View Full Version : battery charging problem from hell

12-18-2010, 04:30 PM
hey guys i just finished my 185 swap into my 165. i finally got it registered and insured. but the day i put it on the roads, i was driving to my girlfriends (who by the way doubted i would ever fiunish the car :P) it died on me! it was night time and the lights dimmed and the car started sputtering. i pulled out my handy jumper box and jumped the car. it worked. but as soon as i oulled the jumper cables off the lights dimmed back down and the car slowly died. i called my friend and he brought me a fully charged die hard battery and it got me home just fine. well back to the drawing board.

i figured my alternator went bad because when i put a voltmeter to the positive and negative post of the battery it read 12.55(new battery) when i started the car it didnt go up.

when the car was off, i measured the volts the alternator post was giving off. it measured exactly the same as the battery, so i knew i had a good connection coming from the alternator power post and the battery. so ive canceled out that possibility.

when the car was running, i measured the power post again, and it only read 12.9. i figured i needed a new alternator. i went to autozone and got a reman duralast. i tried it but still got the same problem. everyone told me duralast was a bad brand to go with. well i took the new duralast alternator and my old one to autozone to get them tested....they both passed. wierd huh? i returned the duralast alternator and ordered a brand new one from napa auto parts. its a bosch alternator. well, i put it in and STILL not charging. i disconnected the power post wire on the alternator and took a volt reading from just the post with nothing attached to it. it only read 1.9volts. also, even with the new alternator in when i put the voltmeter to the posiotive and negative posts on the battery, it never went up...

SO, with all these tests and 2 brand new alternators ive come to the conclusion that the alternator itself isnt the problem.

heres my theory: someone referred to the "exciter" wire as an F wire. basically the wire that tells the alternator what to do. i have a theory that theres a missing section of that wire. heres a few tips thatll help us solve the mystery

1)the key starter does not work, i had to make my own and wired the starter to a toggle switch. now somehow the key ignition deals with the alternator. i saw on a diagram that one of the wires that go to the voltage regulator plug (on the alternator) goes thru the ignition key first... i have a theory that the reason why my alternator isnt working, is because my ignition isnt working.

this is the diagram ive been referring to

now in reference to the circular plug on the top on the diagram, youll see that prong 1 is on the top, 2 is bottom left and 3 is bottom right.

prong 1 i got a signal from even if the car was off
prong 2 i got a signal from only when the car was running
prong 3 i did NOT get any signal from, whether the car was off or on,

now back to my theory of a missing link somewhere between the fuse box and the alternator plug (oh and yes all my fuses are good). ok so inside the cabin, down by the clutch pedal theres a 2 prong plug thats just chillin and not plugged into anything, as seen below

that plug i believe is coming from the fusebox since it uses the same gauge and same color wire...

what i still need to do:see if that unknown plug is giving a voltage. if it does, one by one pull fuses and see which one that plug belongs to...
oh and also someone told me its possible that the ecu is bad. so i also need to findout which wire goes from the ecu to the alternator and test if its putting out the right amount of volts from the ecu, and downstream at the plug.

any sort of input or theory would be greatly appreciated...i didnt get the car registered and insured so it can just sit in the street...i wanna drive it!!!! all the drives ive had have been just frickin teases. oh and the clutch on my DD 86 celica wentout so i NEED to finish my alltrac asap:/

12-18-2010, 04:39 PM
oh! and also, when i put the key in the ignition and turn it to on, the battery light is supposed to light up but it doesnt. and ive swapped the bulb into another spot that lights up and it lit up there, so its not a burnt out bulb. and also the battery light never came on when the car was low on juice or before it dies on me (all like 3times it died when i was driving) so that goes back to my theory of a missing link...hopefully it has to deal with that 2 prong plug that i posted a pic of.

12-18-2010, 06:32 PM
You mentioned checking fuses, I assume that includes the 100amp fusible link for the alternator (blue square thing with a viewing window in the top of it). When the car is running does the indicated voltage at the battery change at all depending on what you have turned on (headlights, radio etc.)? What condition are the wire bundles going to the alternator? Not just the three wires to the alt plug and the thick one to the b+ post, but all those other guys. Who did the wiring on the swap and which harness(es) was used? I'm not a wiring expert but recently had to deal with several charging and alternator issues on my jdm (1st gen) swapped 165.

12-18-2010, 06:44 PM
the 100 amp kept blowing everytime i hooked up the battery. i couldnt figure out why but then i figured it out. i have the 2white wires that go to b+ grounding to the body :P i fixed that and replaced the 100amp fuse.

what i meant by pulling fuses was im going to see if i get a signal from that wire i posted a pic of. if i get a signal, then ill start pulling fuses. each time checking the wire for a signal. once i findout which fuse cut the signal to that wire, ill know what its for.

the wiring was done by an auto X team. they converted a 165 harness to work on the 185. i bought the auto x car from them with intentions of making it a DD. well the body was more work than it was worth. so i pulled the engine and put it in another 165 body. in the auto x car, the key ignition worked. and so did the alternator. in the new 165, theres this wierd security system in it. it requires a chip to be inserted before starting the car.well the car still starts without the chip being inserted so im assuming the system doesnt work.

i was just about to go start pulling fuses before my phone vibrated with an email regarding a reply to this thread. ill post which fuse cuts off power to that wire (if theres power to begin with going thru that wire)

basically:everything worked in the auto x car before i pulled the motor.

12-18-2010, 07:02 PM
well i did the fuse pulling. before any fuses were pulled, both prongs inside the plug read 12.44volts. i pulled the 60amp fuse and after that both prongs read .02volts. and it flickered between .03 and .02volts. and this was all with the car off and just the battery hooked up.

12-19-2010, 04:53 AM
I had this happen to a 5th gen i had a while back that i suspect had wiring problems. You should have key on power at one of the wires at the alternator. I dont remember which one, but if you dont thats your problem. That was my problem just ran a new wire to key on power and i was good to go.

12-19-2010, 06:26 AM
Where exactly did you run the new wire? My dad told told me to run new wires but I'm not sure exactly where to start them. Would I go straight from one fuse to the correct wire on the plug for the voltage regulator?

Or do I need to run it to the key before the plug? Because I know some wires go thru the ignition switgch before the alternator.

12-19-2010, 08:58 AM
just throwin this in. i went to bestbuuy today to get the old security sytem removed. the guy knew me and fixed the starter problem for free.(old "security" system still installed) now my key ignition works. he cut out the part of the alarm that cut off the starter. since the signals going to that had been cut, it kept the starter automatically in cut off mode. so now my key ignition works. i wonder if the battery light comes on now when i turn the key to the on position...hmmm...

but after that the alternator still didnt work.

12-20-2010, 04:29 AM
just look up wire diagram for the alternator. One wire is for the battery light, one is key on power, and one is 100 amp fuse.

12-20-2010, 04:31 AM
The diagram like the one in my initial post? :)

12-20-2010, 04:56 AM
haha yes the one i didnt look at. With the car running unplug the plug and touch battery power to the prong that #3 should be. You should here the alternator make a noise and you should be charging.

12-21-2010, 04:01 PM
Did you get it figured out?

12-21-2010, 04:09 PM
Yeah! Giving prong number 3 a constant 12volt did the trick. I can't believe I've been doing almost 2weeks of fiddling and it was solved by 1minute of wiring...thank you so much!!

12-23-2010, 07:53 AM
Just so you know, #3 IG should be a switched 12v not constant 12v.

12-23-2010, 09:51 AM
gotcha. its currently spliced to myfan wire which only turns on when the keys to the on position.


also, any idea what this large plug is? id assume its for all the A/C and heater sstuff since thats all currently out, but its fuse is grouped with the alternator fuses...if you pull out the 60ampfuse, this wire no longer gets a 12volt signal from the battery.

07-26-2011, 10:03 AM
gotcha. its currently spliced to myfan wire which only turns on when the keys to the on position.


also, any idea what this large plug is? id assume its for all the A/C and heater sstuff since thats all currently out, but its fuse is grouped with the alternator fuses...if you pull out the 60ampfuse, this wire no longer gets a 12volt signal from the battery.

Sorry for reviving an old thread, but did you ever figure out what those plugs were?