Battery/Electrical Problem
 

Hello - I have a serious problem and am not sure even where to begin troubleshooting...It seems that when I leave the battery connected overnight - it is dead or close by the next morning. I have had this for a while and usually just disconnect it after driving the car for the day. If I leave it connected it seems to drain over night so something is eating the charge. It is a new battery and works great when the car is in use. The alternator is working too because I can run all accessories without the battery when the car is running (lights, Etc.) My ampmeter shows about 16 when running the car and about 12-14 when it is off. The next morning it shows way low and the started just clicks when I try to start it. Other than putting in a Switch to disconnect power after I stop the car...How-where do I even begin to track this down. I have no Idea where to start. I do have a meter to use, but don't know where to begin????

Just for those of you that have read the U-Joint porblem I posted a week ago...I have the new ones on and from the first run - it seems OK. It must have been the old U-Joints that were causing the problem. I am still not satisfied with the spring though! I might put the original ones back on - still thinking about it.

TJ

Had the same problem with my 68 while I was restoring it. Spent 6 months trying to troubleshoot where the short was (suspected it was near the solenoid) but never could figure it out. Battery would be dead in 2 days whenever I left it hooked up. Harness must've been spliced or jimmy-rigged in about 30 places and looked like crap. Finally I said screw it and replaced all the wiring from the dash to the alternator with new reproduction ones and it solved all my problems. Expensive though - cost me $175 for the main harness, $25 for the headlight leads, and another $25 for the alternator harness ($225 total). Since I had already restored the engine compartment, it also finished it off looks-wise to near perfect original condition. I didn't have any experience with electrical work or any friends who could help, so this was simplest solution for me. If replacement isn't an option, I'd unplug from the dash, remove, unwrap the entire harness, carefully inspect for any breaks, repair, and re-wrap with new electrical tape. That's what I did with my underdash wiring. That one was too expensive for me to replace (about $650 for a new repro).

Your alternator can run the car with good voltage and just a few amps. Flip your meter to amps, and check. Don't know what amp your alt is but it probably 60 amps or better.

Disconnect the negitive battery cable and put a test light between the cable and the battery. If the test light is on, there is a draw somewhere on the battery. That would drain your battery. If the lights on, go to the fuse box and remove one fuse at a time until the light goes out. Remember-your door open may cause the light to turn on. So shut the door each time. Maybe you'll find a simple switch bad.

Door switches, glove box switches etc can jam closed and cause a draw.

Do check all of the battery connections, remove sand/clean/replace and test.

Good luck.

I will start with the simple areas
 

Thanks for the advice - I think I will start with the door jambs and such first and see if I can rule out the obvious. It sounds like good advise before I replace the wiring (although it is in the plans for next winter). Thanks for the tip about the negative wire suggestion...If i do the test and I get no current with the negative removed and the meter between them does that mean there is not a draw. Should I do this with the car running and not running. What would be the next step if the test proves negative and there is not a draw. You guys should charge for this advise...It is very helpful
Thanks again!

On to Step #2
 

OK - I tested the negative cable and put a meter between it and the negative post on the battery...Serious charge between the two. I then removed all the fuses - re-tested - still a serious charge. There is something taking power. Where should I check next and how should I do it. We are starting to eliminate possible causes and with your help maybe we can get it.....

TJ

Try unpluging different things. Wiggle your ignition switch, unplug alt, check/clean ground strap, starter cable etc. Just keep unplugging until it goes out.

How many amps is your alternator putting out? Could be shorted, but still keep car running.

Will keep trying
 

The alternator is 65 amps. I will try unplugging things as I go along. My wiring is such a mess that it might come down to just replacing it all in the end, but I want to avoid that if at all possible.
I will let you know what I find...
TJ

If you are still getting a draw whith all the fuses out, start checking the systems that have constant power. Ignition switch, horn ,hazards etc. It could be the harness, but if it visually looks good chances are its not bad and just grounding somewhere. I had this problem for a long time, and I did install a cutoff until I found it. How is the under hood harness, charred, dried out? Mine got mangled in a fire, replaced and I still and a draw on the battery. I finally tracked it down to a faulty horn switch, it was grounding to the steering colum. If you dont have one already get a wiring diagram. You can cross things off as you go along. You'd be surprised on what systems are wired together too! That a test light, and does your volt tester check for continuity? That comes in handy too. Take your time and keep track of what you've illiminated. There are only so many systems on an old mustang, you'll track it down. Just be glad it's not one of these new ones with 10,000 wires!

Still Looking....
 

Thanks for all the great advise...Maybe 10,000 Good wires would be better than 100 bad ones :)

I removed the starter and the alternator and tested again - Still a draw. I then unplugged the 2 wiring harnesses from the firewall and tested...still a draw. Do I need to start ripping the wires inside apart. I thought by disconnecting the 2 plug in's that I would get a "no-Draw" reading? I am really confused at this point.

Note on the drive shaft....New U-Joints worked like a charm! I might even keep the springs...It really runs on the highway with the new tranny and all the mods this winter. Bring them rice rockets on! (oops - My Girlfriend drives a Honda) Sorry!

You'd be surprised on what systems are hooked together. Get a wiring diagram so you can trace them back to origin. there are a few harnesses that pass through the firewall. The biggest is the main harness or headlight harness. The wiper harness, neutral saftey switch harness, and the ignition harness also go through. If, I'm not mistaken. Things like a convertable have a straight line to the starter solinoid and dont go through the firewall. It's a real pain but unless the harnesses look damaged I wouldn't go cutting them open yet. Hang in there

Problem Corrected
 

Don't ask me how I found it, but I was just fooling around with the wiring and I found a black wire that was not connected to anything. After messing with it for some time - I stumbled on the fact that if I grounded it to the negative terminal on the battery the drain on the battery went away. I must have missed this one when the engine was installed. Since it was a 6 cylinder car originally - there were some wires that were not used. I tested all the other connections and the battery now holds a charge and all accessories work fine. What a find....The tip on checking the negative terminal removed from the battery saved this project.
Thanks a Bunch!!!
TJ

Here we go again
 

Well - I spoke too soon. Got home from work and the battery was dead. I tested the negative again and looks OK so I did the same for the positive - removed the cable from the battery and tested from positive cable to battery and it was active. Is this OK or do I now have another problem??? Not sure if I can test the positive in the same way as I tested the negative? Back to the drawing board.....
TJ

If the test light is off, you have no draw. Its in the charging system.

Im thinking your alternator and or regulator is bad, or your battery. The alt should be putting out 13.5-14.5 volts running with 65 amp also. 12.6 or so with the motor off. The car can run with considerable less volts or amps and not charge fully. But if the alt is not putting out those volts or amps, its bad. Auto zone checks charging systems for free.

What I did
 

These cars are negative ground. If there is a current between the + battery cable and the + battery terminal as detected by a test light with the cable removed from the battery (engine off, ignition off, doors closed), then there is a short somewhere (that's with the ignition off and the doors closed).

What I did after dectecting the short was to check each wire that goes to the starter relay that the
+cable goes to. Check these wires one at a time with them all disconnected from the starter relay using the test light to see which wire leads to the short (use the test light between the wire and starter relay terminal). The one that lights it up tells you which area the short is in. Mine was in an aftermarket relay to the auxillary electric fan.

Yours could be in any circuit, but you'll know which one by which wire lights the test light. After determining which circuit, youl'll need to follow up the branches of that circuit to find the actual short. There should likely be a frayed or burnt wire somewhere. When you find it, consider making sure there is a fuse or circuit breaker somewhere in that circuit.

I hope I am making sense here.

Rev

I will keep trying
 

Rev - that makes perfect sense. That is my next project - to do just that. Just to clarify the problem as it is now...with the postiive cable removed from the battery and the negative attached - when I put the light (I am using a meter) between the positive terminal on the battery and the positive cable - there IS a charge present. Same as did exist in the negative terninal where this problem started. I purchased a battery cutoff switch and am planning on installing that (even if I find the short) but in the mean time it will allow me to enjoy the summer without worring about a dead battery at the grocery store. I hope these latest test lead to the cause of the problem. I have my work cut out for me. Seems like just one thing after another. I really wish now that I would have taken the entire car apart and done it right from the beginning. Thanks again!
TJ