NEED HELP PLEASE. 17 volts on alt. overcharging

[steveo3318]

Ok I just got my 67 in and blew a cheap battery out of it. Figured it was just cheapo previous owner installed. Well I put a dura last agm gel battery in and fired her up. Since my volt gauge stayed dead center all times I figured I would put my volt meter on the batter. And wow it would put out up to 17.8 volts as I increased rpms. I know this is not correct. Can anyone give me some guidance on what to check and what color wires to check. Maybe a fuse is blown on the gauge. How do I check this out.

[imjeff]

Separate voltage regulator? Can you post some pics? These trucks end up with at least one of everything electrical that GM has ever made.

[steveo3318]

Yes it has a seperate voltage regulator. I will take some pics this afternoon when I get in. Tganks

[TBONE1964]

Your voltage regulator is stuck. Replace it immediately to prevent any damage to other circuits. Any thing un-fused as well as bulbs will most likely fail if this is not repaired. I would expect that you would blow some fuses also.

Good call on the meter check. You should never have over 14.5 for any reason.

[steveo3318]

Yeah already had a headlight blow and a running light. I may just get a gm one wire as I hate trying to trace down regulator problems and such. May get a regulator first though. Is there a way to check tge voltage gauge???

[Wrenchbender Ret]

Make sure the regulator is grounded. A reg. that is not grounded will go to infinity. There is a small hole in the side of the base. A metal screw goes in it to fasten a ground wire. Its best to run this wire to the ground on the alt. The reg. is mounted on rubber mounts.

[steveo3318]

Can anyone tell me the pin outs on the regulator and what they should be getting and receiving voltage wise?

[67 chevelle]

I had the same issue , replaced the regulator and fixed it

[CST10]

Just wondering what the lower limit is before having charging issues?

[Hawghauler]

Originally Posted by Wrenchbender Ret

Make sure the regulator is grounded. A reg. that is not grounded will go to infinity. There is a small hole in the side of the base. A metal screw goes in it to fasten a ground wire. Its best to run this wire to the ground on the alt. The reg. is mounted on rubber mounts.

I agree, I just had my regulator die completely, with a new battery and alt. I replaced my regulator, I was in a hurry because I had a long drive home. I didn't ground it and it did exactly what you describe. I think my Flukes meter read 17.5 volts when I shut it off. So I put the condenser back on and used the same hole to run a ground wire to the rad support. Cheap fix = ground it. Mine came with a little condenser, I think to suppress radio noise.

[steveo3318]

Well I bought a new regulator and got home to find mine was not original and a bit of a hack job. So I simply pulled the alt and went back to autozone and grabbed a single wire gm alt and left everything unhooked but the positive wire. Will not charge more than 14.6 volts now. Thanks for all the advice but over the years of trying to trace down a regulator issue or wiring I have found a gm one wire has served me well over the years. Ps. With my rewards card the alt was 36 bucks and has a free lifetime replacement. My trucks not a cherry so not being complete original does not worry me. The regulator was 29. Bucks lol

Next issue. Can anyone tell me how the charge gauge works and the pin outs on it. I am going to test it and see if I can't get it working.

[imjeff]

I wasn't really happy with the one wire on my 72 so I went back to the 2 wire.

[steveo3318]

What kind of problems did she show u????

[imjeff]

Just didn't seem to keep the battery as charged. I may have just needed a bigger wire. When I talked to my alternator guy about my theory that the one wire wasn't doing it he looked at me like I was the last kid in class to get it and said "we don't do a lot of those". Since they have fixed all my alternators (usually costs about $10 to $15) and have replaced some that were years out of warranty, I tend to listen to the man. He's a gold mine. Not too many places you can walk in to, drop a broken alternator on the counter, grunt, and walk out ten minutes later with a rebuilt with your pulley installed or your repaired alt.

[cwilkie]

Go to a one wire alternator. Just buy that jumper kit and a one wire alternator. I did and I have not had any problems in three years.

[steveo3318]

I put a one wire on it. What jumper kit are you talking about

[ray_mcavoy]

Originally Posted by steveo3318

Next issue. Can anyone tell me how the charge gauge works and the pin outs on it. I am going to test it and see if I can't get it working.

VetteVet gives a good description of the ammeter (aka "battery gauge") system in post #3 of this thread --> http://67-72chevytrucks.com/vboard/s...d.php?t=556345

Two important things to note are: (1) There are two 4 amp inline fuses that protect the ammeter and it's wiring from overloads and short circuits. Check to make sure both of those fuses are good. And (2) the output of the alternator (no matter what type it is) needs to be connected to the factory junction point in the wiring. If the alternator output is routed directly to the + battery terminal, it bypasses the ammeter's "shunt" wire and it will no longer be able to register the charging current.

If those things are all okay, check the connections on pins #1 & #12 of the instrument cluster connector (black w/white stripe & black wires). Also check the cluster's printed circuit for burned/damaged traces and check the connection points where it's attached to the back of the meter.

[steveo3318]

It's still charging through the factory harness. I will check the fuses. Thanks for the help

[steveo3318]

Any idea where these two fuses should be located??????

[steveo3318]

Ok just found one behind passenger side headlight not hooked to anything. Has an eyelet connector on it. What's it suppose to hook too

[steveo3318]

IT LIVES!!!!!!! thanks for all the help. Found both fuses were blown and the one at the battery was disconnected. Hooked it up. New fuses and instead of being dead center if floats a little bit above center and increases a little as rpms increase. Extremely happy. Thank y'all so much.

[ray_mcavoy]

Originally Posted by steveo3318

Ok just found one behind passenger side headlight not hooked to anything. Has an eyelet connector on it. What's it suppose to hook too

The ring terminal on the passenger side fuse holder should connect to the "BATT+" junction block that's on the inner edge of the fender near the battery.

The other fuse should be on the driver side ... somewhere near the original voltage regulator location on the radiator support.

EDIT ... looks like I was a little late typing that up I see you've already found it and got it working !!

[VetteVet]

Originally Posted by steveo3318

Ok just found one behind passenger side headlight not hooked to anything. Has an eyelet connector on it. What's it suppose to hook too

If you looked at the link that Ray posted, you would notice the diagram which shows the wire in question. It connects to the terminal bolt on the right fender with the fusible link from the battery positive terminal.

The other wire is connected to the joint with the alternator output wire and the shunt wire from the battery and the red sensing wire in the bottom center of the diagram.

This is the diagram.



This is a condensed version. It shows the alternator and regulator wiring as it is in the factory version.



The destination of the two wires is in the console cluster plug at pins 1 and 12 that plugs into the instrument cluster. These are both positive wires and do not have to be wired through the key switch because there is no current draw on the circuit.



If you expect the battery gauge to work with a one wire alternator or with the three wire you must run the output wire on the alternator to the junction shown in the diagram where the stock wire is routed. If you wire it directly to the battery terminal like the one-wire directions say, then the battery gauge will not be able to measure a voltage difference between the alternator and the battery. It must be wired on one end of the shunt and the battery must be wired on the other end. Just like the first diagram shows.

The battery gauge has nothing to do with whether the alternator charges or not so don't get confused by that.

So if the gauge is good, the fuses are good, and the wiring is correct the gauge should work like the factory designed it to work.