# battery wont charge. new alt and no shorts that i can find.



## flabbymatt (Dec 6, 2009)

i have a 1990 jetta with the 1.8L 8v. recently i noticed that the battery wasnt being charged. i jumped it and charged it off my other car for a while and it started fine and ran but killed the battery. i got a new alternator and checked the lead and grounds and i cant find anything wrong with it but it still wont charge the battery. i even started it and disconnected the + lead on the battery....car died. i also noticed that the battery light wasnt coming on with the ignition like i thought it should. any help?


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## TheMajic86GTI (Aug 9, 2009)

*Re: battery wont charge. new alt and no shorts that i can find. (flabbymatt)*

Double check ur grounds and fuses...also the OEM power wires have a fuse inline built into them(looks like a piece of plastic just before the battery connections) check ur power wire with a volt meter to make sure...


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## flabbymatt (Dec 6, 2009)

*Re: battery wont charge. new alt and no shorts that i can find. (TheMajic86GTI)*

i didnt see a fuse but i checked by jumping the car from the + lead on the alternator and the chassis just to make sure the power was able to go from there to the battery. it worked. maybe ill run another + wire directly to the battery just in case. (the alternator is internally regulated). it just has me kinda stumped.


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## flabbymatt (Dec 6, 2009)

*Re: battery wont charge. new alt and no shorts that i can find. (flabbymatt)*

holy crap i think it worked!! i just ran some heavy gauge wire from the alt to the battery and it has been running now for 30 min with the lights on and the blower going i also turned on the ac so the radiator fan is on. the lights havnt dimmed and it is still running fine. it took 5 min for the battery to die last time. now i just need to find out exactly what was wrong with it so i can fix it right.


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## pewpewlasers (Jun 12, 2009)

*Re: battery wont charge. new alt and no shorts that i can find. (flabbymatt)*

check your grounds sir, make sure they are solid
http://forums.vwvortex.com/zerothread?id=4675370
pics there
also take your battery to autozone and have it tested, if your alternator before went bad it could have spiked and overcharged your battery causing it to loose some water inside the battery
Autozone battery test is free, do that first then check grounds if battery is known to be good


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## TheMajic86GTI (Aug 9, 2009)

*Re: battery wont charge. new alt and no shorts that i can find. (flabbymatt)*


_Quote, originally posted by *flabbymatt* »_holy crap i think it worked!! i just ran some heavy gauge wire from the alt to the battery and it has been running now for 30 min 

I would suggest getting a new power wire like before...seems to be ur problem...and it wont hurt to clean up all ur grounds even if they look good...


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## vr2jetta (Dec 16, 2007)

*Re: battery wont charge. new alt and no shorts that i can find. (TheMajic86GTI)*

My buddies corrado has been having the same problems. Replaced the battery leads and seems to be fine now.


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## flabbymatt (Dec 6, 2009)

*Re: battery wont charge. new alt and no shorts that i can find. (vr2jetta)*

k. nvm it didnt work.







i took it to autozone and the battery is fine. double checked and cleaned all the grounds. now the battery light in the dash isnt turning on with the ignition again. stumpped. all grounds are good new wire to the battery and still wont charge it or run without the battery. maybe im just a noob but what the hell.


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## lilgreydentwagen (Sep 13, 2005)

*Re: battery wont charge. new alt and no shorts that i can find. (flabbymatt)*

there should be a small blue wire coming off the small terminal on the back of the alternator, this goes to a connector near the starter then to the back of your gague cluster somewhere and tells your battery when to charge. check to see if it has any cracks or is broken. i've had to re strip mine many times until i finally yanked it out and replaced it with a 12 gauge wire... hope this helps some


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## flabbymatt (Dec 6, 2009)

*Re: battery wont charge. new alt and no shorts that i can find. (lilgreydentwagen)*

i just checked that wire to the plug by the battery. its all fine maybe it has a short from there to the gauges. ill have to check that in the morning. and figure out where it goes and how to get to it.


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## flabbymatt (Dec 6, 2009)

*Re: battery wont charge. new alt and no shorts that i can find. (flabbymatt)*

actually, i think it is that wire. the car starts and charges every time that battery light comes on. the problem is sometimes the light comes on and sometimes it doesnt. to me that means short. and the only wire going toward the dash is that little blue one. just dumped about a foot of snow and still going so ill dig in to it when it clears up. in the mean time, anyone have any tips for tracing that wire or maybe exactly where it goes so i can just run a new wire? thanx


_Modified by flabbymatt at 4:28 PM 12-7-2009_


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## lilgreydentwagen (Sep 13, 2005)

*Re: battery wont charge. new alt and no shorts that i can find. (flabbymatt)*

i'm pretty sure it hooks into the gauge cluster. that wire is very flimsy. i could strip mine with my fingernails. i'll look in my bentley to find out for sure when i hit the shop in a few.
edit: the wire does run directly to the gauge cluster harness. i'm pretty sure it runs inside the front wiring harness somewhere towards the firewall, so what i would suggest is to pull your gauge cluster and run a continuity test between where the wire hooks to the alternator and the gauge cluster harness. if there is a break in the wire you can replace it from there. 


_Modified by lilgreydentwagen at 12:40 PM 12/8/2009_


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## flabbymatt (Dec 6, 2009)

*Re: battery wont charge. new alt and no shorts that i can find. (lilgreydentwagen)*

cool, is that wire still blue at the dash cluster? im just going to( because i dont think it can hurt) replace that wire all together. i hope it works. ill dig in tomorrow.


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## nwarner882 (Dec 2, 2009)

*Re: battery wont charge. new alt and no shorts that i can find. (flabbymatt)*

Im having the same exact problem!!! Just put a new alternator in today. I cant get it to charge the battery will run for a minute if I jump it then it will just drain the battery till it dies. I have no car right now do to this problem!


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## lilgreydentwagen (Sep 13, 2005)

*Re: battery wont charge. new alt and no shorts that i can find. (nwarner882)*

yeah it is blue all the way to the gauge cluster harness.


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## flabbymatt (Dec 6, 2009)

*Re: battery wont charge. new alt and no shorts that i can find. (lilgreydentwagen)*

i was just wondering if there are any how too's on taking the dash apart and getting to the back of the gauge cluster. i would like to know a little about it before i get in there and break something. thanks for any help.


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## TheMajic86GTI (Aug 9, 2009)

*Re: battery wont charge. new alt and no shorts that i can find. (flabbymatt)*

Its pretty easy....I havent done it in yrs but from what i remember, just pop out the dash bezel that goes around the cluster and radio(be careful on the radio side as this is where they tend to break). And there should be 4 screws holding the gauge cluster, remove screws after this i cant remember if u have to unscrew the speedo cable first from under the dash or not...then pull the cluster out....If u can remove the steering wheel it would make this alot easier but its not necessary..


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## creterunna (Feb 10, 2006)

*Re: battery wont charge. new alt and no shorts that i can find. (TheMajic86GTI)*

tearing apart the dash and cluster is a pain in the ass and theres an easier fix
.buy a 2 dollar diode at radio shack ...the band on diode marks the cathode and that end should go toward the alternator side of wire.!! this is in place of blue wire on alternaor and you can test it by tapping off the battery,if it gets battery to charge you then have to tap into a circuit that is only charged when key is on(like driving down the road...IF YOU PUT LEAVE IT DIRECTLY TO BATTERY IT WILL DRAIN BATTERY WHEN EVER IT ISNT RUNNIN i havent had any any problems but was suggested to put a resistor in the new wire as well


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## flabbymatt (Dec 6, 2009)

*Re: battery wont charge. new alt and no shorts that i can find. (creterunna)*

im a bit of a noob on things like this. can you give a little more detail on the diode install? just so i understand, get a diode(what type) connect new wire from the alt to the battery with the diode installed in the middle like you said. that should fix the problem. to make sure the battery doesnt die when the car is off, i have to then run the wire through something in the fusebox that turns on with the ignition. basically do i have it right? (sorry im a noob with electrical systems)










_Modified by flabbymatt at 4:05 PM 12-10-2009_


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## flabbymatt (Dec 6, 2009)

*Re: battery wont charge. new alt and no shorts that i can find. (flabbymatt)*

I was just thinking: that little blue wire basically tells the battery when to charge, right? wouldnt the engine still run once its started? because not only will it drain the battery when its running, the engine will die when the battery does.







. if anyone knows for sure, let me know. im about to go try to get the dash apart so i can see about replacing that wire.


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## TheMajic86GTI (Aug 9, 2009)

*Re: battery wont charge. new alt and no shorts that i can find. (flabbymatt)*

No need to take the dash apart....just find out where the wire connects behind the cluster and run a new one.......


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## flabbymatt (Dec 6, 2009)

*Re: battery wont charge. new alt and no shorts that i can find. (TheMajic86GTI)*

before i read your last post, i took the dash apart and on the back there is a flexible plastic circuit board. on that there was one wire that looked burned or broken and was fixed with another wire soldered over it. on one side the new wire was barely connected so i just traced back where the circuit went in both directions and soldered a new wire directly from the plug to the connection it led to. now every time i turn on the key, the battery light turns on. but now one or both of the fuel pumps are not working







and i broke the plug on the back of the speedo.







(probly an easy fix cause it has been broken before and glued. i just broke the glue joint.) what i want to know now is: is it as simple as checking power at the pumps to find out which is bad? i.e. if it has power and not running= bad pump and does not have power= short somewhere from there to fuse box? let me know if i got it right and any feedback anyone has to maybe make it easier.


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## nwarner882 (Dec 2, 2009)

*Re: battery wont charge. new alt and no shorts that i can find. (flabbymatt)*

dude i wired a switch today and it works perfect you should do the same. Just run a wire from your positive lead on your battery and a wire from your voltage regulator. Put a switch in your dash took me ten min. turning it on and off is a pain but does the job










_Modified by nwarner882 at 1:58 PM 12-14-2009_


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## millerspcrepair (Mar 16, 2009)

*Re: battery wont charge. new alt and no shorts that i can find. (nwarner882)*

I also Had the same issue and found out mine was under the ignition it was shorted ran a new piece of cable now i got 14.13 volts


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## flabbymatt (Dec 6, 2009)

*Re: battery wont charge. new alt and no shorts that i can find. (millerspcrepair)*

i found(after i took off the dash) a wire that had been repaired previously and it was all but broken off so i traced it back in both directions and soldered a wire from beginning to end and now it works just great.


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## BSD (Jul 8, 2008)

Yeah, with a broken "exciter wire" ( aka blue wire ) your car will only charge above 4k I believe.. I drove around like 3 days without that wire.. lotta high rpm driving.








Steve-


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## chois (May 12, 2000)

So if we have no cluster at all, and no exciter wire destination, just put a diode between the exciter and a switched 12v source correct?


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## creterunna (Feb 10, 2006)

*Re: (chois)*

CORRECT ALTHOUGH SOME GURUS SUGGEST A RESISTOR BUT i havent burnt my alternator up yet


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## creterunna (Feb 10, 2006)

*Re: (creterunna)*

make sure the band on diode(cathode end)is on the alternator side/direction










_Modified by creterunna at 8:24 PM 12-20-2009_


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## millerspcrepair (Mar 16, 2009)

*Re: (creterunna)*

wont this have a constant 12v to the alternator and eventually kill the battery Cause the exciter wire goes to the ignition which only pushes 12v when ignition is on.


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## chickenfriend (Jan 31, 2005)

*Re: (millerspcrepair)*

All these alternator problems exciter circuit problems have an easy, temporary fix.
Use an 18 gauge wire, solder in a 24 ohm resistor somewhere in it. Hook one end to the coil + (usually there is a 3rd unused spade on the terminal tree), and hook the other end to the exciter terminal on the alternator. Done.
Using this arrangement, the exciter circuit will not be able to discharge the battery, since the + coil terminal is on the #15 power track (switched-on). This wire will also provide a small, controlled current (1/2 amp) to the pre-exciter circuit, which should be enough to allow electromagnetism to develop in the rotor.
When you have time, check the stock wire from the alternator to the instrument cluster plug for continuity. If the wire is ok, then the problem is either a burned-out LED light, or the defective in-series resistor.




_Modified by chickenfriend at 7:05 AM 12-21-2009_


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## chois (May 12, 2000)

Thanks for the info. I have been just blipping the rpms enough to get it charging when I started it (which is like 6k with the underdrive pullys). It has definitely continued to charge thereafter, but I never like giving that much rpm before it is fully warmed up.


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## jerseyrider (May 28, 2006)

*Re: battery wont charge. new alt and no shorts that i can find. (TheMajic86GTI)*

ok, I think I get it... Blue wire=Evil. Replace it with a purple one!







So I'm confused because this dead battery seems to be killing my engine... I'm running a diesel. I've had the battery die before, Still made it to work (though I don't suggest driving at 5am with no headlights). Why would this cause my engine to die?
Thanks


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## JoggerNot (Nov 6, 2009)

Short :x


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## TheMajic86GTI (Aug 9, 2009)

*Re: battery wont charge. new alt and no shorts that i can find. (jerseyrider)*


_Quote, originally posted by *jerseyrider* »_ So I'm confused because this dead battery seems to be killing my engine... Why would this cause my engine to die?

If ur battery is dead and ur motor shuts off is because u have a faulty alternator or bad wiring to it...You can take the alternator to any autozone or advanced auto parts and they will bench test it for free..If its good then u know u have bad wiring...


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