Strange electrical mystery on my 84! (Page 1/2)
johnt671 JUN 21, 04:35 PM
I'm having a weird problem with the circuit protected by fuse # 11. That's the horn relay, dome light, stereo memory and cigar lighter. My set up has been the same for 15 years, no changes, nothing removed and reinstalled. The stereo is a newer Pontiac am/fm/cd player I bought off someone on the forum and had been working great.

A few weeks ago while driving the car that whole circuit started to cut off then on. The only thing I was using on that circuit was a dash cam, nothing else. Finally the circuit ceased working at all. I've driver the too and from shows for years with the dash cam and a gps plugged into a splitter and the cd player on and never had a glitch. I thought the fuse was bad and replaced it twice. Both times I started it up the circuit cut out. But now for the puzzler, the two fuses were good, and the circuit came back on line then cut out when I started the car with the same fuse in the box.

What the heck?

[This message has been edited by johnt671 (edited 06-21-2020).]

RWDPLZ JUN 21, 05:24 PM
Replace the cigar lighter socket.
theogre JUN 21, 06:43 PM
See my Cave, Lighter

Socket could be bad but....
Possible socket has some crap and shorted out. May not be a "Hard" short that blows a fuse.
Many Dashcam, USB, and other power adapter are made very cheap and often fails and shorts out even when they has a fuse built into them.

Many "power plugs" may look OK on the outside but inside has crack plastic parts etc. and short out where you can't see.

If socket is bad...

quote
Originally posted by RWDPLZ:
Replace the cigar lighter socket.


But note that replacement socket don't have the "Crow bar" shown in the cave. Is likely a big part of why the circuit "blinks" when adapter or socket has problems.

Find a Casco replacement. Many part stores and others sell no-name cheap one that's often worse then Casco likely make in China now too.

------------------
Dr. Ian Malcolm: Yeah, but your scientists were so preoccupied with whether or not they could, they didn't stop to think if they should.
(Jurassic Park)

The Ogre's Fiero Cave

johnt671 JUN 22, 08:33 AM
I'm going out soon to check the lighter socket out. Keep in mind that the fuse (#11) isn't blowing out, and if I put the same fuse back in it seems to reset the circuit. The whole circuit cuts out when I start the car even with nothing plugged in the lighter socket. The only thing on at that point is the memory on the stereo. Thanks for giving me some direction on this.
johnt671 JUN 22, 12:21 PM
When I went out, the dome lights came on when I got in the car. When I parked it two days ago the whole circuit was dead. I started the car and everything still worked. So I shut it off and pulled the cigar lighter out. It's an old one and crusty inside. With the lighter out but connected I again started it up and all was good. With the car running I started to tighten the lighter down and I lost the circuit. So I rechecked the wires and found one needed to be bent a bit. Put everything back and it seems good now.

I'm not ready to say it's fixed until I drive it some. but I will be looking for a new socket.
johnt671 JUN 22, 01:36 PM
Just went out to drive it and the circuit is dead again, fuse still good.
Chris Eddy JUN 23, 03:23 PM
Thinking out loud..
If the lighter socket is bad, the only mode is shorted out. If shorted out, it would blow the fuse. An open lighter socket only affects the lighter socket.
Other than blow the fuse, one branch of the circuit cannot make the other branches not work.
And on grounds, again, if there are many return paths, one open ground cannot make all branches stop working. Unless there is only one ground return.
The issue seems to come and go easily, IE it is not intermittent over weeks or such long times.
Can you get a meter and see if you can "catch" 12V power before and after the fuse? Chop this problem into parts?
theogre JUN 23, 05:33 PM
Leave socket unplugged for a few days and see if problem goes away.


quote
Originally posted by Chris Eddy:
Thinking out loud..
If the lighter socket is bad, the only mode is shorted out. If shorted out, it would blow the fuse. An open lighter socket only affects the lighter socket.
Other than blow the fuse, one branch of the circuit cannot make the other branches not work.
And on grounds, again, if there are many return paths, one open ground cannot make all branches stop working. Unless there is only one ground return.
The issue seems to come and go easily, IE it is not intermittent over weeks or such long times.
Can you get a meter and see if you can "catch" 12V power before and after the fuse? Chop this problem into parts?

Lighter & the Socket often "goes bad" and Won't blow a Fuse.

Sockets "go bad" for several reasons... highlights:
Ashes etc get trapped and draws enough water out of the air causing problems.
Arms that hold the lighter pushed in cracks or breaks. The arms are bi-metal and "wear out."
Ceramic part cracks/breaks causing problems.
Can be any combination of all.

Typical results:
hard short and blow fuse.
soft/restive short will pull power but not enough to blow fuses.
just won't work.
Plus Soft shorts and lighter stuck in can heat up and "trip" the "Crow bar" w/o blowing the fuse. This "Crow bar" feature, I've only seen it in Fiero. Most other cars have a lot of room so when a lighter malfunctions the car won't fry.

For problems w/ arms holding lighter... Many try to bend "weak" arms to hold again... Do Not do this. Often the arms will fail and can keep holding light on then try to fry things including the Fiero console.

Most things in the cabin share only 2 main grounds... G201 (Behind Radio) and G202 (Below ECM) but many things has one to several splices to get to those.
I would clean both and others and metal go onto and coat w/ brake or silicon grease just as PM even if that look ok to you.
See my Cave, Wire Service

Dome light alone won't care w/ bat fuse circuit but GT and some others have foot lights... If you have that option, See my Cave, Sneak Path

[This message has been edited by theogre (edited 06-23-2020).]

johnt671 JUN 23, 06:13 PM
I replaced the lighter socket but it didn't help. Boy, the one that was in there sure was crusty. I did get another clue, No headlights or tail lights. At this point I realized I'd had this problem before. While everything working I went back to the battery and wiggled the + cable and everything went off. Another wiggle and all came back on.

I saw the cable was a little loose so with high hopes I tightened the cable down and took it for a ride. Everything was looking good for 15 minutes and then died. A few minutes later it came back on and stayed on until I got home. another wiggle and it shut down.. I have it down to one of the two secondary wires off the + side of the battery.

I should point out that the wires were a mess when I bought the car and a few years ago I did a rewiring job to make the wire a lot neater and cleanner. So tomorrow I plan on taking the wire ties and looms off and see what I can find. Thanks again for the advice.
johnt671 JUN 23, 06:16 PM

quote
Originally posted by Chris Eddy:

Thinking out loud..
If the lighter socket is bad, the only mode is shorted out. If shorted out, it would blow the fuse. An open lighter socket only affects the lighter socket.
Other than blow the fuse, one branch of the circuit cannot make the other branches not work.
And on grounds, again, if there are many return paths, one open ground cannot make all branches stop working. Unless there is only one ground return.
The issue seems to come and go easily, IE it is not intermittent over weeks or such long times.
Can you get a meter and see if you can "catch" 12V power before and after the fuse? Chop this problem into parts?



I do have a meter so if what I want to do tomorrow fails I give this a go.