Electrical 65 Alternator Dash Light Problems

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Whats the problem? Light flickering on at low rpm?
Wish it was that simple......my charge indicator light socket has 12 volts going to both wires in bulb socket.......light doesnt come on when I turn the key in the on position or when I start the car.......new alternator....Its stumping me.....I have traced the green wire with red stripe from the bulb socket that is suppose to be ground all the way under the dash to the main harness connector on the cowl.......non I go out o the engine side and unplug it ......it is not hot........when I t in the harness that's when the ground wire becomes hot.........I traced the same green wire with red stripe on the engine side of the main harness and it goes to the voltage regulator.....it is not hot....but when I pug the main harness together.....that's when it becomes hot and makes the green wire with red stripe hot it shouldn't be.....so with all that said I am not one to just go by parts by guessing...I have always tried to figure out the problem then buy the part......at this point I am thinking the voltage regulator has shorted out even though its not that old and sending current where it shouldn't.......I am getting 14 volts at the alternator and its not really decreasing......I appreciate youre responsebut this may not be a simple answer like you expected.....I am open for any responses or thoughts on this before I go buy a what is only a 30 dollar part......
 
Yeah that's a tuff one. When you are testing the ground side of the socket is the bulb installed? Have you done any rewiring of the ignition switch or anywhere else recently?
I have had bad luck with new regulators. They all seem to come from China now and just don't work well. I put my old original regulator back in and everything works great now.
Does everything else work good? Blowing any fuses?
 
The only wiring diagram I have for 65 shows charge light with yellow and black stripe wire and black with green stripe.
Is this a GT or 64 1/2 (which had a generator) that possibly was converted for alternator?
 
Ok found another diagram with your color coding.
Looks like maybe your regulator provides your ground for you which if its not working right wont provide that grnd? What kind of voltage are you showing at the battery with the engine running?
 
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Ok found another diagram with your color coding.
Looks like maybe your regulator provides your ground for you which if its not working right wont provide that grnd? What kind of voltage are you showing at the battery with the engine running?
WOW!!!...I think I found the right person that's for sure!...Let me answer one question at a time....First of all I havnt checked the wires with the bulb installed...I will in a few minutes...just got home and am ready to try a few things...second..I unplugged the ignition switch to put a new bezel on...that's about it other than a few harnesses and Ive triple checked them.....I am having a fuel gauge problem that is giving me fits but I need to figure this out first because this may be related to my other problem....next...No...not blowing any fuses.....next.....Yes it is a yellow and black wire and a green with red stripe....I hate to say but Im not sure on the year but im 98 percent sure its an early 65......I don't think its been converted to a alternator......and lastly I am getting a solid 14 volts to the alternator...doesn't seem to go down which gives me a sign of a bad voltage regulator....and that is where im at...I am wondering if the regulator is bad and backfeeding or doing something stupid causing my problem....I REALLY appreciate the input...its nice talking to someone that doesn't say all the easy stuff....Who doesn't check that first?....so im gonna go check that bulb in the socket and get back to ya....My name is Nick. I'll get back to ya in a bit.....
 
WOW!!!...I think I found the right person that's for sure!...Let me answer one question at a time....First of all I havnt checked the wires with the bulb installed...I will in a few minutes...just got home and am ready to try a few things...second..I unplugged the ignition switch to put a new bezel on...that's about it other than a few harnesses and Ive triple checked them.....I am having a fuel gauge problem that is giving me fits but I need to figure this out first because this may be related to my other problem....next...No...not blowing any fuses.....next.....Yes it is a yellow and black wire and a green with red stripe....I hate to say but Im not sure on the year but im 98 percent sure its an early 65......I don't think its been converted to a alternator......and lastly I am getting a solid 14 volts to the alternator...doesn't seem to go down which gives me a sign of a bad voltage regulator....and that is where im at...I am wondering if the regulator is bad and backfeeding or doing something stupid causing my problem....I REALLY appreciate the input...its nice talking to someone that doesn't say all the easy stuff....Who doesn't check that first?....so im gonna go check that bulb in the socket and get back to ya....My name is Nick. I'll get back to ya in a bit.....
OK....Heres what I got...I started the car and put the bulb in the socket and used a test light on the wires coming out of the back of the socket...when I stuck the hot wire it was hot as I expected and when I stuck the ground...the green with red stripe wire it lit the bulb but it was dim???..and I didn't blow a fuse?? I used a volt meter directly on the hot on the back of the alternator and grounded directly on the casing and got 14 plus volts....Im gonna let it run for a few minutes and recheck it and get back with ya......so I don't want to suggest anything but I am REALLY leaning towards a new voltage regulator but I would like to hear what you think my friend...Nick
 
OK....Heres what I got...I started the car and put the bulb in the socket and used a test light on the wires coming out of the back of the socket...when I stuck the hot wire it was hot as I expected and when I stuck the ground...the green with red stripe wire it lit the bulb but it was dim???..and I didn't blow a fuse?? I used a volt meter directly on the hot on the back of the alternator and grounded directly on the casing and got 14 plus volts....Im gonna let it run for a few minutes and recheck it and get back with ya......so I don't want to suggest anything but I am REALLY leaning towards a new voltage regulator but I would like to hear what you think my friend...Nick
I know I threw a lot back at ya but I wanted to let ya know I ran it and it stayed at 14.15 volts so I shut it off...let it sit for a while and rechecked the battery with the ground wire off and it had 12.77 volts in it.....
 
So that tells me that your not receiving a proper ground for that bulb and your tester provided somewhat of a ground.
Make sure your voltage regulator is grounded properly. There should be an individual black wire grounding the regulator casing to the frame and to the ground post on the alternator. You can do a continuity test from case of reg to ground on the frame or eng block and then from reg casing to ground post on alternator. You should get a good indication of a ground on all of these tests. If not follow that ground wire from the regulator to the grounding terminal.
Just for giggles when you get a chance, start it up and see what the voltage is at the battery posts. I just want to see what is actually showing at the battery. Your test on the back of the alternator shows that it is working (at the alternator) but not what actually makes it to the battery.
You may have more than one issue here. I concerned about you getting voltage out of your ground wire. The voltage reg could possibly fix that and the grounding issue but you could be feeding power into your ground from another source. Try testing other ground wires to see if you are getting anything voltage wise thru them too.
Another just for giggles test - with the engine running take your tester from the casing of the alternator to the battery neg post and see if you get any voltage.
Also make sure your ground strap from your engine is installed and tight, this is the one that runs from your block or a head and grounds to the frame (usually on the back of the engine to the firewall). You need to have a good ground from the block to the frame in addition to the battery neg post to the block. Make sure of this before you replace anything.
 
So that tells me that your not receiving a proper ground for that bulb and your tester provided somewhat of a ground.
Make sure your voltage regulator is grounded properly. There should be an individual black wire grounding the regulator casing to the frame and to the ground post on the alternator. You can do a continuity test from case of reg to ground on the frame or eng block and then from reg casing to ground post on alternator. You should get a good indication of a ground on all of these tests. If not follow that ground wire from the regulator to the grounding terminal.
Just for giggles when you get a chance, start it up and see what the voltage is at the battery posts. I just want to see what is actually showing at the battery. Your test on the back of the alternator shows that it is working (at the alternator) but not what actually makes it to the battery.
You may have more than one issue here. I concerned about you getting voltage out of your ground wire. The voltage reg could possibly fix that and the grounding issue but you could be feeding power into your ground from another source. Try testing other ground wires to see if you are getting anything voltage wise thru them too.
Another just for giggles test - with the engine running take your tester from the casing of the alternator to the battery neg post and see if you get any voltage.
Also make sure your ground strap from your engine is installed and tight, this is the one that runs from your block or a head and grounds to the frame (usually on the back of the engine to the firewall). You need to have a good ground from the block to the frame in addition to the battery neg post to the block. Make sure of this before you replace anything.
Guess I failed to mention that when I also test the voltage going to the battery post from the alternator is the same as directly coming out of my alternator....14.15 volts......I'll go ahead and do the casing test but as far as my engine to firewall ground....good.......ground wire connection that bolts to the voltage regulator casing.....good....everything is cleaned or new.....thanks for the new info and i'll get back with ya this afternoon on the casing test..Nick
 
Guess I failed to mention that when I also test the voltage going to the battery post from the alternator is the same as directly coming out of my alternator....14.15 volts......I'll go ahead and do the casing test but as far as my engine to firewall ground....good.......ground wire connection that bolts to the voltage regulator casing.....good....everything is cleaned or new.....thanks for the new info and i'll get back with ya this afternoon on the casing test..Nick
OK..UPDATE!........I checked the alternator casing with the red lead on the casing and the black lead on the negative post on the battery and go nothing........so....I went with my gut and bought a voltage regulator and as I expected it was bad ...I THINK........so the charge indicator light did come on with the key in the on position and when I started it the light went off but I noticed it was dim???....ssoooooo.....I checked voltage on the socket with the key on and before I installed the new regulator and I had almost 14 volts on both terminals inside the bulb socket........then after I installed the regulator like I said the light came on and went off but with the bub out of the socket instead of 14 volts on both terminals I had 14 on the green with red stripe wire which is the center terminal and only 4.50 volts on the yellow with black stripe.....I don't think that there should be any voltage on that wire should there?....now I th....ink I am getting close but I am no sure what to do at this point....Thoughts Please....Thanks.....we are getting there
 
OK..UPDATE!........I checked the alternator casing with the red lead on the casing and the black lead on the negative post on the battery and go nothing........so....I went with my gut and bought a voltage regulator and as I expected it was bad ...I THINK........so the charge indicator light did come on with the key in the on position and when I started it the light went off but I noticed it was dim???....ssoooooo.....I checked voltage on the socket with the key on and before I installed the new regulator and I had almost 14 volts on both terminals inside the bulb socket........then after I installed the regulator like I said the light came on and went off but with the bub out of the socket instead of 14 volts on both terminals I had 14 on the green with red stripe wire which is the center terminal and only 4.50 volts on the yellow with black stripe.....I don't think that there should be any voltage on that wire should there?....now I th....ink I am getting close but I am no sure what to do at this point....Thoughts Please....Thanks.....we are getting there
OK ...one other thing I found...as far as the alternator dash light im gonna say its fixed unless you think different about it being dim..I am getting 14.40 volts at the battery but I don't think its overcharging is it?..........so the other problem found tonight was I was checking my lights all and everything worked but I noticed that when I turned my running lights or parking lights on they worked fine but when I turn the headlights on the parking lights go out....turn signals work with the lights on....anyway I havnt checked the diagram out yet ...I thought I would throw that at ya since it just came up and get your thoughts...Thanks for the input
 
Your front parking lights are working correctly for a 65/66 Mustang. They go out when the headlights are on-that is the way they were originally designed.

The turn signals should always work with the key on.
Boy I feel stupid!...I've owned a few of these but this is the most I have gotten in to one.......I know the turn signals are suppose to work with the key on I guess what I was saying was that related to my problem which wasn't a problem......I was just looking at the schematic before I went out there....You save me some time....I guess after this charge light issue and fuel gauge issue I was thinking something else was wrong!!....Do you think I should further into the charge light issue or let it go? Thanks Dennis