40A window/sunroof fuse blowing

[oakback]

I've had my 100 for maybe 10 days, and this fuse has blown twice. I searched but didn't find any info, maybe my search skills suck.

I'm okay doing diy stuff (just swapped out a fuel injector, fixed misfire code), but I'm not too good at diagnosing electrical. I'd appreciate a starting point.

 

[TXLX100]

Does it break the fuse as soon as you install it, or is it when you operate the windows or sunroof? I'd check that first.

40 amp seems really high. Looks at your owners manual or a FSM (can download here probably) and see if that is the right fuse. Prior might have installed a bigger fuse because it was breaking. With electrical, you want to start isolating further and further until you find the problem. Was vehicle in accident? Start closely inspecting the doors, door jambs, door jambs near roof line, body panels, etc.

 

[oakback]

40a is what's on the fuse box cover.

It doesn't happen as I install it. The first time I got all the windows and sunroof open, then when I tried to close them nothing happened.

They worked fine for several days, I was sure to operate only one at a time (I thought maybe it blew because I pushed all the switches at once).

Second time it blew, I tried to open windows and nothing happened. So I'm not sure exactly when it's blowing.

Is the lumbar motor on the same fuse? I tried that shortly before the second blow. It went down but wouldn't go back up, at the time I figured the switch was dirty or the motor was tired. I can't remember if I had pushed that before the first blow. I guess I could replace it again and hit the lumbar button to see if it blows.

It hasn't been in any major accidents that I could tell, but definitely a few dings. Front bumper is cracked and there are a few dents. PO said he was selling it because his teen son kept hitting things with it.

 

[oakback]

Bought a couple extra fuses. Popped the first one in, tried each window and the sunroof. Then pushed the lumber adjustment button, and it blew.

I guess I need to get under the seat and look for a frayed wire of some sort, right? Is the best way to pull the trim pieces at the floor and unbolt it to get to that wiring?

 

[TXLX100]

If you suspect the lumbar motor, I'd unplug the seat at the main harness and give it a bit and see if it breaks the fuse again.... So you don't have to hunt all over. Are there any add-on accessories on in the car that someone may have tapped into? Definitely something going to ground.

 

[oakback]

Do you mean unplug it, and leave it like that for a day of use to see if it blows for some other reason? If so, that's gonna be tough, I had to slide the seat forward to unplug it, and I'm 6'4".

Nothing aftermarket at all, completely stock.