still blowing fuses

[jim coulter]

If you remember I was blowing the 10 amp tail fuse on my 84. replaced inside rear bulbs. couldn't reach outside ones. did have a loose wire on one inside one. fixed it. replaced all the front ones while I was at it, all worked good. hit bump, blew fuse. replaced fuse and the two right front parking lights dont work. found loose ground on front one. removed bulb and ground (it actually kinda feel out, connector had broken rubber seal only thing barely holding on) drove for a week no blown fuse. today, fuse blows at the very same spot (uneven pavement). Now I notice after replacing the fuse the amber side marker is actually, only barely glowing. Have 12.85 volts on brown wire, but my schematic shows brown(hot)and black ground(but its actually a brown and blue. That blue(which I believe is for the turn signal) must complete the circuit on the brown somehow for the bulb to light, so somewhere it seems to be "lacking" in its appointed duty. Where does the blue wire go and could whatever it goes to be bad, and shorting out at that point. I have "schematics" but I use that term loosely since its not wired exactly like it shows. any help will be g-r-e-a-t-l-y appreciated. going back outside, but I'll leave the light on

 

[Robertwav1]

If your blowing a fuse you definitely have a positive wire comming in contact with ground somewhere. Try not to let the dim lights throw you off....this is probably a dirty or loose ground. On the other hand it could be an indication that a hot wire is touching at times, this would explain the "going over a bump and fuse blows" scenerio. Chances are you have a bad wire, hidden from you i.e. along side the frame of the car...under rocker panels or seat etc. Intermittent electrical problems are the toughest to conquer, but persistence is the key. Use a meter to find out what's hot and what's ground, don't rely on wire colors, they can be wrong. Hope this helps...!

 

[vigman]

The Brown is HOT from the lighting switch

BTW Brown is HOT for ALL exterior lights ( not including main headlights).

Remind me .. which fuse is BLOWING?

Vig!

 

[vigman]

Oh the TAIL fuse

This ones a doosy!

You have all the headlight relays
All exterior lighting
The instrument cluster and all the interior dash lighting.
The audio alarm module ( Ding -Ding the doors open)
Fog light switch
Wiper washer switch assy lighting ( on door )
Tranny position light ( If auto )

So do you have an after market stereo?

BTW the fuse SHOULD be a 10 amp.

I would start inspecting the headlight relays ( weak spot )

I wish I had a remote video cam.. to look at it and give ya a better clue...but it will entail a point by point inspection.

Do both the turn signals flash at the same rate?

Do the emergency flashers work?

The TAIL fuse powers the turn /hazard switch as well.


Good luck

Vig!

 

[vigman]

AND

If you have an aftermarket stereo.... and it was "PROFESSIONALLY"installed..
you might want to remove it & check out the rats nest behind the dash.


Vig!

 

[jim coulter]

I figured out the wiring on front. The brown is hot to the side marker, leaves on blue-which goes to the front marker, goes thru that bulb and then to ground. So when the front parking bulb is removed the side should not work(no path to ground-thats the way the left side works)sooooo, since the right side marker "glows" when the front bulb is removed (no longer a path to ground) it seems its going to gound(not directly when it glows, but "trickling") on the blue wire. I'm figuring the blue is not directly grounded, but somewhere its close to grounding and then when you hit a bump, "pop" it goes to ground. I notice that while I was taking all the wiring out if the harness on the front right side, the side bulb quite glowing(and I had not put the front bulb back in yet) Right now while all the wires are laying loose in there, it seems to work like the left one. Went to work the next day and no 10 amp tail fuse blow.(Of course I made it a week when I changed the lamps before it surfaced again.)I haven't had a chance to get back on it in the last couple of days, but hopefully this week-end I can tackle it again. Oh, and I assume the stereo is the factory one, it matches the one in the manual that tells you how to set the clock and all. Thanks guys. Open to all suggestions.

 

[UKVette]

Remove all the bulbs from the lamps, put an ohm meter across the light feed and the earth, should read open circuit (if you leave any bulbs in, you will show the resistance in the filaments). If it doesn't show open circuit, unplug the loom to that lamp, if it goes to zero, then thats the line with the fault. If it shows open circuit to start with, have a pull and a shake on the loom to see if you get a resistance reading (a meter with an audible warning works best, you dont have to keep looking at it)

Also check your bulbs, if ones blown and the filament drops into the base, it could give you an intermittent short, had me in before now!

Rob.

 

[vigman]

Like I mentioned in the other post

( And UK Vette stated again )

Check all your bulbs & sockets.... sometimes if the bulb is the wrong type ( or the socket is distorted) and the bulb gets jammed into the socket, the two pins ( on a dual filament bulb ) at the base do not line up correctly and are just a HAIR away from shorting, increasing the load to the circut so the bulb will be visibly brighter.

OR

Look for bulbs that are starting to blacken inside, and are brighter as well.. we call em SUPER NOVA's since some of the filament has shorted together creating a lower resistance.

OR

the WRONG rating bulb.


Does the fuse have a big EXPLOSION look inside where the link failed? or is it just a little POOF Where just the link melted but no internal blackening.


Vig!

Still scratching my head on this.

 

[jim coulter]

I replaced all the bulbs but the two outside rear and forgot to get a spare tire bulb. I cant remove "all" the bulbs because I cannot physically reach the two outside rear (one left,one right) I do have a meter with an audible tone. And the fuses dont look black inside, just broken in one spot. Drove to work today and again nothing blew since seperating all the wires out in the front right harness. Going to get them out of the front left harness tomorrow, and work on the dash area Sunday. Thought maybe they were pinched where they pass in front of the radiator in that flat plastic wireway.

 

[vigman]

So it's a just a HAIR over current issue

When a fuse goes in a DEAD SHORT-HIGH CURRENT condition...it blacken inside... a clue, but not much help.


Vig!