Struck down by the electrical gremlins - Vintage Mustang Forums
 7Likes
Reply
 
Thread Tools
post #1 of 25 (permalink) Old 04-26-2018, 10:25 PM Thread Starter
Senior Member
 
kiwinz's Avatar
 
Join Date: Feb 2016
Location: Portland OR
Posts: 118
Struck down by the electrical gremlins

Ive heard about them, and thought they'd never get me. Now my car is in pieces in the garage, and I'm defeated. I'm not sure anyone can help, other than offer sympathy. This car has new wiring from a PO, and I am not even sure what fuse panel is in it. Ive traced the wires everywhere and they all look fine.

It seems like it should just be a grounded wire somewhere, but I'm getting more confused and deeper into a complete mess of undone parts. My gauge bezel is back out, headlights and taillights are out, kick panels are off, and tools and small parts are everywhere, and I just walked away from it all. Basically my fuse for the park and tail lights blows instantly. The fuse is showing a ground coming in on one side, actually a few unused fuse spots are showing the same ground. Its messing with my head. So a wire somewhere is grounding. But I mean its a biggy, the fuse blows instantly and with sparks (because at first I was thinking - oh, I'll just replace the fuse - which is a 10 amp and went through my stash of 3 spare fuses), so I got out my volt meter, and ended up using a PowerProbe, and just tried chasing the wires with a short finder (ECU 3000 from PowerProbe). Yeah, I bought the kit to fix this mess and I'm still defeated. Cool tool though, and I'd wanted it for a while.

I went for a drive last week, as I so badly wanted to drive after the long winter and promise of nice weather. I went one day too early. Got caught in some heavy rain, and hit some good bumps on the road (all could be reasons). First time Ive driven it with lights on so long in the rain, the wipers going all the time, and the longest trip Ive done in it to date. I'd just replaced my gauges and forgot to connect the speedometer correctly (realized when I left so just used Waze). I pulled the gauge bezel out to fix the issue, and then realized my gauges lights weren't dimming, then noticed my lights weren't working and spotted the fuse. I may have used the light switch pretty harsh in testing this first issue - over and over. But I removed that from the equation since.

So if you made it this far. I'm just frustrated, and utterly confused that I am finding grounded circuits everywhere. No fuse panel should have a ground in it, and the taillights should'nt be showing a ground... should they? Even with a ground coming from the tail lights two wires - when I throw a positive to it with the powerprobe, they light up correctly. Do that at the fuse panel and it blows the probes internal fuse. So I feel like a complete idiot at this time, and am questioning my sanity on understanding wiring for positive and ground! I'm not a beginner at this, just with mustangs....

The beer tastes good right now though
kiwinz is offline  
Sponsored Links
Advertisement
 
post #2 of 25 (permalink) Old 04-26-2018, 10:49 PM
Senior Member
 
Tallguy's Avatar
 
Join Date: Apr 2016
Location: NorCal
Posts: 808
I am in the middle of re-wiring my 66 with the AAW kit, so neck deep in these details. Much of what I say you probably already know so maybe more of a sanity check. The parking lights and tail lights are one in the same. Brake lights and turn signals are separate. The fact that you are blowing the fuse as you state tells you you have a dead ground short between the fuse box and the tail lights. This also makes sense that you can light the lights up by supplying voltage locally. The wires probably run through the dash, down the driver side and into the channel under the door then into the trunk. May have been pinched or cut or whatever. Not a simple way to track it down other then tracing the wiring down
Daisy and kiwinz like this.

66 Convertible. Full restoration in the works
Tallguy is offline  
post #3 of 25 (permalink) Old 04-26-2018, 10:53 PM
Senior Member
 
Join Date: Mar 2018
Location: Denver(ish)
Posts: 730
Alright, Here's how I see your situation. You have been troubleshooting from all angles at once. Therefore, you're chasing your tail. I'm a service tech by trade, but not on cars. But here is how I'd go about it in this case.
1) Choose one end or the other to start at. (Bulb or battery)
2) Chase your voltage (or ground) toward the other end.
3) You'll find it!

Now if I were to guess where your problem is from my couch, it's behind your fuse box. Pull it out and see if anything sticks out. But I have a few questions first.

1) Do you have 12v on one side of the fuse slot with the fuse out?
If so, I'd guess that everything from the battery to the fuse box is okay.
2) Is the other side of the fuse slot grounded?
If so, then it's time to start chasing that wire. I assume it goes fuse-->brake light switch-->bulb. The tail light wire should come from the headlight switch.
3) Are the tail and brake lights on the same fuse? If so, and both headlight and brake light switches are good, then the issue is between the fuse box and those switches.

I guess what I'm getting at is this. You need to break the circuit down into smaller sections. Check those sections, and find out if they are healthy. I like to use any place something unplugs to isolate sections. For instance, if you unplug the wires at the brake light switch, is the load side of the fuse slot still grounded? If so, your issue is now between the fuse and the brake light switch plug. If not, it's after that. Then just keep working your way back.

For now, have a beer. Tomorrow, have a plan! If you want to talk it through, PM me your # and I'll be happy to give you my opinion on things.
Huskinhano, gwstang, Daisy and 1 others like this.
jgrote is offline  
 
post #4 of 25 (permalink) Old 04-26-2018, 11:14 PM Thread Starter
Senior Member
 
kiwinz's Avatar
 
Join Date: Feb 2016
Location: Portland OR
Posts: 118
Quote:
Originally Posted by jgrote View Post
Alright, Here's how I see your situation. You have been troubleshooting from all angles at once. Therefore, you're chasing your tail. I'm a service tech by trade, but not on cars. But here is how I'd go about it in this case.
1) Choose one end or the other to start at. (Bulb or battery)
2) Chase your voltage (or ground) toward the other end.
3) You'll find it!

Thanks, very good advise. I think I started segmenting the problem at first, and then just went crazy

Now if I were to guess where your problem is from my couch, it's behind your fuse box. Pull it out and see if anything sticks out. But I have a few questions first.

Yep, I worked up to that and kept considering it. Finally pulled the fuse box and looked behind and for connecting wires. Nothing obvious.

1) Do you have 12v on one side of the fuse slot with the fuse out?
If so, I'd guess that everything from the battery to the fuse box is okay.
yep, one side 12v and the other is ground.
2) Is the other side of the fuse slot grounded?

For now, have a beer. Tomorrow, have a plan! If you want to talk it through, PM me your # and I'll be happy to give you my opinion on things.
Thankyou for the help and additional offer.

The main thing is this is rewired and the bundles are immense up behind the dash, and wrapped. I was hoping to find an obvious short with some wiggling (the short finder will screech if I find it even momentarily). Checked the obvious ends by the lights and traced it for a while. Haven't unwired the wire bundles as Id assumed Id find a wire resting against metal or a screw. I was suspect of the washer mechanism having scarred a wire. Didn't find it. More searching tomorrow, but I will look at the brake light switch to disconnect that and try isolating from there.
kiwinz is offline  
post #5 of 25 (permalink) Old 04-26-2018, 11:14 PM
Senior Member
 
geicoman58's Avatar
 
Join Date: Apr 2012
Location: Annapolis,MD
Posts: 1,975
I would rather go downtown and get beat up than deal with electrical problems,,,,other than that, I could make a beer run for you!
geicoman58 is offline  
post #6 of 25 (permalink) Old 04-26-2018, 11:18 PM Thread Starter
Senior Member
 
kiwinz's Avatar
 
Join Date: Feb 2016
Location: Portland OR
Posts: 118
Quote:
Originally Posted by geicoman58 View Post
I would rather go downtown and get beat up than deal with electrical problems,,,,other than that, I could make a beer run for you!
Awesome response! Just a short drive for you to bring the beer. I feel I should have a group of onlookers drinking beer and cheering me on

I rebuilt a VW engine 16 years ago. My roommates offered to help if I got beer. Then they stood there each day drinking beer and offering advise, while a friend and I rebuilt the engine. They are still good friends of mine to this day.
kiwinz is offline  
post #7 of 25 (permalink) Old 04-27-2018, 08:46 AM
Senior Member
 
bsolo66's Avatar
 
Join Date: Nov 2014
Location: Lake Mary, FL
Posts: 253
Garage
Do you have the wiring diagram manual for the year of your car? Without it you really cannot trace or test wires and be sure of what you are seeing. They are inexpensive and easily available. I completely rewired my 66FB and found the manual invaluable during the installation.
bsolo66 is offline  
post #8 of 25 (permalink) Old 04-27-2018, 01:59 PM Thread Starter
Senior Member
 
kiwinz's Avatar
 
Join Date: Feb 2016
Location: Portland OR
Posts: 118
Quote:
Originally Posted by bsolo66 View Post
Do you have the wiring diagram manual for the year of your car? Without it you really cannot trace or test wires and be sure of what you are seeing. They are inexpensive and easily available. I completely rewired my 66FB and found the manual invaluable during the installation.
Of course I don't, but I'll get one and take a look. I know its the first place I should start. The wiring seems simple enough to trace, and the wiring is all labeled (just not finding the ground). I don't know if its a painless wiring harness or what is in the car, as there is much more wiring than what is needed for this car. I'll try some more and if I have no luck I'll take some photos and share for advise.
kiwinz is offline  
post #9 of 25 (permalink) Old 04-27-2018, 11:33 PM
Just some guy
Supporting Member
 
GypsyR's Avatar
 
Join Date: Jun 2001
Location: SC foothills, USA
Posts: 18,989
Garage
My first thought is that when you're powering up, you're also powering up the headlights or something and your PowerProbe can't carry that kind of load. Mine has a circuit breaker that clicks off and resets if I do that.
The PO of my '69 decided the car didn't need a dashboard not any wiring. At all. Here's me pasting together one harness out of three swap meet ones.
oscarnielsen likes this.
GypsyR is offline  
post #10 of 25 (permalink) Old 04-28-2018, 01:42 AM
Senior Member
 
Pmustang's Avatar
 
Join Date: Aug 2011
Location: Colchester, Essex, United Kingdom
Posts: 3,102
I no wiring expert but find myself constantly doing wiring

I guess in this case I would check under the step cover plate and also check where the wires pass through the lower a bit pillar and where they travel over the outer wheelhouse to make sure they are not being pinched

Someone could wiggle/lightly tug the wires from the trunk side and you can feel f they are moving in the step area

There are also some tight bends behind the kick panel where they could get pinched/cut

Best of luck and I feel your pain.
Pmustang is offline  
post #11 of 25 (permalink) Old 04-28-2018, 01:51 AM
Senior Member
 
Pmustang's Avatar
 
Join Date: Aug 2011
Location: Colchester, Essex, United Kingdom
Posts: 3,102
Re-written again for clarity

I no wiring expert but find myself constantly doing wiring

I guess in this case I would check under the step cover plate and also check where the wires pass through the lower part of the door latch pillar and where they travel over the outer wheelhouse to make sure they are not being pinched between that and the rear quarters skin

Someone could wiggle/lightly tug the wires from the trunk side and you can feel if they are moving in the step area to see if they are travelling without interference

There are also some tight bends behind the kick panel/door hinge area where they could get pinched/cut

Best of luck and I feel your pain.

1965-1968 Mustangs imported, prepared and sold in the U.K. and throughout a Europe
Pmustang is offline  
post #12 of 25 (permalink) Old 04-28-2018, 04:08 AM
Senior Member
 
Join Date: Sep 2009
Location: Gifhorn Germany
Posts: 361
Garage
If I have a dead short on a circuit which constantly blows the fuse I take a 21 Watt turn signal bulb with a bulb socket & 2 wires then I remove the fuse & connect the wires to where the fuse was taken out. If the bulb lights with full brightness you have a short. Trace the wiring harness tugging & wiggling along it's entire length. When the bulb flickers or goes out you have found your short.

Do it right. ONCE!!
Pony Gaz is online now  
post #13 of 25 (permalink) Old 04-28-2018, 06:39 AM
Senior Member
Supporting Member
 
gordonr's Avatar
 
Join Date: Oct 2015
Location: Virginia Beach
Posts: 432
Isolation is name of the game here. You need to divide the car up into 3 portions. Front harness, Dash and Rear harness of the car. You can do this by disconnecting harness connectors of the offending circuit without disconnecting your power supply to the fuse box. If that's not possible then gain access to an inductive amp clamp. The ones from sears work well and have a peak and hold feature if you don't have one. Being that the grounds are at the components you can clamp the entire rear harness with the meter. Insert your circuit breaker and observe the reading on your meter. If the short is present you will see a reading of 40-50 amps. If it doesn't move on to the next area. At the firewall gain access to the wiring to clamp. The trick here is not to wrap the battery power feeding the dash so move that one out of the way. Not knowing what what harness is in your car, am I correct assuming its GM based? If it is there is a dash illumination fuse pull it and verify its not rated higher than the park light fuse. Anyway visuals, knowing the wire color to chase and if it changes through the harness is key. Good luck!

1969 Mach 1 S code...2nd owner
gordonr is offline  
post #14 of 25 (permalink) Old 04-28-2018, 07:49 AM
Senior Member
 
cash's Avatar
 
Join Date: Aug 2013
Location: Memphis, TN
Posts: 111
Just a note, remember that light bulbs are only a few ohms of resistance when off. If you are using an ohmmeter to check the resistance between the load side of the fuse and ground it will appear to be a short circuit. I don't know the tool you using but it sounds like it was built for this sort of thing so that might not be your issue, but just in case I wanted to throw that out there.

I had a similar issue on my way but my problem was my gauge lights and radio and the lights at the shift lever. It turns out the wire feeding the light bulb at the shift lever was broken and occasionally when I would shift it would short out. I had this problem for years where that fuse would randomly blow just every 6 or 8 months or so. One day I just happen to be in my car in the garage (in the dark) looking at something completely different and when I shifted the car I saw sparks come out from under the bezel that covers the shifter. Took it all apart and there it was.

Good luck man.

______________________________________________
68 Mustang Coupe 289

cash is offline  
post #15 of 25 (permalink) Old 04-28-2018, 09:44 AM
Dez
Junior Member
 
Dez's Avatar
 
Join Date: Apr 2018
Location: Framingbury, MA
Posts: 20
I'm just finishing wiring up my '67 with the AAW kit and chasing a gremlin or two. You might want to pull the rear interior panel on the driver's side. When I was pulling the rear harness back there I noticed that it would be real easy to run the harness through the rear window track instead of behind it. If the previous owner wasn't careful or just pulled the wires through without removing that panel a wire could very easily have gotten stripped, pinched, cut, etc.. Good luck.
Dez is offline  
Sponsored Links
Advertisement
 
Reply

Quick Reply
Message:
Options

Register Now



In order to be able to post messages on the Vintage Mustang Forums forums, you must first register.
Please enter your desired user name, your email address and other required details in the form below.

User Name:
Password
Please enter a password for your user account. Note that passwords are case-sensitive.

Password:


Confirm Password:
Email Address
Please enter a valid email address for yourself.

Email Address:
OR

Log-in










Thread Tools
Show Printable Version Show Printable Version
Email this Page Email this Page



Posting Rules  
You may post new threads
You may post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is On
Trackbacks are On
Pingbacks are On
Refbacks are Off

 
For the best viewing experience please update your browser to Google Chrome