Thread: Electrical Problem

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I have been having ongoing electrical problems with my '69 Mustang and have taken it to 2 mechanics who have been no help. The problem is simply that the battery will not charge. I have done pretty much everything: replaced the alternator twice, replaced the regulator, starter coil, starter relay, solenoid, battery, connections to battery.
At idle speed, there is about 10 volts coming into the battery (about 14 are needed), and at 2500 rpm, this rises to 12.5 volts -- the car turns off when the cable is disconected from the negative terminal.
I have absolutely no idea what is wrong because I have replaced everything that needs to be replaced. Does anyone know what could be wrong?

If all the components are known to be good, the problem must be in the wiring harness or a bad connection / ground somewhere.

pro is right make sure you have 12v at the reg.

I would also try a second regulator. My wife's 66 mustang had the same problem a while back and I went through the same thing. The first thing I changed was the regulator but that didn't help so I had the alternator checked and it was bad. I put the new alternator in and it still would not hold a charge. What had happened was the bad alternator had fried the new regulator. I put in a second regulator and it's been fine so far.
I also went around and cleaned up all the ground connections while I was at it anyway.

I'm just talking off the top of my head here, but I think csf is on the right track. On older alternator systems with external regulators, and some of the early internally regulated alternators, there is a wire about 18 gauge that carries "exciting" current from the ignition switch to the regulator and/or the alternator. This 12 volt source "excites" the windings in the regulator and/or alternator, allowing the alternator to develop full output voltage. If this wire is bad, eg: bad connection, broken, etc., the alternator will not put out full voltage. Get a good wiring diagram for your specific year and model, and take a good look at the system. Or, find an "OLD" guy mechanic who has seen this sort of thing in his experience; a lot of guys in the trade who are under thirty, probably don't know much about this system, because it was old tech by the time they started working on cars.

gemcleod those systems are not easy to fix when you have the right tools, so it hard to tell you much on here without seeing what you have hindsight it would have been cheaper to bolt a 1 wire gm alt on there and forget about it. might still be the way to go.

Originally posted by Streets
Oh Garsch, a GM alternator on a Ford mustnag??

sounds about right. if he cant fix it or find somebody to fix it he might have to. garsch you bring it to va. i can fix it.

Originally posted by csf03716
that pretty much was what i have read, and been told by my mentor....now if we could get "Mr. Rustang" to concur, this might prevent gemcleod from spending any more un-necessary money, and loss of hair, and worse, crossbreedin his car w/a gm altenator...how absurd!....gemcleod RUN, don't walk to the autozone and get a cole-heerse replacement ignition switch for your Furd....and keep your Furd all Furd!.....

putting that ign switch on there is not going to fix it eather. if it was the switch there would be some other problems other than alt. he wonted to fix his car and not being there to check it out, a one wire alt will fix his car other wise he can keep spending money on it or carry it to a shop and pay somebody to fix it i dont care if it never get it fixed . and csf you dame sure dont know thats wrong with it.

Make sure all the grounds are clean and tight, especially engine to frame/body and neg. cable to frame/body or engine.

Jerry...

Originally posted by csf03716
thanks bill...and now some gifts for our parting

contestants...........

I SAID HINDSIGHT, BEFORE HE SPENT ALL THAT MONEY IT MIGHT HAVE BEEN THE WAY TO GO.
just because bill says its the ign switch or headlight switch dont make it so. what does gemcleod say and when did you start listening to streets? he has 3 choices, #1 keep spending money like you said. #2 carry it to a shop and get it fixed or #3 bolt a 1 wire alt on it and be done with it. it sounds like a wiring problem but i cant, you cant and bill cant tell him whats wrong with that car over the inter-net with the info we have.
thanks alot bill. you kinda pinned it down a little, you are right if it not the alternator twice, the regulator, starter coil, starter relay, solenoid, battery, connections to battery, then i guess it could be the ign. switch, headlight, or wiring harness. id start with the harness.

I will try the ignition switch suggestion -- although I am surprised that the car can turn if the problem is ignition related.
I have gone through 2 alternators and 2 regulators so far, although the previous comment that they could be burning one another out could be an explaination.
Also, two mechanics have told me that many of the alternators and regulators they are putting out these days are faulty (especially Bosch ones, which is the brand I have). However, I find it difficult to believe that 2 in a row would be duds.

Originally posted by gemcleod
I will try the ignition switch suggestion -- although I am surprised that the car can turn if the problem is ignition related.
I have gone through 2 alternators and 2 regulators so far, although the previous comment that they could be burning one another out could be an explaination.
Also, two mechanics have told me that many of the alternators and regulators they are putting out these days are faulty (especially Bosch ones, which is the brand I have). However, I find it difficult to believe that 2 in a row would be duds.

gemcleod, does the car have a volt meter on it or just a light? the volt meter could cause that. with a auto. it could be anything but ive been doing this a long time and i never fixed a charging problem with a ign. switch. if its not the bat. reg., or alt then its probably going to be in the waring harness somewhere. thanks

Since everybody is thinking off the top of there heads. Me included, WOW what a head rush. Anyway, Just a thought. Might want to check your pullies. If they were changed. maybe the alt. isn't putting out the full charge.

Originally posted by mrmustang
Let's think about this one...........Bill's handle is mrmustang , he has personally owned well over 100 Mustangs (114 to date), has restored far too many others to list.......If I state it's the ignition switch (since all main power from the alternator/charging system runs through it), then you can just about bet that it is the ignition switch. Since the ignition switch and headlight switch are fairly inexpensive, I suggest replacing both at the same time. Lastly, the wiring harness in the 1969 Mustang is of it's own unique design and layout (meaning it does not interchange with the 1970 Mustang), as is a good majority of the 1969 Mustang as a whole (mechanically speaking), going to a Mustang parts house instead of the local auto parts store will net you a better replacement piece. Once again, just my advice based on 30+ years of working on these specific



Bill S.

i agree with the ign wiring being the main power and the same wires that runs the alt. runs other stuff. the other stuff works ok. ???????????????????? and if yrs got anything to do with it i got you by about 15.

Originally posted by csf03716
good choice! that i never ever take a position on something unless i would do the same to one of my own vehicles...i will not post an answer ( to any serious problem where money or safety is involved) just to start a "PISSIN" contest.....

csf you are not qualified to be giving anybody advice about how to fix a car and thats the problem with this fourm. the people asking the ? dont know whether the person giving the answer have any idea what hes talking about or not. i dont know what you do for a living but ill make you a deal, you go over there to that forum and answer ? about something you know something about and ill stay here and do the best i can. you give answers about what happened to your car, i answer ? about what happened to thousands of my coutomer cars. thats called experience. i didnt start this pissin constest you did when you said a answer i gave was absurd, you wouldnt know weather it was or not