snflupigus

how do i diagnose what to fix... i know the alt is good, wires to starter etc are good. fusable links good. how does the alternator know it needs to charge more than 12v. ive goet 12v on the back of the alt and 12 on the large wire in the plug and 12 on the small sensor wire when the key is on. probem is, none of em jump to 14 when the car is running. the car is just running off the battery...

just in case you dont know... 92 305 tbi... thanks..

Low C1500

As far as I know, the alternator gets a 12volt signal in (the small wire thats connected to the plug, that plugs into the casing). If there is power there when running then the problem is the alternater itself. The 14volt output is regulated by the alternator internally.

dimented24x7

iTrader: (2)

i would guess that the voltage regulator bit the dust. The voltage regualtor uses a series of internal diodes as a feedback mechanism to basically dissipate any excessive electrical energy as heat to keep the voltage at a constant 14.4 instead of, say 18-20 volts so your battery doesnt get fried. If its been overheated or excesivly loaded, itll burn out and the alternator will stop charging. It could also be a bad winding in the armature as well. Id just go get another alternator if you dont want any hassle. I think the regulator can be changed but if its an origional alternator you might as well replace it since it will probably have a worn commutator, dud brushes, and worn bearings.

snflupigus

guess i didnt mention.... this was an overnight thing. no alt whine or anything, but i assumed it was the alternator when i noticed no charge and the car was about to die from driving only on the battery..

so. i put a new alternator in. its not charging either. this is my problem. the new alternator was tested at the parts store after i installed it and took it back off because it wasnt charging, it tested fine, so they say... they also tested my old one then, it was shot...

any ideas now.

bigREd car

<has the same problem going on right now.. all wires to starter are fine.. but for the life of me i cant figure out wear the fusible links are..

new alternater also... semi new battery.. the car bogs. if i punch it it feels like a spark plug isnt connected(not getting enough volts to my ignition system)...

last resort do a search maybe someone has explained fusible links for dummies.. and exhange my battery..
Shawn

Low C1500

Test the signal wire when running.

bigREd car

is there another fusible link i dont know about other then at the starter? i changed the 3 wires down there.. i dont want to go back maybe one of them is fried.. i just bought some wire that said fusible links might be my first mistake...
is there another fusible link near the battery?
Shawn

dimented24x7

iTrader: (2)

Looking at the schematics...

Disconnect the output wire form the rear of the alternator and the 3 wire connector. Both the large output wire that leads to the terminal block near the batteryt as well as the red wire in the three wire connector that traces back to the terminal on the starter should be hot at all times. If not, one of the fuseable links is bad.

The tan/white wire in the connector, which also supplys power to the fan relay, should be hot when the key is turned to the on position. If this one is not hot, check the fuse for the fan in the fusebox under the dash.

If any of these wires dont have 12 volts when the key is turned to the on position, the regulator, which is voltage sensing, will not activate and pass current to the battery when the alternator is running.

edit: theres a black wire as well that apears to be grounded when the voltage is high/low but its listed as not used on the wiring diagram.

bigREd car

dude i blew mine.. i smelled them.. i am not using fuseable links anymore.. sorry snuf for stealing you thread..

i have searched for alternative and i am going to use a fuse 60 A fuse
Shawn

chevy doesnt even use fuseable links anymore why should i?

dimented24x7

iTrader: (2)

which one is it? All of them? Id use a fuse that is rated for at least around 15% greater then the continuous rated output of the alternator if its the positive lead from the alternator.

snflupigus

so for my problem....

i have power to the rear wire, 12v constant to the red wire on the plug and 12v on the tan when key is on.

none fluctuate to anything but 12 when the car is running..... all fusable links are good as far as i know.

do i need to try a new alt, if that doesnt work, what the heck could be my problem...

dimented24x7

iTrader: (2)

hmmm... im at a loss for this one. Like you said in your first post, the alternator has a path for power at all the neccesary wires. From the sound of it, your battery is still good and accepting a charge. The only thing i can think of, other then another bad alternator, which seems unlikely, is poor grounding. Even though this is unlikely as well, its probably worth checking the resistance between the negative battery terminal and the alternator housing. Obviously if its not zero, or very near zero, you have a bad ground. There is also the possibility that your battery is bad and not accepting a charge, somehow causing the alternator not to supply power but i had a battery grenade on me (bad starter caused a short) and my alternator continued to power the car untill i got home. Like i said in my post to bigREd car, there is a black wire there as well but it doesnt appear to be part of the charging system. it looks like its just a path for a ground to turn on a warning light when the voltage is high or low.

snflupigus

the battery is good. ive charged it twice now from dead and it still tests good and holds a charge fine... its pretty new.

im just going to let one of the techs go through it down at my parents dealership... if he test everything ok. im going to return the reman delco to the parts store and buy an aftermarket oversized i think. I do have a PPI 2400 pulling power often. i usually replace the alt every year and a half. but i dont get voltage drop when the sub hits so i thought i was ok. maybe it killed the alt and wiring... I'll let you all know. its a stumper i guess.

25THRSS

Just a quick question. Do all L03's have the same amp alternator? How about all third gen's in general?

dimented24x7

iTrader: (2)

Wow... Even with my 135 some odd dB system in my olds i never blew alternators. Maybe its time to get a good aftermarket alternator and some caps to help out with the peak current draw.

jlbolin

snflupigus im having the same thing happening to my 91 firebird tried fusible links that wasnt it, tried 6 different alt's that wasnt it either, tried another diode on the sence wire to signal a voltage drop , no luck there either,dont know what it is either.if you find out please let me know.

Low C1500

I leaning towards a grounding problem, could be the alternator casing to the block, or the block to the frame ground.

snflupigus

problem was checked over by a GM tech. he tested everywire related.... checked out ok. alt voltage was 12 on back from the battery, 12 on the red wire on the plug constant. and 12 on the signal wire. It never jumped to 14 however when the alt was spinning. The alternator tested FINE on an alt bench.

answer is. When an alternator is placed under a load it reacts differently than on an alternator bench. It was putting out 12v but very very low amps on the car. when spinning it should have jumped to 13.5-14v on the signal wire (maybe both plug wires i guess) and on the back of the battery.

Swapped to a new alt, everything was fine. the problem WAS a bad alternator, or voltage regulator within it i guess. Never trust a test bench for an alternator, and if you have oriely auto parts stores in your area, dont buy electrical items from them.

hope this helps others in the future.

bigREd car

well i finished using a multi meter today.. testing everything i could.. with car off i got 11.5 volts at the battery which would be from the battery getting drained... turned car on.. still 11.5..
tested both red wires at the alt. one gave out a steady 11.5 and the other jumped up and down.. could my problem be the same? it seems as though my alt isnt giving out the proper voltage.. and it isnt charging my battery at all...

Shawn

oh yeah tested voltage inside the car 11.5 as well??? autozone better just let me exchange the pos,even if there test comes out fine...

snflupigus

explain to them that the alternator may test fine on the bench, but it has NO load on it. Its not a real life test. Tell them you checked it all out, and it is not your car, its their alternator and you want you money back or a new alternator.

I nearly had to go into explaining Ohms law to the tool at the parts store before he believed i knew what i was talking about. Even after I told him a gm tech checked it out and put a brand new delco on and it worked. After that, "I was like, well, maybe you you're right buddy, it must be my car."

Whats their worst case scenerio, they give you a new alt and you take their "working" one back? and you still have the problem... Bet you 10 bucks you wont have a problem. Sounds like the voltage regulator inside the alt is bad.

bigREd car

when i got my new alt i figured i should get a new plug for it as well.. The plug that hooks up at the top.. my old plug had only 2 wires coming out.. a red wire and a black wire. the new one had 3 wires a red wire black wire and a brown wire.. i hooked it back up red to red black to black and left brown out.. brown IS NOT CONNECTED

could this be my problem?? I have done a search and it shows it is needed for the alt to start to charge??
thanks
Shawn