hotrod electrical system problem, help before I shoot it!

[jmg944t]

I have my dad's 29 Model a roadster he just bought. The brake lights didn't work.

upon inspection I found THE WORST wiring I have ever seen. here is an example- 14g Black to 20 g red to 20g black to 16g black ALL IN 2 FEET!! I swear to god whoever did this had a box of little pieces of wire he had to get rid of because the whole thing is like that!

As there was no logical wiring I traced each wire back to where they come into the trunk and identified each and cut. I gutted what was left.

THE PROBLEM-
I can't make the brake lights work.

Here is what I have done.

Jumped fixure +/- to battery-fixture works
used test light from hot wire to battery ground stepped on brakes- works
tested battery voltage- works
Tested ground with light- works

and a bunch of other tests but for some reason every time I hook up hot to fixture and ground to good ground it doesn't work....

I just thought maybe a broken ( new) wire that I am trying to install.

Any suggestions?

[mr.clean]

http://www.painlesswiring.com/

[gfinch]

Probably the ground. You did try a different bulb that is the correct one for the socket, right? is the socket CLEAN . Anything rivited is suspect!
Do a "Voltage Drop Test" on both the Power and Ground sides of the system.
Check for a voltage reading between Battery positive and the socket at the light. Attach one side of the volt meter to the battery and the other side to the socket. Power up the system should be less than .2 volt. What your doing is seeing if there is excessive resistance in the circiut when power is applied= voltage drop. If the load/light needs more power then the original circiut/wiring can supply the power will go thru the volt meter.
Lets say you get a voltage reading of 6 volts showing on the meter. What you are going to do is take the meter wire at the socket and start checking the connections on the way back to the battery.
When you see 6volts on one side of, lets say, the brake light switch and .2 volts on the other side you have found a 5.8 volt drop in the switch itself, bad switch.
You test the ground side of the circiut by connecting one side of the meter to the negitave post of the battery and the other to the lights socket. Its the same drill checking connections leading back to the battery. The bracet holding the light, the bumper, the bumper bracket attaching it to the frame....

IMHO.This is the best way to test an electrical circiut, under load.

[Superdave]

http://hotrodders.com/
SD

[jmg944t]

Well, I almost took it out of the garge and shot it in the gastank.

I had two problems one was my own lack of knowledge, the other was a Gfinch described. Bad switch but only under load not on a test light. My lack of knowledge was that the brake signal goes to the column which cuts it up for directionals and hazards. I got that from Painless. Thanks Mr. Clean!

I didn't know that and didn't figure it out easily as it was wired so poorly to start off with as there were "brake" signals wired in wrong to begin with.

So you responded with the info that kept me from shooting a car and having my dad shoot me, you saved a life today guys, I appreciate it.

[gfinch]

Glad to help. Hope you tested to fix. If you use this method a few times you will be able to fix almost any electrical problem. You will start to see the circiut in your minds eye.

[BUSHWACKER]

where's the pics of the car, now that it has brake lights that work:p

[triple dude]

Bad grounds lead to all kinda goofy stuff. When I used to apply the brakes on my GTO, the dashlights would dim. And blow fuses. I replaced the trunk wiring harness with new bulb sockets/ground and all was okay.

[BUSHWACKER]

Years ago a friend brought her Maverick to me, when she stepped on the brakes, or put the t/s on ALL the marker & parkin lights wood come on...r/f bulb was old both lead contacts had been smashed down so much they were touchin each other, looked like the STARSHIP ENTERPRISE w t/s on :D

[jmg944t]

I should be able to post pics tomorrow when it isn't raining and I can take it outside.

[OrangeCrush]

Hows the rest of the wiring? if it's as bad as the ones you replaced dont mess around buy a kit, replace everything. it's easy and there are a lot of opinions. not worth catching fire running down the highway.

[gfinch]

Here's one. Turn the left turn signal on and the turn lights would flash three times then stay lit without flashing, until you turn them off. Each time same thing.

Another: My Lance camper. During the winter the heater blower fan would burn fuses, but only if cold enough. I put a circuit breaker in the fuse panel.Problem went on for several years. On day at home I was checking out another problem, had the stove/oven pulled out. When I noticed the fan circiut breaker clicking on and off. This was the first time I could get it to do it other than on a trip.
What it was: the wire to the fan laid on a screw, which wore thru the insulation. That screw would touch the gas supply pipe causing the short to ground. Pipe was grounded, screw wasn't.This would happen only when cold enough that the pipe would warp and touch the screw. I didn't want to cut into the wall to fix so I cut the screw shorter so it wouldn't touch anymore.

[BUSHWACKER]

1976 2002 BMW had a real problem car left turn wood blow fuse sumtimes, some nitwit at a body shop screwd a 1/16' plate on to fix rust b4 he filled it on lower l/f fender, did he really have to use a 3 1/2" long one? :p the point just made it thru insulation, I had to get to it with die grinder pointed tip thru access hole after removin kick panel didn't want to have to refill & paint :eek: