blown fuse

[jim coulter]

Driving to work today in my 84 with z-51 suspension, I hit a bump and all the dash lights went out. When I got to work I further discovered the running lights out also. Checked the fuse and the ten amp fuse was blown. Went to napa and bought some fuses hoping maybe that fuse was just old and about gone(although I cant see that happening, but you can wish, right). Put the new fuse in and everything worked. Coming home, hit another bump (an impossible task to avoid, since they figure working on every street at once makes more sense), but anyway, the fuse blew again. Obviously there is a short that is going to ground when the car gets jolted, but where? Has anyone had an experience like this, or know where would be a good place to start looking first. Probably wont be back on line till in the morning, hopefully I'll find some suggestions waiting for me. Thanks all.

 

[JonM]

Your best bet would be to get a wiring diagram then go hunting. You can get one by joining this site, http://www.crossfire.webhop.net/
Then clicking on TECH, then in the lower right hand corner of the list is "Wiring DIagrams"

 

[jim coulter]

Thanks JonM. I've got the electrical schematics. Since the car is fiberglass, I figured that somewhere the wiring bundle probably passes through metal or next to metal, and its been rubbing and finally got to the point of going to ground when jolted. Figured I'd have to start at the tail lights and work my way toward the front, unless there where a couple of prime spots to check first. Thanks, and wish me luck.

 

[JonM]

Their are two major grounds for the lights...one on the left hand side of the radiator support (front lights) and Above the right wheel well (rear lights)

 

[jim coulter]

Thanks, but I dont think the grounds are the problem. More than likely the hot wire (either going to the switch, or leaving the switch going out to the lights) is rubbing against a metal part of the frame somewhere therefore "shorting" the hot wire to ground and blowing the fuse. I was curious where this "hot" wire might pass close to the frame or through the frame. Thanks for your help. Looks like this will be a time consuming task.

 

[geekinavette]

Jim, couple 'o questions:

Which fuse is it exactly that's blowing? Is it the one labeled LCD?

By "running lights" do you mean the fog lights, or park lights, or...?

One area I've had trouble with is where the "breadloaf" attaches under the dash. It uses metal mounts that are grounded, and lots of wires run through that area straight from the fuse box.

Good luck!

Bill

 

[jim coulter]

Its the fuse marked "tail" and its the tail lights, parking lights, and all lights on the dash, center console included. What do you refer to by "breadloaf"? Thanks for the help.

 

[vigman]

Bread loaf

The big BULBUS thing on the passenger side of the dash.

2 thoughts

1) What are you doing when the fuse goes...

a) Just driving.. no stepping on the brake or using any other controls?

b) When the fuse goes.. are ALL the lights on?
( assuming your driving @ night )


I would first check the following

Starting with the rear, the looms run all around metal subframe for the tail lights & the plate lights... not to mention the bulb for the spare tire.

I would replace all the taillight bulbs

as the glue wears out ( glass bulb to socket,brass).. the bulb sags a bit SOMETIMES allowing the internal leads of the bulb ( outside of the glass envlope ) to touch the brass outer case ( ground ) POOF

Instant short..

I had this happen on my 84... and it had me going fo a week...

I would start there FIRST.

Be advised changing C-4 early ROUND tail lights are a PAIN....



Good Luck,

Vig!

 

[jim coulter]

Thanks Vig.I was just driving and it was early morning. Its still dark when I get to work. Hit a little bump in road (which with z-51 feels like big bump) and "poof" all dash lights went out. Got to work and backed into the spot I usually park and thought it looked kinda dark behind me when I backed in, so left car running and lights on an looked. Found that the rear lights were out as well as parking lights on front. Checked fuse and it was blown. Replaced and everything was fine till driving home. Hit bump(different one) and "poof" all lights go out again. I worked on the 71 today, plan on working on 84 tomorrow morning, so I'll start at the rear like you said. I've never worked on the rear lights, I'll get the manual out and read up on it tonight. thanks

 

[geekinavette]

Ahhhh ok. Yep, sounds like the rear is a good place to start.

Good luck with it!

Bill

 

[SPANISHVETTS]

Be advised changing C-4 early ROUND tail lights are a PAIN....

I have had exactly the same problem with the bulbs.

If you are my size, (6´+200#), get your self an elf to change the back lights. I once got my arm stuck between the gas tank and frame. We had to slide a piece of Teflon between my arm and the tank to get my arm out of the hole with most of my skin still attached.

The rear lighting harness on a C-4 is easy to get to. It runs down the right side, up over the wheel well, and out through a grommet in the upper right corner of the rear compartment, just above the right rear speaker.

On mine the wiring from the grommet to the lights looks like a bird’s nest. If it is not one of the lamps, I’ll put my money on a hot wire chaffed and touching the rear frame.

 

[SPANISHVETTS]

Be advised changing C-4 early ROUND tail lights are a PAIN....

I have had exactly the same problem with the bulbs.

If you are my size, (6´+200#), get your self an elf to change the back lights. I once got my arm stuck between the gas tank and frame. We had to slide a piece of Teflon between my arm and the tank to get my arm out of the hole with most of my skin still attached.

The rear lighting harness on a C-4 is easy to get to. It runs down the right side, up over the wheel well, and out through a grommet in the upper right corner of the rear compartment, just above the right rear speaker.

On mine the wiring from the grommet to the lights looks like a bird’s nest. If it is not one of the lamps, I’ll put my money on a hot wire chaffed and touching the rear frame.

 

[jim coulter]

Thanks guys. Wife just left for church, going out to work on 84. Watch me get my arm stuck and have to wait till the wife gets home to escape:eek Oh well, wish me luck. By the way I'm 6' and weight 205. perfect "stuck" weight sounds like. Thanks for the help.

 

[JonM]

Unbolt the bolt holding the muffler in place in the back...makes it easier.

 

[jim coulter]

Just took the back-up lights out. The left one was like you said, the glass was loose from the base. Was just wondering how to get to the others, really tight fit for my arm. Thanks for the tip about the muffler bolt, I'm going back out to try that now.:crazy

 

[jim coulter]

O.K. tried the muffler bolt, that allows you to shift the tail pipes alittle, but my forearm still wont fit through the little gap to reach up and grab the other lights. With the broken bulb out I reached up and grabbed the harness through the license plate opening and with the lights on wiggled and pulled it as much as possible, but nothing blew. Did find a connector that is suppose to be snapped to something that was loose. Not unplugged, but just not attached. The wires come out of the harness and go to this plug. The wires going to this plug, have been rubbing on the gas tank. You can see where they have rubbed a smooth spot on the tank. Think I'll tape these wires from the harness to the plug and fix the broken back-up light bulb and see what happens Monday on the way to work. In the mean time, I'll study the situation and see what I can do to get to the other lamps. Thanks for all your help. Any other suggestions to try and reach the other lamps will be greatly appreciated.

 

[vigman]

At 6' 0" 245

There are nuts that attach the the base of the rear end plastic to the frame and the bottom ( below the license plate... running twds the mufflers remove these and you will get another WHOPPING 1/2 inch of clearance due to additional flex of the rear end rubber.

That's about ALL your gonna get.. you HAVE to make it work.. the other option is less pretty

remove wheels, remove wheel wells plastic , remove antenna ( drivers side ) remove side marker light and get a kid to wriggle up into the fender to get the outside ones.


Now you know why I have 96 rear end plastic

10 min.. all 4 bulbs out... 10 more minutes all new bulbs in & reflectors cleaned.. and a sweat was never broke.

Good luck


Vig!

 

[jim coulter]

Thanks Vig. I found a bulb like you said, but it was on the back-up lights, so I doubt that would have done it unless I was backing up. I found some wires against the tank which I taped. Drove it around and hit every bump I could find(with the lights on) but nothing blew. Tomorrow I'll loosen those bolts up and try to get to the other lights. Thanks for the tip. Hope a 1/2" is enough. Guess I could "fast" for a week and lose enough weight to get there:L

 

[vigman]

Hire the local BEAN POLE kid

There is NOTHING easy about that job!


Vig!

 

[jim coulter]

Guess I'll have to train my 11 year old on tail light removal, and if that doesn't work I'll try my 9 year old Thanks for the help. I'm going to try it tomorrow after work. Maybe that 1/2" will be enough:Silly