67 Mustang Electrical Problem

[z3r0c00l]

I have a 67 Mustang which I recently bought as a daily driver project. I now have the Mustang on the road (inspected and all) however I have an electrical problem where something is drawing about 3.3 amps draining the battery very quickly. My workaround is to disconnect the cables at this point.

I’ve done the following and have a multi-meter:

• New solenoid – needed one anyhow as the old solenoid was failing. Tested it – no problems
• New Voltage Regulator. The old VR was not supplying charge. If I pull the VR the amps go to 0. But I’m not sure this is telling me much.
• Checked battery cables for good connection. Cleaned all connections at the starter, block and battery.
• Pulled the harness at the rear lights – still shows the amp draw
• Pulled horn – still shows a draw. BTW – if I beep the horn sparks fly and I can smell wire burning. I know something is wrong here. I think the horn is also connected to the headlamp switch? If I beep the horn the headlights go out. This is something new and possibly caused by my tinkering trying to find the root of the problem.
• Pulled the headlamp switch – still shows a draw.
• Pulled all fuses – still shows a draw
• Tested with the alternator not connected – still shows a draw
• Not sure what to do next. I have a sneaky feeling the headlamp switch could be the culprit but really have no direct proof. I know some of the wires to the headlamp harness were loose and one wire was not connected. I reconnected and still see the issue.

Any ideas on next steps?

Thanks,

Patrick

 

[67GTFB]

ouch .... did you have this problem with the old regulator?? .... the fact that the drain goes away when the regulator is disconnected is curious as the headlights/ignition/etc are powered by a parallel, but separate circuit (#37) .... #152 goes to the regulator and is joined with #37 at the starter relay .... if you disconnect the regulator and the rest of the wiring is connected and the drain stops - seems to me that your problem is associated with that part of the wiring ..... the only circuit that goes to the regulator that is tied to circuit #37 (that's the battery feed to the dash that powers the fuse panel too) is that "#904 wire that is the ignition "on" input to the regulator from the ign switch .... with the regulator plug disconnected, does everything work the way it should? .... if so, then I'd focus on the regulator, it's internal wiring and perhaps how the contacts are designated - are they the exact same as the original harness?? .... this probably doesn't help much .... good luck ....

 

[BarnStang]

Hmmm, good one. The horn problem may simply be that the horns are really old and drawing more current than they should to work...may want to try some new horns there. You "may" see small contact flashes at the horn button...you're switching 12v through the contact plate in the stock configuration. But if you smell burning than you should look at that closer. You can do a simple test, get some 12 or 14 gauge wire and jumper from the battery + right to the horn 12v terminal and see how warm the wire gets. If it gets hot fast, it's the horn. Pull the wires from both horns and test seperately.
Why would it make the headlights go out? If it goes through the same fuse, and I think it does, I have some suggestions. It may solve some other things, but not the current draw, I was betting on the alt for sure, but if you pull the plug on the alt harness and still have the draw...need to think about that one. Here are some thoughts I have posted before:
I have run into problems with the fuse box on these cars when refurbishing the harnesses. I ran an intermitant problem down for over two hours on the dash lights. First, if you have never done it, pull ALL the fuses, pitch them, and get correct replacements. I have found fuses that looked perfect till I pryed it out and the cap fell off the end in my hand...I could see where the filiment had disintegrated at the cap end. Would pass continuity with a meter, but not heavy current draw from the circuit. Oh, make sure you scrape the fuse holders with something if rusted. I tape over the lettering, put the fuse box in the media cabinate and close the door over the harness, and dust off the contacts wth abrasive media-enough to get the rust off.
THe same identical problem, but this time it turned out to be the wire crimped to the fuse holder on the back of the fuse box. The wire had rusted just enough inside the crimp to pass continuity with a meter but not with a load.
You will need to look at the condition of the fuse box and wiring to decide if any of this is possibly contributing to your problems.
As for the VR, if you got a new one, it should be an electronic replacement and will no longer have contacts, so should be pretty bullit proof. As suggested, make absolutly certain the wires are in the right place in the VR connector. Sometimes this part of the harness is really butchered up for some reason...lastly, if the noise suppression condensor is still there and actually clamped in place, it may be shorted to ground, and causing the draw, but it seems remote. Something to check.

 

[Rusty67]

Barnstang, I know the reason that harness gets butchered. Its those f****ing haynes manuals. The wiring diagram that is listed in there is wrong and people get WAY confused. The connector is wired differently depending if you have an ammeter or an idiot light for battery charge. They only list the one for the idiot light. This screwed me up on my 67 when I first got it.... my dad hacked the crap out of the harness after we had an hour long argument. Turns out I was right and he just blindly followed the wrong diagram in that stupid haynes manual. Then he forced me to take it to a "pro" who charged me almost 600 bux for a REALLY bad patch job. Not that I'm bitter or anything. Lets just say my dad doesn't work on any of my cars at all EVER anymore.

As for the drain on the battery.... I'd take the VR back and tell them they sold you a bunk one. Put the new on in and see if you have the same problem. If you have all the fuses out an the VR in and there is a draw then disconnect the VR and the draw disappears then either you have a bad VR or you have a short in the wires between the fuse box and the VR connector.

 

[67rcks]

try to pull underdash connectors and pushing back in looking at the amp meter and go from there. If you pull all of them and still there is short go towards the battery. Use ohmmeter to see whether there is any resistance btw any suspected wire and BARE METAL ground with battery disconnected.

I assume your ign switch is in off position.

With horns, I guess the smell comes from the steering wheel right in front of your nose and contacts are probably worn. it is unlikely they would touch ground in that area.

 

[z3r0c00l]

Good stuff

Thanks for all the replies - I'll try these suggestions and see if I can get this thing figured out.

Again - thanks

Patrick

 

[347mustang1967]

i had that trouble with my horn too, i figured out the problem was that the spring inside was touching some metal causing it to spark i fixed this my putting electrical tape on the bottem and the top of the spring this solved the problem clean and simple give that a shot

 

[z3r0c00l]

Voltage Regulator - darn

It was the Voltage Regulator.

I had actually put two VR's in the car prior to starting this thread and so that's why I had not felt like the VR was the problem.

Yesterday I went out and bought a new VR (Higher Quality) and what do you know? Blamo - no drain.

Friggin a.

I spent about 2 months trying to track this sucker down.

Thanks for all your comments. This helped me track down the issue.

Now on to figuring out how to lower the front end. The way the car sits, it looks like I'm carrying a cow in the trunk.