Electrical Theory help ASAP!!

[kridgley]

Hi.
First, i think this site is awesome, you all always seen to head me in the right direction.
Second, the problem:
I have a 75, a light went out behind the guages ... i replaced all bulbs. not bad ... but when i tried them, they came on, then went off ,,along with the tail lights. So this morning i checked out the fuses ... tail light and intrument lght dead ... replaced them, they blew again.
Now by basic electrical thery, i would say that there is a short somewhere, but where to look. ....
I was thinking about it today, when i wanted to cross my conclusion with you all.. I was thinking that since the tail lights and instrument lights both come on with one switch ... maybe there is a short in the headlight switch? Everything else works ... the only thing that does not is the gas/bat./tach/speedo/oil/clock/temp ....all othe light buzzers etc work.
-my question for you all, is am i right in the switch, and how complex is the switch (price/availablility and fuction/location)

Any help will be greatly appreciated.

Thank.s, Kev

 

[Bob Chadwick]

Kev,

Sounds like you have a short somewhere from the switch upstream. The reason I say that is that when you turn on the switch, electricity goes past the switch and grounds out.

I got my switch at The Last Detail. Not too bad if I remember correctly. The dimmer part of the switch can go bad, which would probably do what you are describing.

Bob

 

[wishuwerehere82]

Kev,

You may go through a few fuses this way, but unplug all of the bulbs from that circuit and see if it is still blowing the fuse. Then put them back in one at a time until you find the problem. Same with the dash bulbs. If it's blowing with all the bulbs out, them you have a short somewhere in the wiring harness.
When you replaced the dash lights, did you get the exact same bulbs that came out? If they are a different wattage they will draw more current than the old ones.

Pete.

 

[kridgley]

only one or two were out (the fuel and bat) ... i then took all of them out, replaced them with what was listed in the owners manual ... now none of them will light, not even the speedo/tach .... not sure if the int fuse blows Iits size ... hard to see) , but the tail light fuse blew when i replaced it.


...what type of tests should i run, or what should i look for?

 

[wishuwerehere82]

If it was me, I would backtrack and redo all of the dashboard work that you did. There must be a connection that is touching a ground if it wasn't doing it before you took it apart. Check to make sure your bayonet connections on the light bulbs are in straight and all of the surrounding connections don't have something touching them without any pinched wires.

 

[lone73]

I have to agree with Pete, Sounds like the last thing you did induced a new problem. I believe all the dash lights are gray and just a single wire going into the back of each bulb socket. They are hot and ground to the metal base of the instrument such as the tach and speedometer.

Assuming it's a pinched hot wire somewhere I'd try this: disconnect and tilt out the center cluster and left dash, then put more fuses in and turn on the lights. If the wire is pinched it may become ungrounded as a result of disconnecting the two clusters from the dash. It should be a bit simpler then to find the cause of the trouble. Check the wires thoroughly for binding or bare spots then try to reassemble it to and keep an eye on the fuses.

good luck
.
.
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[titan81]

The switch is okay, no short there, if there was it wont work period
Your system is sending too much current through to the lights. You
either have 1. Current being drawn by a fault wire/wiring, or 2. Dont have a good ground connection causing spurts in ampirage. Those are my 2 guesses.

 

[kridgley]

FOUND IT!!
well, a while ago, had to take time to go to carlisle. It was a 'rigged' wire from the headlight switch to the wiper switch light ..... WHAT AN IDIOT ---- who would put that there ... any way, that was causing the short in the circuit off the headlight switch ... NO MORE PROBLEMS!!!!

Thanks guys