Voltage issues

[BACARDI_DWB]

ok, here is the story. started my truck up to drive to work one morning, drove perfectly into work, not one issue, i stopped at the gas station to fill up and then i get back in the truck and its dead, it clicked a few times but that was it. so i get a jump and park my truck since i was already late to work. i get another jump and head home, on the way home the truck ran like complete crap. it would not idle, hated low rpm's and always sounded like it was going to die.

 

so i first took the battery and had it tested, it was charged and tested good.

 

damn

 

I came home, the battery read 12.5v, started the truck and it read 12.4 volts, i pulled the negative cable and the truck dies immediately

 

damn

 

so then i took the alternator out and had it tested at 2 different places and it tested good both places

 

came home and started the truck and same scenario

 

damn

 

so i went and bought a brand new voltage regulator and installed it, did the same test, the battery read at 12.3 volts prior to being turned on, turn the truck on and its reading 12.2 volts. unhook the negative cable off the battery and it dies instantly

 

damn!!

 

do i take the voltage regulator out and get another one from autozone in case that one was fried, tested and started, same crap

 

damn

 

I have looked all over for shorts and i can't find any obvious ones

 

is there something i am missing? is there something i can do. it seems like the truck is only running off the battery and not running off the alternator when the truck is started?

 

Thanks for the help guys

[]2eDeYe]

Pull off the negative cable from the battery and run a test light between the cable and the - battery post. If the light comes on you have a short somewhere.

[datzenmike]

Clean the battery posts and make sure the regulator has a good ground to the body and the body has a good ground connection to the battery. I assume your charg light isn't on?

[BACARDI_DWB]

well you are right, i have a short somewhere, That is what i thought, but dreaded. i tested the neg battery cable to the neg post and i have voltage. its not only a little voltage. its a full 12.2volts. so that is a pretty big short somewhere. I have a bandaide fix for today so i can get to work (solar panel recharger)

 

Thanks guys, now to find the short. i have an idea that its most likely under the dash but we will see.

 

i am going to start pulling fuses first and see if that locates it.

 

Thanks again

[banzai510(hainz)]

dude YOu will read 12volt doing the VOLT test.Your just reading across the battery. (I know it doesnt look like it your measuring across the battery but you are)

 

 

Use a TEST LIGHT cause your using the CURRENT/voltage to turn on the light.

So remove the Neg cable from battery and put the Test light in the middle with key OFF. the light should be OFF. THis is a Norman condition you want to see.

 

to test this, put the lights or ignition ON then the test light will be ON.

 

If key is OFF and the TEST Light is ON. somthing is shorted. I alway remove the Altenator + wire and disconnect the volt reg. If OK put back wire and reg to normal and start popping fuses to see which circut.

 

you add a stereo? alarm?

 

If not I think its the alternator.

 

a unregulated alternator should ready over 15volts.

Disconnect the volt reg while running and see if alternator is causeing a overvolt. If yes then I say the the alternator is GOOD

[BACARDI_DWB]

ok i was thinking about that. it didn't make sense. I tested that last night when the store was closed. i don't have a test light, but i will get one when i get home.

 

Really i think my electrical system has been running like this without me knowing (only running on 12.5v). I have had no reason to test it since it has been running good, until now when the truck died. BUT i did give someone a jump the other day, that may have put my battery in a condition where it would not start. my truck runs good now, but its still only on 12.5 volts. so yeah something is wrong. it really would not surprize me if there are more than a few shorts. I am going home tonight and getting a test light, and then going to town on my electrical system.

 

Yes i still have the painless wiring kit sitting in my garage, so i am still dealing with the stock stuff. i have not installed it yet cause i have not had any time to take my truck down for a few days to install it, and allow for any issues that may come up. my daily driver is getting a new motor... grr no love from the auto-gods this month.

[datzenmike]

If you have 12 volts it should turn over. Clean the ground strap on the engine block and the positive cable on the starter.

[banzai510(hainz)]

What I did is get a Radio Shack diode cker. or use the ones that plug in the cig lighter

the cheezy one in my vedio Remember?. thats goes up to 15volts.

So I know right off the bat what my battery is doing and alwasy ck with the acessories OFF and give it a little gas and see what it reads.

 

I assume if everything is stock Datsun. Alternator and regulator?

if yes tell me.

 

ck the connections esp the battery connections and if old cables buy new ones,the 1 pc molded end type.

 

If your alternator is only pumping out 12.5 then when you put the lights, heater on the battery will eventually die. Like a totoal loss system.Loading down the system. Your meter should see this.

 

so get a good meter and ck this out(and test light). If you had a short your battery will die anyways when not running in a couple days or a day or so. If it starts OK I assume everything is good and I think you have a junk alternator or regulator.

PS the mechanical regs are shit in my opinion but a volt meter will catch this I hope. A Painless wire system is not going to fix this.

 

The only short right off the batt is you fucked with something or the rear lights are ON when you leave the truck. The stop fell out of the brake pedal up above to trigger the brake switch(happen to me)

 

PS, Your a datsun man you supposed to have another alternator ready to go in for trouble shooting!!!!!

[BACARDI_DWB]

the alternator is a 1972 240Z alternator, and the volt reg is AC delco for the Datsun 521 (stock)

 

Now for the painless system, i am planning on doing the Internally reg saturn alternator when i do that. i think i may be doing this sooner than i expected

 

things that are brand new:

alternator

volt regulator

cable from alternator to starter

positive cable

negative cable

positive battery connector

negative battery connector

 

oh yeah, I started the truck with the volt reg connected and disconnected and it still only read 12.3-12.5 volts

[banzai510(hainz)]

(oh yeah, I started the truck with the volt reg connected and disconnected and it still only read 12.3-12.5 volts)

 

 

I think this tells me the alternator is bad. and just reading the battery voltage.

 

Right off hand ,I SAY TRY ANOTHER ALTERNATOR. if you have no shorts(the Test Light ck)

 

 

anybody else have a opinion on his??????

 

Datsunmike?

Datsunaholic?

Mklotz?

 

 

A guy from Schucks told me once, that 3 out of 5 alternators are bad from the box!!!!

[BACARDI_DWB]

that is what i kept thinking. i have had the alternator tested at 2 different places and they both said it was good. but i guess i am going to test it myself, to verify.

 

I am also going to get another alternator from a friend and test it out. i love the fact that it only takes me 10min to tear out the alternator

[banzai510(hainz)]

yeah let US know,

Ever fix that rear seal in the axle?

 

 

But do the short test first before swapping out alternators.

[BACARDI_DWB]

bandaide fix on the seal (keep filling up the pumpkin :()

 

I know i have been procrastinating. I just have been extreemly busy, and i want to have a spare car ready incase i get too indepth into my rear end and can't drive to work on monday, so when i get my neon back then i am going to do it.

 

Also i am thinking about testing the Q45 LSD rear end when i pull the axle to fix. its the same spline count, we will see. 3.55 FD, not too bad. I have a open 4.11 in it right now.

[BACARDI_DWB]

OK so this is where i sit. i tested out and i don't have any shorts, :

took the negative battery cable off, put the test light between the cable and the terminal and got nothing. (and yes the light works)

 

i added a better ground between the alternator and the battery, cleaned up the main ground for the battery and i am still in the same spot.

 

i checked the voltage coming off the alternator and it reads 12.2 volts (same as the battery.

 

I am about to do the internally regulated saturn alternator, i am going to do it eventually but this might be pushing me over the edge to do it.

 

anyone else have any idea's???

[datzenmike]

.......I assume your charge light isn't on?

 

If there is no output from the Alt. the charge light should be on shouldn't it? Maybe it IS charging but the wire to the + terminal isn't good. Check the White/Red wire at the Alt, is it making good contact and tight??? There is an inline fusible link that the Alt. output has to go through to get to the + battery terminal. Look at the + terminal there should be a White wire going to a connector with a short length of Green??? fusible link wire with a connector to a Black wire. Unplug the Black wire and test if it has 14 volts on it when running. If cahrging 14 volts, it's not getting through the fusible link to the battery.

 

Long shot but cheaper than a new Alt.

[BACARDI_DWB]

I tested right off the alternator and it is not seeing more than 12.3v. i will test again. most of the wires are new and there is no inline fuses.

 

I am going to get a saturn alternator and do the one wire, wireup and see where i sit.

[joelyjoeljumpin]

A guy from Schucks told me once, that 3 out of 5 alternators are bad from the box!!!!

 

You can have them tested before you take it from the store , Maybe the ones they use are but I worked for Napa for three years and only had three out of the hundred of alternators sold actually bad from the start . NAE Reman line of alternators and starters are the way to go . I talked to one of the reps and he said you should never disconnect the negative while the vehicle is running its a good way to fry your electrical system .

[datzenmike]

I tested right off the alternator and it is not seeing more than 12.3v. i will test again. most of the wires are new and there is no inline fuses.

 

I am going to get a saturn alternator and do the one wire, wireup and see where i sit.

 

You should be reading 14-14.5 volts.