News:

Due to a technical issue, some recently uploaded pictures have been lost. We are investigating why this happened but the issue has been resolved so that future uploads should be safe.  You can also Modify your post (MORE...) and re-upload the pictures in your post.

Main Menu

Electrical Problem

Started by Fred Wittenberg (clc#18218), January 28, 2006, 03:17:34 AM

Previous topic - Next topic

0 Members and 1 Guest are viewing this topic.

Fred Wittenberg (clc#18218)

Thanks to whomever reads this.
The problem I have is that I was moving my powerseat farther back. After that my headlights, brakelights, horn, powerseats all became non-operational. I have power to some parts of my fusebox, but not at the places that control these items. I checked this with a test light.
I have 1971 Sedan DeVille.
I have heard of 2 possibilities. The first one is that I burned a fusible link off the starter, and the second one is that there is some sort of a main harness that runs under the drivers seat that may have something to do with this.
Any help would be greatly appreciated.
Sincerely,
Fred Wittenberg
Brewster,NY
clc#18218

Porter 21919

Fred,

There is a wiring harness that runs under the seat but I doubt moving the seat backwards caused your problem.

Ive never had a problem with a fuseable link but rule out any wiring harness damage from moving the seat back IMHO.

Maybe an electrical expert here can give you some advice, like Mike Jones, a factory trained Cadillac mechanic and a crackerjack electrical system specialist.

Maybe a shameless plug but so be it, he is an expert.

Porter

Mike #19861


 Thanks for the shameless plug, Porter! ;-)

 I would look at the fusible link on the starter. There are typically at least one there that will feed several circuits. The one that likely has blown will feed the headlight circuit, windows, seats etc. These circuits are not fused at the fuse block.

 The harness under the carpet will only feed the power circuit on the seat. I dont see this as being the reason, but maye the cause for a blown link.

 Once you have returned power to the circuits, investigate the reason for the blown circuits. Is there a short to ground in the circuitry in the seat? If there is, you will likely blow this link again (if indeed that is the cause)

 Mike

Porter 21919

Well Mike,

I seriously doubt backing up the front seat could affect the wiring harness that runs under the seat, which only supplies electric to the rear components of the car.

Perhaps moving the seat backwards aggravated or stressed out a weak link in the electrical system that failed.

I assume if anyone had an answer or a reasonable guess as to where the electrical failure occured you might have one.

In a perfect world we would troubleshoot properly and determine where the problem lies, that is the only proper approach, test work, not guess work.

Porter

denise 20352


   A wiring diagram would be helpful.  Normally I would go from the device to the source, but in this case, where several devices have quit, it certainly does sound like a fusible link, maybe one that comes from the starter.

   You can use a test light or meter lead to find a blown link.  Fasten the ground or negative lead to a solid ground on the chassis.  Touch the positive lead to the terminal that comes from the battery and make sure that it shows voltage, so you know that your test ground is OK.  Then you can poke the wire on each side of each fusible link.   Dont poke into the link itself, and dont poke holes in your fingers like I do.  Obviously if one side of the link has volts and the other one doesnt, the link is blown.

   I understand that there are is also a tool that will find voltage in a wire by induction, so that you dont even have to poke it, but Ive never used one.

-d

Fred Wittenberg

hey Porter,
thanks for the info. maybe Im just being speculative and grabbing at straws!! Ill read Mike Jones reply as well.
My father was a design engineer for GM under Roger Smith. Youd think I would have learned more!!
Fred

Fred Wittenberg #18218

Mike,
I guess that would explain alot. I did take a test light and check the fuse box. Parts of the fusebox do have power, and parts do not.
It still is intersting to me though that I still have signals, and reverse lights, but no horn, headlights, or brakelights. Fusible link!! Lookout here I come!! Is there a way to move that circuit onto a circuit breaker instead of burning the fusible link next time around? I know I need to locate the reason it failed, but maybe as a precautionary method for the future?
Well, maybe better just to leave it alone.
Just a sidenote: I used to have a 1967 DeVille convertible, which was lost tragically to a garage fire, which I used to have reprint of the GM shop manual. Where can I obtain a reprint of a shop manual for this 1971?
Fred

Fred Wittenberg

Denise,
Definitely checked my fusebox with a testlight. 20 minutes later, and some bloodletting, I have discovered that parts of the fusebox have power, and some do not. Found a wiring diagram via the Internet. Gonna see where it goes from here?
Fred

Fred Garfield 22310

Heres a link to an original used 71 shop manual at ebay motors --

http://cgi.ebay.com/ebaymotors/1971-Cadillac-original-shop-manual_W0QQitemZ8034249573QQcategoryZ34212QQrdZ1QQcmdZViewItem TARGET=_blank>http://cgi.ebay.com/ebaymotors/1971-Cadillac-original-shop-manual_W0QQitemZ8034249573QQcategoryZ34212QQrd

$20 and shipping buys it now

There are also many other manuals listed at ebay motors, some of them reprints

Good luck!


Rhino 21150

Headlights, horns and brake lights are always on devices, meaning they work without the key in the switch. So are most electric seats. If they all quit when you moved the seat back then something metal dragged by the seat cut through the wire supplying power to the seat, and shorted it to the body. Could also be the switch is damaged and shorted internally. This blew the fusible link and the headlights, horn and brake lights were also getting their power through the link. Look under the seat for a cut and shorted wire. Loose stuff is a health hazard to wiring! You may also have a blown fuse for the seats, but the others wont be blown.
The other electrical items get their power through the ignition switch which does NOT go through the link. So part of the fuse box will have juice and part will not.
You must check under the seat, that is probably where the initial problem is.
The fusible link can be replaced with a self resetting circuit breaker. Ask the local parts guys (Auto Zone, Advance, whatever) to find the right current value. DO NOT over size the breaker, harnesses start nasty fires when you do that. The breaker will have electrical connections that dont match how the link attaches, get a competent electrical person (you?) to attach appropriate leads. If you leave the breaker dangling under the hood be sure to insulate it so it doesnt short either.  

Fred Wittenberg (clc#18218)

Thank you so much for the link!! I just bought it!!

Fred Wittenberg (clc#18218)

Bid on this one too!!
You are truly the info man!!
I am greatful!!

Fred Wittenberg (clc#18218)

Thanks Rhino!!
I will check under the seat first to insure that I wont re-short the fusible link when I have my mechanic repair it. I have found a repair shop locally that caters to the cars of yesteryear.
Fred

Fred Garfield 22310

Always glad to help. We Freds have got to stick together. ;-)