Wiring issues again

[68c10guy]

So i've had this problem twice now, first time it was a bad fuse but now a new fuse hasnt fixed the problem, when i turn on the headlights i have headlights and turnsignals and all that jazz, but i have no dash, dome, or running lights. Anyone had this problem? could it be a bad ground?

[VetteVet]

Only one thing will blow a fuse and that is too much current going through it. This may be caused by too small a fuse for the load in the circuit or a ground in the circuit.
I would guess it's the latter and most often in your case it is the dome light wires that run under the sill plate over the rocker panel. Sometimes the wires are just run under the floor and up to the light, so it may take some looking to find them. They should be orange and black with the orange wire being hot. Did the new fuse blow also?

[WorkinLonghorn]

If you're saying the fuse is still good and you don't have running,dome or dash lights, then you need to check the connections at the headlight switch and possably replace the switch. If you are still blowing fuses then do like Vettevet says and also check each circuit for shorts.

[jef5150]

Originally Posted by 68c10guy

but i have no dash, dome, or running lights. Anyone had this problem? could it be a bad ground?

the dash,running lights,and dome are on the same fuse,
The dash/parking light are grounded by a black wire clipped to the bottom of the dash.

but the dome light is grounded by your light switch, making contact with the metal portion of the dash make sure there is no paint/rust on that surface.



jeff

[68c10guy]

The new fuse did not blow out, and i also checked and i dont have brake lights either, which presents a safety problem. So am i looking for a bad ground? or a bad wire or what/ Thanks in advance

[jef5150]

CHECK FUSE 1ST


pull the wire connector off your brake light switch(orange/white wire)
(there are 2 clips,1 on each side)
take a piece of wire and jump the connection, CHECK if your brake lights come

jeff

[68c10guy]

Is that the switch mounted on top of the brake pedal assembly?

[michael bustamante]

Originally Posted by jef5150

the dash,running lights,and dome are on the same fuse,
The dash/parking light are grounded by a black wire clipped to the bottom of the dash.

but the dome light is grounded by your light switch, making contact with the metal portion of the dash make sure there is no paint/rust on that surface.



jeff

is that what that ground is??? that thing has been sittin under my dash for years and I couldnt figure out what it was for.
if that ground is not your problem I would try another light switch from a doner veh. could be bad circutry in the light switch itself.
the brake light switch is under the dash to the left of the upper half of the brake pedal it has an orange and I belive white wire coming from it,

[68c10guy]

Ohh ok well hopefully its somthing as simple as a headlight switch, is that something i can get from autozone?

[jef5150]

heres the connector for the brake switch

jeff

[ChevLoRay]

...or NAPA, etc.

[68c10guy]

ok, so im checking the brake light switch, or the headlight switch? thanks again guys

[jef5150]

for future reference
in case someone is having a similar problem and cant find the black ground/clip
(p/o cut it off)
it comes out of the wiring harness here
with the gray wire for the light bulb that goes in the heater controls.



jeff

[68c10guy]

ok so just changed both the headlight switch and brake light switch and still nothing! i need it fixed soon because its my daily driver. Thanks again

[michael bustamante]

you said the new fuse is not blown now right? Do you have power going to the fuse housing for that fuse? time to get out the ol light tester

[68c10guy]

new fuse is fine, havent checked for power yet. Keep the ideas coming!! thanks

[jef5150]

YOU need to establish that you are getting power and you have a good ground before you start replacing anymore parts.

did you find that ground wire????
///////////////////////////////////////////
go get a piece of wire
put your lights on ,
turn your dome light on,
hold 1 end of the wire on bare metal,
touch the other end of the wire to one of the places in the picture with red arrows

...tell me what happens
(you dont have to take the switch out of the dash, mine happens to be out)

jeff

[Longhorn Man]

that ground wire is only for the inst panel. NOT for anything else, and it will NOT prevent any of these other things from working.


EVERY itme you've listed that is inop, is all run off that one single fuse.
The fuse can pop and still look good. CHECK FOR POWER on both sides of the fuse.
I'll bet a punch in the gut the fuse is blown.
Now, if I am right, you'll need to figure out why your fuse is blowing.
The #1 reason for that fuse to blow, is tail light harness being damaged and grounding out.
If the fuse blows as soon as you install it, then I would suspect the harness for the dome light as mentioned. It is hot all the time, all the way up to the light assembly.
If the fuse stays good untill you hit the brakes or a turn signal, then you know you need to look at the yellow and the dark green wire in the tail light harness.
If it pops when you hit the parking lights, then the brown wire in that harness.
I would look under the bed in the bumper area first, where the harness has been hacked over and over for trailer harnesses.

[mr48chev]

As Longhornhorn man said, you will have to do some checking and eliminating.
If you don't already have a good test light get one. Most parts houses, tool trucks and Sears stock good ones for under 15.00 that you should be able to use for years. You want the 12 V dc test light not the continuity tester. NAPA usually has one with a cord on it that is several feet long so you can hook the clap to a good ground and test away without moving the ground clamp all the time.
As it is the circuits that the tail and stop lights are on you want to confirm that you do have power to the switches.
The orange wire is the hot wire to the brake light switch. It should be hot all the time key on or off. With the test light test there to make sure you have power there. If not, backtrack to the fuse block.
If you have power into the brake light switch you need to check it to see if it works.
The white wire leads to the turn signal switch from the brake light switch.
coming out of the connector to the turn signals switch under the column or close to it you will see the following.
The yellow wire is the left turn/brake wire
the dark green is the right turn/brake wire.
light blue is left front turn
dark blue is right front turn
Black should be the horn.

At the back of the truck
Brown is tail and side marker
Yellow is left turn/brake
dark green is right turn/brake
light green is back up lights

There is a connector that goes through the rear most crossmember on the drivers side that the contacts sometimes get cruddy in or it sometimes gets disconnected if the wires get pulled on or if the bed has been pulled off. It is a good place to test to see that each circuit has power that far.

On these trucks I have found that if the problems aren't under the dash or in the switches they can usually be found in=
1. Extra wires that were used for trailer hookups.
2. The trailer connector it's self. They tend to get cruddy after a while.
3. Bad grounds. Each socket and light is grounded by a wire to the bed and sometimes these wires get broken, cut or loose.
4 bad sockets that have corroded causing shorts.plus the remains of wires that were connected to them.
5 those little (usually blue) squeeze on wire connectors that are quite often used to connect trailer wires
Those are the things that I have found that usually cause problems at the back of these trucks. My 71 is my third one of these trucks that I owned plus all of them I worked on over the years for other people.

[lks dcvn]

with Longhorn Man and mr48chevy - all of this makes sense...

I had a similar problem and removed the rear harness completely from my project truck (saw the blown fuse) and then went through it - turns out one of the POs along the way (38 years) decided that it was cheaper to hack the crap out of the rear harness than to buy a $7-$10 (plug in adapter)...

Fixed the hacks - now it works as it should...

[68c10guy]

Just wanted to let everyone know it ended up being a bare wire in the turnsignal switch

[Longhorn Man]

interesting... was it the white wire by chance?
This is a very uncommon cause.

[68c10guy]

It was the white wire, it got pinched underneath the turnsignal switch and then was rubbed down to bare wire, which caused it to short out whenever i pushed on the brakes.