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So i swapped a 4 banger coupe with my 92 convertible GT (mainly cuz i wanted my built engine in the coupe). One day i will put the vert back to v8 but its not feasible right now. Anyway. now that i'm done with putting the 4 cylinder in the convertible. The battery light is on. Im not sure if its the dummy light or if there is a charging problem. My battery is in the trunk and is reading 12.1v even when i accelerate so i know its not the best. I had to splice the dummy light wire (i believe) to the harness to keep the 4 cylinder harness.

Anyone know where to start. I wouldn't mind upgrading the alternator but i'd rather not right now. See pics of the wire i had to splice right before the blue connector which i assume is the dummy light going to the dash.

Making things worst was i had prevoulsy tucked the wires in the fender. :/

Maybe someone can start with the wiring diagram for the 4 banger alternator?

TIA
 

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For whatever reason I can't see the pics. I know they are there but I can't see 'em.

12.1v is nowhere near enough. You should be seeing about 14v with the engine running.

You will want to trace your wiring closely and compare it to the wiring diagram. IIRC the 4 cyl and V8 cars have a different headlight harness, which also contains the wiring for the alternator; although I think it's the wire length that makes the biggest difference. I think the alternators are similar if not the same; at least in reference to how they mount. Amperage output may differ.

I put a full size 3G on my '93 4 cylinder car. 130A. Glad I did, BUT if I had to do it again, I'd put a small case 3G on as it fits a little better. The 3G is more efficient apparently because after the swap, it went from 34 mpg to 35.7 with no other changes. Either that or the large case 3G had something wrong with it which is entirely possible as it came from the JY.
 

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Discussion Starter #3
For whatever reason I can't see the pics. I know they are there but I can't see 'em.

12.1v is nowhere near enough. You should be seeing about 14v with the engine running.

You will want to trace your wiring closely and compare it to the wiring diagram. IIRC the 4 cyl and V8 cars have a different headlight harness, which also contains the wiring for the alternator; although I think it's the wire length that makes the biggest difference. I think the alternators are similar if not the same; at least in reference to how they mount. Amperage output may differ.

I put a full size 3G on my '93 4 cylinder car. 130A. Glad I did, BUT if I had to do it again, I'd put a small case 3G on as it fits a little better. The 3G is more efficient apparently because after the swap, it went from 34 mpg to 35.7 with no other changes. Either that or the large case 3G had something wrong with it which is entirely possible as it came from the JY.
Yeah i re looked it over and didn't see anything out of the norm with the wiring. I wish i knew why there is a 1000 wires coming out the alt on a 2.3 and only a few on the 5.0. I would assume to just re wire a new alternator in there and call it a day. I still can't figure out why the battery light is on unless it comes on when the battery is charging under a certain voltage but i don't see the computer being able to know that. I'm still looking for wiring diagram. :(
 

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For whatever reason I can't see the pics. I know they are there but I can't see 'em.

12.1v is nowhere near enough. You should be seeing about 14v with the engine running.

You will want to trace your wiring closely and compare it to the wiring diagram. IIRC the 4 cyl and V8 cars have a different headlight harness, which also contains the wiring for the alternator; although I think it's the wire length that makes the biggest difference. I think the alternators are similar if not the same; at least in reference to how they mount. Amperage output may differ.

I put a full size 3G on my '93 4 cylinder car. 130A. Glad I did, BUT if I had to do it again, I'd put a small case 3G on as it fits a little better. The 3G is more efficient apparently because after the swap, it went from 34 mpg to 35.7 with no other changes. Either that or the large case 3G had something wrong with it which is entirely possible as it came from the JY.

The alternator tested bad at two places so I might have found the problem. Do you know what vehicles have the small case 3g so i can grab one from the junkyard? and do you know if its exactly the same as a 3g upgrade in 5.0? if so i can find a write up somewhere
 

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Yeah i re looked it over and didn't see anything out of the norm with the wiring. I wish i knew why there is a 1000 wires coming out the alt on a 2.3 and only a few on the 5.0. I would assume to just re wire a new alternator in there and call it a day. I still can't figure out why the battery light is on unless it comes on when the battery is charging under a certain voltage but i don't see the computer being able to know that. I'm still looking for wiring diagram. :(

if your batt light is on, the alt is not charging

the alt is supplying the ground for the light circuit, the alt must see batt voltage in order to remove the ground when it is excited.

this is called fielding......you do not have it seeing batt voltage

supply the wiring diagram and i can show you
 

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Installed a 3g from a junkyard. Had to do quite a bit of grinding on the alt bracket but made it work. now at idle i'm at 14.3v :) and the battery light is off.
 

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so you tested the previous alt to be faulty?
 

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Installed a 3g from a junkyard. Had to do quite a bit of grinding on the alt bracket but made it work. now at idle i'm at 14.3v :) and the battery light is off.
You will like the 3G. THe small case 95A version fits a little better but the large 130A fits too with some modification to the bracket. They are easily rebuildable too, and cheap as long as it just needs a basic kit. A lot of times when I'm scouring the JY's, I'll pull the voltage regulator and have a look at the slip ring. If the slip ring's shot, throw the alternator back into the car. If it's useable, I'll grab the entire alternator and with the regulator missing from the back, they usually give me a slight discount. I just ordered a kit for mine which was $39 shipped, but I had to have a slip ring too for the other car, which adds a little $$$.

Something most folks don't do is rebuild alternators, starters, brake calipers, that sort of thing...since most parts stores have them readily available. But the kits to build them are dirt cheap and most aren't real hard to do at home with basic tools.
 

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so you tested the previous alt to be faulty?
Yeah. I never heard the 4 cylinder run when i bought my coupe and the seller didn't say anything. :/

You will like the 3G. THe small case 95A version fits a little better but the large 130A fits too with some modification to the bracket. They are easily rebuildable too, and cheap as long as it just needs a basic kit. A lot of times when I'm scouring the JY's, I'll pull the voltage regulator and have a look at the slip ring. If the slip ring's shot, throw the alternator back into the car. If it's useable, I'll grab the entire alternator and with the regulator missing from the back, they usually give me a slight discount. I just ordered a kit for mine which was $39 shipped, but I had to have a slip ring too for the other car, which adds a little $$$.

Something most folks don't do is rebuild alternators, starters, brake calipers, that sort of thing...since most parts stores have them readily available. But the kits to build them are dirt cheap and most aren't real hard to do at home with basic tools.
Yeah the alternator was 30 bucks at the junkyard so if it breaks i'll grab another one down the road for 30 bucks. A lot of them said remanufactured on them so i assume they aren't super old.
 
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