pupton

I am here because I am hoping someone smarter than me can help me understand what is happening in my truck's electrical system.

I have a 2010 F-150 Platinum that I bought new in June of 2011.

I have been having odd electrical issues.

I have a trailer hitch "Ford" light, and a cigarette 12v power adapter plugged in for a Go_Pro I use for a dash cam. It can also be used as a phone charger.

About 10 months ago I had a rear window go "boom" - from what I assume was some kind of problem with the rear window defroster.

I had the window replaced, and then noticed I also had an interior accessory light fuse (10A) blown. The drivers side overhead and mirror lights didn't work by manually activating them by pressing them. However, when I would open a door or use the interior light switch on the dash left hand side, they would still come on. I replaced that fuse, and a day later it was blown again. I let it go, since the lights still came on with the door open and also the switch on the dash left hand side.

Last week a rear turn signal light bulb went, replaced it and works fine now. (could be totally unrelated, just putting it here for info)

Yesterday I noticed the passenger side fuse must have blown as well. I went to NAPA and bought two fuses. The guy there said it could be the 12v power adapter causing issues...however, the power to that adapter is not affected. Even with this, the lights still came on when I get in and out of the car, and also when using the switch on the dash.

This morning, the lights don't come on at all when I use the switch or when I open the door.

There is something very wrong here, right? Before I pay a mechanic, any ideas? Please help. Any advice is greatly appreciated!

~Peter

Martian

What was the fuse number?

pupton

Thanks for the reply. Unfortunately, I'm at work now and will have to get back to you when I can get into my truck and check it. There are more than one now...since I have had 3 different varieties of failures for the interior lights.

pupton

I replaced fuse 25 and all interior lights now functioning normally. We will see how long it lasts.

I am very curious if what the NAPA guy said is true about leaving a cigarette lighter power adapter in long-term can result in unexpected electrical issues...

I am also very curious how a fuse can go and still leave partial functionality on the circuit that goes over a spam of weeks/months.

The last 10A fuse I (the one I just replaced this morning) looked thin (the actual metal inside) compared to the replacement I just put in.

Anyway, thanks for any ideas you have. I am also going to borrow my father in law's diagnostic box and see if I can plug that in and get any failure codes from the computer. (Unless you guys think doing that is a bad idea)

pupton

Fuse 25 keeps going out again. Fuse blows immediately upon insertion. Suspect a short. Another poster said he found someone had screwed into the passenger side visor light wire...will have to look at those wires.

4Stroke

Your best bet would be to get a wiring diagram for your truck or maybe someone here can post the relevant drawings. Fuse blowing right away is either a short to ground on the power side wiring, component in that circuit shorted or a plug-in accessory if applicable is shorted internally. Some components are activated for different functions and have more than one power source.

pupton

Based on what I have seen I suspect it is the first one (short to ground on power side wiring) but I am just a regular guy, not a mechanic/expert. I am thinking I could start by unscrewing the sun visor(s) and having a look. Maybe I should examine the dome light and map lights before I start unscrewing things? Are there any tools that can be used to help people located a short?

4Stroke

I'm not a mechanic nor an expert, just trying to learn, so I can hopefully fix my own vehicle and possibly help others.

If your electrical issues started after the window replacement, without a wiring diagram I'd probably start there, somewhere. Maybe a wire got pinched during the installation and over time the insulation wore off and is now in contact with metal? But, without a diagram it's just a guess, I have no idea if your past window issue and current fuse blowing problem have anything in common or not.

pupton

That's a good point. However, the lights were acting up before they actually replaced the window. I don't think the root cause can be from the rear window replacement. I'm also pretty sure the rear window defrost is a separate circuit from the interior demand lights. I might have to take it to a shop and have them run a few tests. I have seen guys use multimeters and tone generators to help located shorts. Scotty Kilmer (I think that's his name) uses a tone generator to pinpoint the location of a short. Hoping I can do something like that. But for a little more $ I can have a pro look at the whole car for an hour...

4Stroke

Do you have an overhead console in your truck?