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weird short of some kind between parking lights and stop lights

Started by chargerdon, January 24, 2018, 02:11:10 PM

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chargerdon

This is all on my fairly stock 1974 base challenger.   All of my lights worked for months.   Then other day the Blew a fuse for the parking lights/dash lights the other day..   and since then things are truely weird.    It will blow the  fuses immediately for the parking lights/dash lights MOST nearly every time i put in a fuse (20 amp) even if the parking lights are not turned on.   I even tried removing the Headlight/parking light switch to see if that was were the short was, but, it would still blow the fuse.   

I noticed that while the fuse was blown for the tail lights, that this also controls the light for the steering wheel key hole which normally is activiated by opening the door, but that the keyhole light will work with fuse out if i push on the brake !!  Noticing this i began experimenting with the fuse for the stop lights.   If i remove that fuse, then i can put IN the fuse for the tail lights/instrument panel/ key hole and they WORK !...   Or with that fuse out, i can put in the fuse for the stop lights and they will work.   Just not together when both fuses are in. 

So both circuits work independently when its fuse is in, although with some issues, but if both fuses in then the taillight/instrument fuse will blow.    However, sitting in the car, and push on the brakes (without fuse in it for stop lights) the steering wheel key hole light will come on !!   

With fuse IN for stop lights, and tail/instrument/steering wheel keyhole light fuse OUT, I will usually get a very faint light out of the key hole light.   Disconnecting the battery and putting on an ampmeter between ground cable and ground post ill read between .1 to .15 amp when that little light is on...   very strange.  If i then turn on the switch for tailights (fuse still out) then the keyhole light goes out or if i open the door, then that faint light goes out.

I obviously have a short between the two circuits...but...   where to look??      In testing with both fuses out, if i put a multimeter between the two "out" sides of those two fuses i show connectivity...so definite short, tho not solid or those circuits wouldnt work individually. 

On suggestions on where to look ??   Im stumped.. 

Chryco Psycho

I think I would start with the column , unplug the turn signal switch & ign light plugs , if that changes nothing plug it back in &  then remove the kickpanel & unplug the tail lights , see if you can narrow down where the issue is

RUNCHARGER

Hmm: Most likely in the column but all you can do is unplug harnesses until you find it. Even a bulb pigtail could do that.
Sheldon


chargerdon

Quote from: RUNCHARGER on January 24, 2018, 07:21:22 PM
Hmm: Most likely in the column but all you can do is unplug harnesses until you find it. Even a bulb pigtail could do that.
Thanks guys...   

I had an ohmeter in the fuse block between the out sides of the stop light fuse and tail light/instruments fuse and it was showing about 38 ohms...   so not solid short..but definite feed back.    went to the kick panel and pulled apart the connector which has in it the door switch and other wires (7 wire connector) and no connectivity..so no short.    Examined but saw nothing wrong..so plugged it back together and still no short...  reconnected battery, put in the fuses and everything except dome light wasn't working.   

Took connector apart again pulled out each blade and sanded..then cleaned the inside of that half of the connector, and put all the blades back in.   Then ran a thick blade into and out of each female connector on the other side, put it all back together and put back in the fuses and now everything works.   Never really did see anything that was wrong, so im guessing there was enough corrosion inside the connector to cause the partial short.   

Yeah, back to "normal".    Thanks again for being there for me.

RUNCHARGER

Hopefully a loose terminal. I always put contact grease on everything these days. I would leave the kick panel off for a bit and maybe feel the  connector for heat once in awhile.
I find that connector in bad shape quite often, water gets in there when these cars get old I guess.
Sheldon

Chryco Psycho

Glad you got it solved , I use di-electric grease on all connectors also

dodj

Quote from: chargerdon on January 26, 2018, 01:44:25 PM
Quote from: RUNCHARGER on January 24, 2018, 07:21:22 PM
Hmm: Most likely in the column but all you can do is unplug harnesses until you find it. Even a bulb pigtail could do that.
Thanks guys...   

I had an ohmeter in the fuse block between the out sides of the stop light fuse and tail light/instruments fuse and it was showing about 38 ohms...   so not solid short..but definite feed back.    went to the kick panel and pulled apart the connector which has in it the door switch and other wires (7 wire connector) and no connectivity..so no short.    Examined but saw nothing wrong..so plugged it back together and still no short...  reconnected battery, put in the fuses and everything except dome light wasn't working.   

Took connector apart again pulled out each blade and sanded..then cleaned the inside of that half of the connector, and put all the blades back in.   Then ran a thick blade into and out of each female connector on the other side, put it all back together and put back in the fuses and now everything works.   Never really did see anything that was wrong, so im guessing there was enough corrosion inside the connector to cause the partial short.   

Yeah, back to "normal".    Thanks again for being there for me.
Glad it's working for you,  but, i hate that kind of fix. (not really sure how it was fixed). Corrosion in a connector usually prevents a cct from working. Not blow fuses.
Again,  I'm glad it is working and i hope you fixed it via cleaning the connector, but i think you will be revisiting this issue at some point and i would examine the wires leading from the connector you unplugged/plugged if it happens again. 
"There is nothing your government can give you that it hasn't already taken from you in the first place" -Winston Churchill


Katfish

I agree with above, it's more likely that with all the work you did, a wire that possibly had it's insulation worn through was moved away from the whatever it was shorting to.

Look closely at the wiring for nicks or cracks in the insulation, especially near sharp bends.
These wires are super brittle after 40 years.

chargerdon

Yeah...i examined the wires as best i could and saw nothing wrong with them...   Im thinking that there was enough corrosion..that it was causing the "partial" short between the blades...   this time i put di-electric grease on them after cleaning..   So...hopefully it will be ok...

I know this...if problem comes back will look there first...

Also, after "fixing" the problem, i am curious on one thing.   If i take the negative battery cable off, and then use my multimeter in amp reading on it between the cable and the negative post and it reads .01 amp...   I THINK the slight draw is from the radio keeping its station settings and clock alive.   Is this still too much...or nothing to worry about?   I read where the average auto battery has 48 amp hours of energy...   so 48/.01 = 4800 hours so to "half drain" would be 2400 hours or about 3.3 months...   So, i guess this is ok... 

dodj

.01 amps is fine. Your battery will last a long time between starts with that kind of draw.
"There is nothing your government can give you that it hasn't already taken from you in the first place" -Winston Churchill