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This is getting frustrating, turns out I do have a wiring issue, my alternator keeps getting hot and shorting itself out for some reason however im not sure why because on the plug i have the red wire to the alt and then the main battery red wire to the alt and then the white wire to the brown wire for inside the car so im sure it's wired correctly at least but my alternator wont stop shorting out do I just go to a junkyard to find a positive battery cable harness which is the starter, alt and fuel pump fuse or what should I do, any help is appreciated.
What is the voltage across the batt terminals with the engine both not running and running? When it's running, what's the voltage between the Big Red Terminal and the case?
Currently what ive decided to do which did end up working so far is I created a better ground from the motor to the body using a old negative terminal wire that I replaced which s\made the car run smoother for some reason so I am assuming was a bad ground maybe. anyway with the key on accessory I got roughly 11volts and then when the car was running would jump to about 13 and a half so im assuming the issue got fixed because the big red terminal on the alternator itself ofc will get hot because its pumping juice but it didnt get to the point where it was smoking like my last alternator did.
Currently what ive decided to do which did end up working so far is I created a better ground from the motor to the body using a old negative terminal wire that I replaced which s\made the car run smoother for some reason so I am assuming was a bad ground maybe. anyway with the key on accessory I got roughly 11volts and then when the car was running would jump to about 13 and a half so im assuming the issue got fixed because the big red terminal on the alternator itself ofc will get hot because its pumping juice but it didnt get to the point where it was smoking like my last alternator did.
U need to ground the firewall to the engine & the engine to chassis. U should have the battery to the fender connection.
My '85 T/A has a QJ - car made to export to Canada. With the car idling at 900 rpm cold, the battery charges at 14.5 volts at the terminals.
I can take a picture of the wiring at the alternator & posy it if u would like.
NO NO NO NO NO NO NO NO NO. Do NOT do it this way. It is WRONG.
Batt cable should go to THE BLOCK, or as close to it as possible. That's because the SINGLE LARGEST CURRENT DRAW is the starter motor; and the biggest cable needs to go where the biggest current flows. The factory usually used whatever bracket was closest to the batt, which thus resulted in the shortest possible cable. The cable is the highest resistance part of that system when done right.
There should be other ground connections at various appropriate places to accommodate various smaller currents. Obviously the alt case is grounded to the block (or arbitrarily close, electrically, to it), so you don't have to worry about that. There should be AT LEAST one connection from the engine or neg batt terminal to the chassis; the factory used 2, with one from the neg cable at the batt end to the fender-ish area, and one from the back of the engine (pass side head) to the firewall. The one at the fender is great for returning headlight current in particular, while the one at the firewall handles loads inside the car. A car with a really hungry fuel pump, or other such high-current loads, might need additional grounds near them; these should then be connected to the block.
Above all, DO NOT try to use the chassis as the "central" neg batt cable connection point!!! That's a near certain recipe for wires that burn up when you try to start the car, a starter that turns real slow and struggles to turn the motor over esp when hot, and all the rest of those common symptoms you always hear about.
Let's lay off of "assume" for the moment and jump directly to FACTS. What are the voltages in your system (a) across the batt terminals with the engine NOT running and the key off; (b) across the batt terminals with the engine running; and (c) across the alt from the Big Red Post to the case; and (d) from the alt case to the neg batt terminal with the engine running?
WRONG WRONG WRONG!! there a separate wire from the negative cable from the battery to the fender liner!
This cable cable can also be sacrificial if a short occurs. Had that happen on a 1970 Chevelle. If that happens the battery will not charge properly.
There s/b a ground from the firewall to the block to the chassis from the block. Completes the grounds.
Last edited by 72buickgs; May 14, 2023 at 07:18 PM.
Sorry about that, the negative battery terminal was not changed what so ever sorry if there was confusion, ive reversed what I did, thought if maybe if the engine to body ground was better maybe it would help with any ground issues but I see the mistake now my bad. car when off the terminals ready about 12 and then when car is running goes to about 14.5 volts. not sure what the issue was with my alternator, I have yet to check the volts to the alt case. so far the car didnt have any issues with the alternator and for some reason seemed to run smoother from the alt bracket to body "ground" mess ive created but I took it off as it seems like it was wrong.
there a separate wire from the negative cable from the battery to the fender liner
Yes indeed there is, as I said.
the factory used 2, with one from the neg cable at the batt end to the fender-ish area
That wire is not intended to be "sacrificial". By design, it is not ordinarily in the alt charging circuit either, UNLESS the hilljack shadetree SCREW-UP of hooking the main batt cable to the chassis and then the engine to the chassis, is made. That mistake forces ALL current between the engine and the batt - the starter load, the charging current, and the various minor loads under the hood like ignition - to go through that itty bitty wire, if one of those incorrect connections goes bad. All that current will surely burn up that little hair of wire. That's EXACTLY why hooking the main neg batt cable to the chassis is WRONG.
There s/b a ground from the firewall to the block
Yes indeed, as I said:
and one from the back of the engine (pass side head) to the firewall
The BIG MISTAKE, the MOST WRONG POSSIBLE THING YOU CAN DO, is hooking the main neg batt cable to the chassis. Under no circumstances should it go there. It goes to the BLOCK, or as close as possible, like to a bracket at the pass side front of the motor. That way, the starting and charging currents - the highest sustained currents in the car's electrical system - both go through the main neg batt cable ONLY, with no other connections, no other pieces of wire, etc. in the path. Just look at a FACTORY NEW car. ANY car, ANY brand, ANY age. There's A REASON they're ALL done that way. Many reasons actually.
Correct wiring is: main neg batt cable to the block (or close to it, like a bracket physically near the batt); a smaller (#12 or #10 is fine) from either the block or the batt terminal, to the fender-ish area, for loads like headlights and such; and a much larger (#6 or #4 is typical) from the engine to the firewall, to carry all the various interior loads like stereo, power accessories, rear lights, etc., for which the factory used a piece of uninsulated braid that was maybe #6.
GM wired the main neg batt cable to THE BLOCK, or to something as physically and electrically close to it as possible. For example, the carbed V8 Camaros had it going to the little "pistol" looking bracket at the bottom of the alt. Various late 60s and early 70s Chevys had it going to the upper alt bracket. The TA at that time would have been different, being a Firebird; the batt was on the driver's side, so the cable would have gone to some part bolted to THE BLOCK, or maybe even the block itself, on that side, which is opposite the alt. I don't know offhand exactly what part it was but I'm QUITE SURE it went from the batt to the block.
MAIN NEG BATT CABLE we're talking about here. It's big, thick, black; maybe 4 gauge; about 3/8" diameter; has a giant thick ring terminal on the end farther from the batt. It has a star washer between the ring terminal and the object it's bolted to, to bite through the paint and corrosion, and make the best practical connection to the solid metal object. It goes from the BATT to the BLOCK (or bracket bolted it the block). It DOES NOT stop at the chassis, firewall, frame, or ANYTHING ELSE. Batt to block. It is arranged this way so that it routes the starter current, the single highest current in a car's electrical system, returning from the starter motor case to the batt by way of the path with the lowest resistance, fewest connections, and shortest wire of the largest gauge available. And, since the alt case is solidly connected to the block, it also serves THAT high current, which is the 2nd highest sustained (not transient) current in the car's wiring, with the same low resistance, minimum connections, and shortest & fattest possible wire.
Then, there is a little pigtail coming off of the batt terminal end of the cable, that went to the fender. It was #12, maybe as large as #10.
LITTLE PIGTAIL we're talking about now. NOT the main neg batt cable.
Then, there was a braid cable about 8" long, that went from the rear of the pass side head to the firewall. It was probably about #6 equivalent.
CONNECTION BETWEEN ENGINE AND FIREWALL is what we're covering now.
I've had probably 40 cars that were all wired EXACTLY this way. For example, my 74 454 Caprice has the neg batt cable going to the top alt bracket. All of the 69 Chevelles I've ever had (at least half a dozen... at one time, my little bro and I even had a SS396 coupe 4-speed, SS396 coupe auto, SS396 convertible auto, and SS396 El Camino auto all at the same time) were wired EXACTLY this way.
My 04 Avalanche has its main neg batt cable going from the batt terminal to either the block itself or the PS pump bracket (driver's side batt). It then has a braid from the head to the firewall, and various other much smaller jumper wires from the block or accessory brackets to the fender, electric fans, and whatnot. I'd expect a Firebird to be similar to this.
I've never seen ANY GM car, or any car from any other mfr for that matter, wired any differently from this. This is the universal CORRECT way to run the batt cables & grounds.
I never said that was wrong I said apparently my extra ground from the motor to the radiator support is apparently wrong since everyone says so even though the car ran smoother with that extra cable. Never said the ribbon from the firewall to block was wrong was just stating that its original wiring so could not be grounding right is all I was getting at.
I understand just fine what you are saying, yes my MAIN NEG cable from battery is bolted to the block because I replaced it already to the exact same spot it was bolted to and the little pigtail that is also apart of that cable on mine went to the radiator support right behind the driver side headlight closes to the battery, The block to firewall ribbon as its called is in fact there but because it is original wiring and was outside in the elements for over a decade no one is sure if its even fully there or grounding like it should or snapped and ect, all I was trying to get at is I was just seeing how the car would react if a stronger ground was added to the car in case of any bad grounding in the said area around the engine bay or any other electricals, with this way how I did it the car ran smoother and all issues ive had with wiring went away that I knew of. Thats legit all I was trying to say and accomplish here, didn't need to get defensive and straight up tell me im just wrong and that I should assume all my factory grounds are perfectly fine.
You can add "extra" grounds just about anywhere you like. They don't hurt anything. Above all, if an added one makes a noticeable difference, then it's ... good. If it WORKS good, it IS good. After all, the various contact points where pieces of the car come together and touch and make electrical connections, tend to corrode and otherwise age poorly. They certainly aren't going to improve with age.
That's a whole other matter besides running the main neg batt cable to the "frame", chassis, firewall, or ANYWHERE ELSE besides the BLOCK.
Note in vorteciroc's drawing, he has a #2 doing just exactly that; along with the lesser "batt to chassis ground" connection that's an analog of the factory's little pigtail that goes to the fender-ish area in our cars; and his "block to chassis ground" is similarly equivalent to the braid from the head to the firewall. Main difference in his diagram is, it's for the batt mounted in the interior, rather than under the hood. Otherwise, it's EXACTLY what the factories all typically do, as the "backbone" of the ground system.
Seems like a misunderstanding at first, sorry for any confusion that started the said argument. Yes the diagram I already know how all cars are with battery grounding and such. The ground I added to my car did make a noticable difference in how it ran and responded so I would say that it is alright, yes my alternator still is working good and no problems have occured since the last issue.
Don't worry, you're not the one I have been speaking to. The 72 Buick guy seems to want to talk people into hooking their main batt cable to some part of the chassis instead of to the block. A whole other matter from yours.
Like I said, if adding a ground made the car work better, then it's better. It can't possibly hurt anything. I don't think it's ever possible too have "too much" grounding, up to the point that it starts making the car heavier. Which, you'd be surprised (or maybe not...) how much the total wiring of a car weighs. It's SEVERAL percent of the total vehicle weight. Which is why the factories all do their best to minimize that, while maximizing function; IOW, EFFICIENCY.
Yea no problem, however remember the whole thing where I seemed to not have anymore alternator problems...well that WAS the case. you know how if you turn the air on volts could drop a very tiny bit and maybe when in gear, yea so currently if i turn my air on my volts drop and then when I go into gear my volts drop and if I have the air on while in gear they drop really far down like that's not good down, id like to get an opinion if its just drawing that much amps or if my alternator is in fact going bad which would suck ngl cuz this is my 4th one tracing down some type of short the alternator was getting, has new plug and main power wire is perfectly good I know for a fact its working, the old brown wire which becomes white for some reason when you buy these new plugs for the alt case for those cars is fine (the one from the plug that goes to the firewall and such) maybe just maybe not saying this is it but I did run the car before that new ground I added that did make a difference and maybe there was in fact a bad ground somewhere because after the extra ground the car did make a noticable difference in running as I stated before, anyway i'm getting off track, volts in accessory read about 12 as they should (did not think to get a picture) but I have 2 videos one where I turn the air on and the volts drop a bit and another where I go into reverse and then drive then to neutral to finally park where the volts drop then theres a picture of the volt gauge in the car when I have both the air on and i'm in gear so i'm wondering if maybe you could help me troubleshoot as in if its normal even though i'm pretty sure it just should not do that and if there is a possibility that it was a bad ground when I ran the car before the added ground I created shorting out the alt from improper grounding maybe? i'm not great at electricals just understand some basics so any help would be great thanks for being patient with this one. (excuse the rattling in the going into gear video, it does that cuz i kinda have the interior apart and things are just lose)
Problem with that more likely is, you have an alt that simply doesn't have enough ooomph to power all that stuff at once, to the degree of comfort you've come to consider as normal. Back in the day we didn't know any better, that's just the way it was. Nowadays with cars coming with alts that put out TWICE what ours did OR MORE, we've come to expect more.
I mean that could be the case however I came to find out that if I have the air on (and in attempt to see if higher rpms gives more "oompf") and I rev it then there is squealing which I could only assume is the alternator dying from load. It is a FI 305 so the alt should be a 108 amp which is the one I got so even then would the volt drop be normal if it was a perfect working alternator? Signs are pointing to possibly a bad ground shorting out the alternator before I added my extra stronger ground but just asking for input because does seem to make sense in my head.
"Bad grounds" don't "short out" the alternator. A "short" (short for "short circuit") is an unintended connection between 2 points that aren't supposed to be connected. Not likely to be an issue here. In any case, adding grounds wouldn't fix such a thing, if it existed. Might help in other ways, but not with a "short".
Try tightening the belt first and see if that gets rid of the sqweeeling.
Damn sorry I just jumped to the conclusion of a bad alternator because of how many i've gone through, I did go and tighten the belt and the squealing did in fact go away and now the car starts with the volts not struggling to gain anymore. my bad and thanks again.
