Help.....blew the big fuse!

[alia176]

There we were driving on the Spearfish canyon hwy, enjoying the beautiful scenery that South Dakota has to offer, then all of a sudden blew the FL 30 amp fuse (lowest row, on the right side of the instrument fuse panel, pink color). Glad I brought the electrical manual This fuse powers up all power windows, seats, door locks and sunroof/moonroof controls. I was able to bypass the fuse and power up the window controller unit just so we can roll all windows up before the rain came. Here's what I've done so far at a rest stop. If you happen to have a manual handy, this might be easier to follow.

1) checked continuity between both of the spade terms of the fuse and ground. Yup, there's a short on one of the male term to ground. Compared this finding to the fuse right next to it, FL40 and there's no continuity between ground and either of the male spade term.
2) new fuse blew as soon as it was inserted. This tells me that the short exists before the Power Relay. Another words, we have a circuit that's always hot. The only thing that gets power from the FL 30 is the power door circuit. Makes sense - door locks work all of the time, regardless of the ignition circuit. I figure if I can figure out a way to disconnect BJ1 and BJ2 connectors to the door circuit then I'm in business. At least I'll have window control while I'm driving. Damn if I can find BJ2 connector Disconnecting BJ1 didn't remove the short.
3) just shiats and giggles, I checked the Power Relay and it's working fine. Incidentally, this relay and the defog relay are identical.

I'd love to hear some thoughts on this. I miss having the seat lumbar adjustment on this 4,000+ mile drive

Please email me at alia176@yahoo.com or call me at 312-286-4020 cell if there's something else I can try to fix this issue. We're hoping to reach Calgary, Canada by this late pm today (sunday).

Thanks.

Ali
'96 FZJ80

 

[kenton]

Hey Ali, I don't have the Electrical Wiring Diagram, so not much useful to say, just moral support. Sounds like your diagnosticating as well as I would (hell, better; I'd've forgotten my multimeter...). I'm not following your logic, but as you say, once I get the EWD maybe it would...

Ok, can't resist. Here's my thoughts: rarely (but sometimes) does a short occur just out of the blue (with no traceable cause). It is more often do to something you (or a family member) did accidently, rather than just a quirk of fate/cosmic ray. And it is even more rare that when a non-traceable, short-causing event does occur, that it results in a "strong" short, and not something (increasingly) intermittent.

What am I trying to say? That I think something actively happened: like, for example, someone in the back seat stuffed something hard under the driver seat, which broke a power seat wire and pushed it into the seat rail/grounded it.

Did anyone notice the moment the short occured, or is it just that someone tried to roll down a window and it didn't work? You may want to try manipulating all the controls on that circuit, and see if you can eliminate the short. Also, try hooking your multimeter up in ammeter/series mode, and see (momentarily) how much current the short is drawing (how resistive it is). If you've got a digital and not analog meter, it may not be as useful-- I've tried a headlight as a fuse before, to gauge how much current it draws.

A final thought: Have you recently done anything (service, repair, replace) to any of those circuits (sunroof, seats, windows)? I'd check those first, if you have.

Good luck,
Kenton

 

[RavenTai]

ouch that is not a good fuse to blow it has a lot of different circuits on it, one easy place to try is disconnecting the seats they should be accessible without disassembling anything.

 

[landtank]

I looked through the EWD and wasn't sure if I should call. If it were me I'd disconnect II2 and ID2 connectors and then check for a short. ID2 supplies the drivers seat and II2 supplies the passenger seat. If either one of these removes the short then you can move forward from there.

You might want to also consider the alarm as a potential problem. Not sure where it gets it's power from but considering some port monkey installed it I'd look closely for poor wiring there for a short to ground. Both my 80 and my wifes 4Runner suffered from these guys electrically.

 

[cruiserdan]

I know just enough about electricity to be dangerous . I do know that you can pick up replacement medium current fuses like that at most auto parts stores (Checker, AutoZone, NAPA ETC). I'll snoop through the EWD and see if anything jumps off the page at me.

 

[alia176]

Finally got internet connection up here in Calgary. Thanks a lot for the ideas. I'm figuring it's on a device that's always hot: seat controls or power door locks. I'll try to find BJ2 again tomorrow and see if that eliminates the short. Also, I'll disconnect the alarm system just to make sure. Can't explain why the Viper alarm system would create a short ckt condtion but who knows. The alarm still works normally.

Per Kenton's suggestion there might be some merit here. Couple of times we found the rear taigate door to be locked from the inside. We blamed the dog on this but maybe the rear lock motor was doing the funky chicken? I'll look at it tomorrow.


As Dan said, these fuses are quite common. I bought some extra ones in Wyoming somewhere.

BTW, anyone has a passenger rear mudflap they can spare? Mine seemed to have melted off somewhere between WI and Minnesota. Since then I've installed a properly angled tail pipe to direct the exhaust away!

Any 80 owners in Calgary area? I haven't seen any on the drive up here but did see a suite FJ45 off of Hwy 2.

Later,

Ali

ps it's 10 pm and still light out!

 

[alia176]

*****update*******

Found the short. It was in the passenger front seat connector, right above the heater. Two wires were pinched and shorted each other out. This is more likely my fault due to not placing the wires out of the way when I reinstalled the seat after I did some work.

Thanks all for the inputs.

Ali

 

[landtank]

Glad to hear it. Everytime I get one of these type failures I first look at what I've done in the past and then what the Port Monkeys have done. The factory work seems bomb proof for shorts to ground and electrical problems in general.

 

[hotsteppr7]

Hey man, same thing happened to my '93. As it turns out, the seat was shorting out the fusible link. Make sure there are no loose wires under the seat that are touching any bolts and grounding out your system. I know it's weird, but it's worth a shot. Also, take down the door panel and make sure the door or window switches didn't go bad and is causing the problem. I hope you got to your destination ok.