bugbyte · 01-03-2008, 07:15 PM

It is probably a USB device waking it up. A very common problem. Any activity on the USB bus will wake many PC's after going to sleep.

Sometimes the solution is to use a powered USB hub and cut the power wire on the cable that connects it to the PC so it does not draw from the PC when asleep.

KCarPC75 · 01-03-2008, 09:54 PM

I wish that was it but I remove all peripherals including the internal usb bluetooth device. I turned off all wake on entries in the bios as well.

I can reproduce this with nothing but the 12V and Ground wires attached with the carpc sitting on blocks of wood outside the truck as well.

I put my multimeter on the 12V and Ground. When I get out of the truck the volt meter goes off the scale. It's set at the 200VDC setting.

As a test, I sprayed static guard on the drivers seat and the transient voltage spikes barely measure now and the problem doesn't occur now. I then went to the passenger side which is not sprayed with static guard and sure enough it happens every time you get out.

Static guard is not a permanent solution.

Does anyone know of a simple way to suppress the static? I thought about putting another 12V regulated power supply in front of the M2-ATX but I was hoping there's something a little more simple.

SnyperBob · 01-04-2008, 07:26 AM

Would static straps work? They're ugly, but you asked for a simple way to fix the problem....

BiG K · 01-04-2008, 08:42 AM

yeh seconded, get a static strap BUT install it underneath the car somewhere in the middle so you cant see it

KCarPC75 · 01-04-2008, 11:58 AM

I think I might give the static strap a try.

I'm also going to build a 12V regulator with a surge suppression diode and put in front of the M2-ATX. That should stop the spikes from getting to the M2-ATX and it's very inexpensive. The voltage drop caused by the 12V regulator chip shouldn't be an issue since the M2-ATX can operate from 6 to 24 volts. I just need to test to see how many Amps I'm pulling.

KCarPC75 · 01-04-2008, 01:13 PM

Problem Solved!!

The Static Guard helped but I could still cause a startup every once in a while so I decided to try something different.

Apparently, the static was discharging through the metal under the power seat track. It must have been somehow pulling charge through the CarPC cables that were strapped to the wire harness under the seat.

I rerouted the CarPC cables through the wiring channel under the seat directly to the access hole I cut at the CarPC.

The CarPC cables are still sitting on metal that's attached to the driver's seat but the multimeter shows absolutely no voltage spikes now.

Now I need to see if I can cancel the order for the voltage regulator and surge suppressor diode!