Fuses detonate, wiring help needed

[Heetseeker_1]

While wiring in some simple back-up lights, I seemed to have blown some fuses in the engine compartment. The truck wont start, no lights, no nothing. I have traced the fuse to the 50amp ignition/run/ac and a couple more are tadered. I cant figure out how the heck it happened, so if you electrical whiz bangs want to take a crack at it, go right ahead. I'll get more fuses at the parts store tomorrow. $$$$$ ( the thingy on the bottom is the relay)

 

[Heetseeker_1]

by the way

The switches light up when on, and i'm thinking now that I might have sent 12v back through my tc lock up switch when I hooked it up next to the back up lights.

 

[paccool]

Make sure that you are not grounding your switched supply at the switch. Disconnect the switched supply to see if things return to normal. If not, There is a circut breaker on the inner fender that may have gone bad. The relay will not cause a fuse to blow unless it's hooked up wrong.

 

[Howard Durand]

To cause that much damage, the 8 gauge circuit to the light relay must be grounded somewhere.

For it to include fuses in other circuits, it must have also involved them in the same short.

I would suspect the relay since two separate 12v. circuits and a ground come together at that point. It could have failed and flashed over to ground internally and at the same time grounded the other circuit.

Check it out with an ohm meter.

 

[Heetseeker_1]

12volt follies

Stan,



thanks for the input. I'll look at the mess i've made this morning and try to figure it out again. When you say not to ground the switched supply at the switch, do you mean to insulate the connector? Right now, I have 12v (switched) from the fuse box to the switch, ground from switch to body metal, and the other post to the supply (Relay)



On another note, my TC lock up switch (which activates when grounded, I think) needed 12v to the switch to light it up when in use. I tapped into the 12v switched supply to the back up lights and may have plugged into the wrong post on the switch. I'll have to get into it this morning after I have some more coffee. Thanks a ton for the reply.



Steve.

 

[Heetseeker_1]

Howard, I'll check that out too. So many possibilities with this 12v stuff. I just may have to get a book on it. I just absolutely suck at this wiring crap. For a guy who tends to just get a bigger hammer to finish the job, this is ... ahem... most frustrating.



Steve.

 

[paccool]

Well, did you find the problem? Sounds like something simple is messing you up.



Where is Wilton located/ I travel all over and can't place it. If you can't get it straightened out, I could come by when next in the area if it would help.



Stan

 

[Howard Durand]

Heetseeker_1



When electrical problems arise they can usually be traced directly back to whatever it was you did just before everything went in the toilet.



Did it happen when you switched it on? If so, I would really suspect the relay.



The 12 volt circuit from the switch to the relay would normally be isolated from the 12 volt circuit that feeds the lights.

The light circuit passes through the relay contacts but should not come in contact with the switching circuit.

If I understand what you said, that fuses blew both in the circuit feeding the lights as well as the circuit the switch is connected to,

then the relay would be about the only place they would be close enough together for them both to be involved in a short.



Even if the relay is not the problem, don't let all of those fuses blowing scare you. Just disconnect all of the new wiring that you just installed then replace and test each fuse that blew.

If your system can be returned to normal with your new light circuits disconnected, carefully check out all of your wiring and the devices you installed before the trouble started.

If you don't find anything wrong, replace the fuse to the switching circuit and close the switch. If nothing happens, open the switch and re connect the switching circuit to the relay.

Close the switch again and see if the relay picks up. If it does, open the switch and reconnect the light circuit wiring then replace the fuse to the light circuit with a much smaller fuse.

If that doesn't blow when you put it in, close the switch to energize the light circuit. (Remove the bulbs first so that you are only testing the wiring).

By this time, you should have everything working or have located the fault.



This may or may not be of any help with your problem but if you just keep cool and think about it, you can probably figure it out.



Best of luck,



P. S. I don't see anything wrong with your wiring if you hooked it up according to the diagram you provided.

 

[Heetseeker_1]

Deep breath....exhale...one more time

Stan,



Nope, didn't get if figured out yet. I had to work yesterday (24hrs at the firehouse and ran all day) so I wasn't able to get into it. Also, before I do try again I am going to need more of the 50amp cartridge fuses that blow up every time I hook up the 12v unswitched hot to the relay and turn on the ignition. They are $2. 50 each and I used 3 so far. The parts house won't get them in until Friday, and i'm leaving on a camping trip that morning and wont be back until monday morning early.



Wilton is South of Elk Grove wich is South of Sacramento. I live about 7 miles east of Hwy 99 on Arno rd, just East of Alta Mesa Rd. It's out in the country a bit, but I love not having neighbors looking over the fence at me or the crime that's normaly in the city areas. And, I built a shop that is larger than my house! (2100sq ft) Can't do that in the city...



Howard,



Thank you for your very discriptive troubleshooting advice. I will print it and use it when I get some more fuses next week. I needed a little space from the project because it was stressing me out. I hate not being able to fix things. I got a lesson in relay construction and funtion this morning when I got off work by an old crusty Apparatus Engineer, who has been real helpful in the past when I have questions. I will kick back this weekend and have another go at it on Monday.



Thanks again for the help... You guys are great.



Steve.

 

[DennyDay]

Heetseeker:



One of your problems my be the relay at the bottom of the drawing. If it isn't now it will be later. It appears to be a horn relay, takes alot of juice to operate and is not for continous duty, intermitant only.

Denny