Same fuse keeps blowing!
 

'92 325i- The 5 amp fuse controlling the power locks and power windows keeps blowing. I'm replacing it about every other day now! (sometimes it mysteriously blows in the night as the car is parked! All worked fine when first parked, then it's blown in the morning!)

Would it be OK to put in a 10 amp fuse and see if it stops blowing?

Anyone have any idea of what to check or what the problem might be?

thanks much!

Indiana Randy

No. If you replace the fuse with one twice as large, then something else will blow. If you're lucky, it will be one of the electrical motors or switches. If you're unlucky, it will be a wire. Which can overheat and start an electrical fire...

Find the short, and fix it.

--DD

the fuses are there for a reason, do NOT put in a 10 amp fuse, disconnect one window switch at the time, and trace the fault, or your car might go up in flames

Thanks for your feedback. Time to read my manual and start one window/door lock at a time.

Yeah, from the voice of experience, you don't want to be upping the fuse rating of a circuit that keeps blowing. As a teen I had a problem with a fuse blowing in my Chevelle. I upped the fuse rating since the other fuse just popped every once in a while. In doing that, I shorted out and melted my entire turn signal harness and mechanism... melted it all together. Dumb, dumb, dumb thing for me to do (and expensive). To finish the story, I replaced the harness, but was still popping fuses off and on. It would pop the fuse every 15 or 20 times of hitting the brakes. So, I bypassed the brake switch with a long lead wire and then to a momentary push button switch. I ran the lead back out to where I could get back behind the car, then I pressed the switch. Both brake lights came on... then I cycled it... off, on, off, on... and the lights came on and off accordingly. Well, until the 20th press of the button, and then one brake light came on, the other one didn't, and the switch got hot. So there it was... a freakin' bastard bulb that worked most of the time but would sporadically short internally and pop my fuse. I changed out the bulb, smashed the bad one because it ended up costing me $100 in parts and labor, and never had a problem again.

So, in short, you probably don't want to be upping the fuse rating on the circuit, and good luck to you in tracking down the gremin in your system. It sounds like something similar to my light bulb... a part that works some of the time, then decides to short at other times and pop your fuse. Those are a nightmare to find because they are not completely broken, and at the time you test it, it may test out okay. All I can suggest is to cycle the load on the parts you are testing to make sure they function properly again and again.

Good luck and happy hunting! SmileWavy

Thanks for the input. As I see it, there is a problem with either one of the 5 window motors (one's a sunroof) or one of the 4 door lock motors.

Since it appears to blow on it's own in the middle of the night, I suspect it must be with a power lock motor. Reasoning is that's the last thing done as you leave the car. Maybe the power locks actually worked enough to get the doors locked, then blew the fuse, making it appear as though it popped in the middle of the night.

Does this make sense?

Yeah, that sounds like good solid reasoning. Hard to believe there could be trace voltage popping the fuse in the middle of the night, and an actuation of the door locks, being the last surge of power, could likely be the culprit. Now, I think these are solendoids that actuate the door locks, and that would mean they are just electromagnets. The actuators should look similar to this unit>
http://forums.pelicanparts.com/uploa...1118683117.jpg

The best way to check for a short on these is to check each one for resistance across the terminals using an Ohm-meter (a setting on a multi-meter). If one has resistance excessively low, then that could be the culprit (I don't know what the expected resistance should be, but they all should be about the same). If one is different than the others, then leave that one unplugged and see if the fuse stops blowing. If so, then you've found the problem.

Excellent! thanks much for the advice! I'll keep you posted. Really appreciate your help! thanks again!