brake light / hazard fuse keeps blowing

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movinon123

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Hey,

I just replaced my headlight switch and now I'm having problems with my brake light / hazard lights, the fuse keeps blowing. Ive noticed the fuse blow during 2 separate instances. The first one was while the truck was already running and the fuse already blown I replaced the fuse and checked the brake lights/ hazards while in park and they worked fine. Once I put the truck in gear it blew. The second time the truck was off and I replaced the fuse and the second I put the key in the ignition it blew. I put a larger fuse in (30a) in place of the 15a fuse thinking maybe the new headlight switch needed a higher amp fuse in that spot.

Whats not making any sense to me is before I replaced the headlight switch I had the turn signal switch replaced and everything was working fine.Theres clearly a short somewhere but i can't figure out where.

From the research I've done I know that the brake lights / hazard lights work through the turn signal switch but like I said before I replaced the headlight switch i was not having this problem

Any help would be greatly appreciated. 

Thanks

 

Seabronc

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You obviously have a short circuit, not sure if caused by your headlight problem or not.  Electrically the two should have nothing to do with each other.  By over fusing a circuit you are asking for an electrical fire.  The factory fuse size is chosen to prevent such a problem.  see the diagrams I posted for the headlight problem, http://broncozone.com/topic/25231-headlight-switch-help/#entry132386 

There are 4 different turn signal switches.  http://www.lmctruck.com/icatalog/fd/full.aspx?Page=2 If you put the wrong switch in it will ground out a circuit when the key is inserted.  I had the same problem because I had replaced the turn signal switch with the wrong one.

:)>-

 

miesk5

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Yo M.,

Pull the 30 amp fuse so worse things won't happen.

I assume a shop replaced the turn signal switch...

Read this.. I use a tablet so I can't edit the info I believe this "COULD BE" the short location...so look for this ****

Turn Signal Replacement in an 88; similar to 80-91; "...When I purchased my Bronco a few weeks ago the turn signal switch would not lock on a right turn. Minor annoyance is all, except for the fact that I'm also trying to teach two teenage boys how to drive. I'd rather they keep both hands on the wheel while turning a corner so I decided to spend the $35-40 to replace the switch. The neighborhood Autozone had it in stock, to my surprise so last weekend I undertook trying to replace it. You DO NOT have to disassemble your steering column to run the wire connector for the new switch. I wasted a good 3 hours trying to figure out how to disassemble my steering column when it wasn't necessary. I found a diagram in my Haynes that mentioned in a side note that you actually remove the connector from the wires. Wish I had found that a few hours ago. Step 1: Remove sterring wheel. - (Note: If there are no notches on the steering wheel and steering shaft to help you line them back up later, use a white grease pen to mark them.) This is a simple operation but you do need the right tools. on my '88 (with cruise) there are two screws holding the center cover of the steering wheel on and three wires. The wires are simple disconnects once you have the cover off, and you cannot put them back on the wrong way. Just take a second to look at them before you start yanking so you know where that one ground wire is supposed to hook up. Once you have the center cover off you need a steering wheel puller to get the wheel off the splines holding it to the steering shaft. Step 2: Remove the old switch. First find the switch connecter at the bottom end of the steering column. You can look at your new switch to see what it looks like, but it should be a gray connector with two rows of pins that is curved (crescent shaped?). Disconnect the connector. You can either disassemble the connector (see Step 3 below) or do what I did and cut it off. Don't cut it too short as you can still use it as a wiring guide in Step 3. The switch takes up almost the entire diameter of the steering column. There are two screws holding the switch down just to the left of center (under the switch locking cam arms). The switch arm itself screws into the switch mechanism so get yourself a small wrench or a crecent wrench to loosen it then unscrew it. There is one more ***** that holds a wire on the right side by the ignition. Keep this ***** and the two holding the switch down.Step 3: Install new switch. - This is where we get fancy. First, either draw a diagram of the connector on the new switch or compare it to your old switch to verify the wire colors are the same. We will be pulling all of the wires off the connector so you need to know how it goes back together. If you look at the face of the connector there is a piece of plastic that runs between the two sets of pins (mine was orange). You can pull this piece of plastic out by poking something small into the hole on the side of the connector (I used a multimeter probe) to pop it up enough to get your fingers on it. It pulls out pretty easily. Once you pull that piece out it is pretty simple to pull the wires out of the connector. You may need to use a small probe to loosen the prongs that hold the wires in, but without the center plastic piece this is very simple. Here's the hardest part of the whole operation. Tape the wire ends together to keep them from getting hung up (I used masking tape) then feed the wires back through the steering column.

**** There is a little metal loop about a third of the way down that the wires run through. It is a good idea to hit that loop as it helps keep the wires from rubbing in the wrong place. Getting the wires through the metal loop and also down the rest of the column is pretty tight.

****

It might be easier to use electrical tape on the wire ends and leave a long pigtail of it to help guide it. As soon as you can get a hold of the ends under the dash it makes it a little easier to pull it through. Using your earlier diagram or the old connector (with cut wires?) reinsert all of the wires into the connector and replace the center plastic piece to hold them all in. You might need the probe again for this piece as you have to make sure the little prastic prongs all end up on the correct side of the plastic piece or it will not hold in the wires. ***** the wire back down on the right side. The connect on the end of this wire had a small plastic cover to protect the connector as it is just a small piece of flat copper. Remove that cover and ***** the connector in place by the ignition. Then replace the switch itself and ***** those two screws under the cam arms. ***** the switch arm back in place. Connect the connector under the dash. Here's a tip. If your horn comes on while plugging this back in, you got your wiring diagram reversed. (Don't ask!) If all is quiet after connecting, this is a good time to test the switch. Step 4: Replace Steering Wheel: This is very simple. There is a notch on the steering wheel and a notch on the end of the shaft to help line it up (at least on my '88 there was). Alternately you hopefully marked it so you can line it back up. Once it is lined up and started on the splines of the shaft put the nut back on and ***** it down. I used my cordless drill-driver for this (with a socket adapter and a large socket). Then it just took about another half turn or so with the wrench to finish it off. Replace your wires, put the cover back on, and replace the two screws that hold the cover in place..."

Source: by Pukwudji

 
OP
OP
M

movinon123

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Question.... I know that the headlight switch gets a lot of power and thats why the plug has a tendency to melt when the headlight switch goes bad. which is why you have to remove the negative terminal from the battery before replacing it...

If I remove the negative terminal from the battery then remove the headlight switch can i then reconnect the battery and drive my truck.

Im still troubling shooting the brake fuse blowing and i really have a feeling it has something to do with this new headlight switch I put in.

 

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