What causes the "Generator" light to come on?

[67ChevyRedneck]

I'm starting to get a little peeved at my 67. It's been having some serious electrical problems. For a couple weeks it was randomly overcharging/undercharging. But it wasn't often. It got bad this week, so I changed the voltage regulator last night. Now it's undercharging between 10 and 11 volts and the "generator" light has finally come on (and is staying on.) I took the truck to advance to have the alternator tested. Everything checked out fine This is driving me nuts!

I've already checked and cleaned all of the grounds, the voltage regulator seems to be working properly, since the old one was allowing under and overcharging???

What makes the "generator" light come one? It never came on all the other times the truck was over and under charging. The first time it came on was right after I swapped the voltage regulator.

Is it just a generic light that reads a low battery or is it directly linked to the alternator to let you know that it's bad?

I'm really banging my head on the wall on this one fellas

[67ChevyRedneck]

Also, I took a complete underhood harness from a '72 truck that was in excellent shape (the wires all look good and aren't brittle and cracked.) The best part was that there wasn't a single cut or hacked wire! I unbolted it from the firewall and unplugged it from the fuse block.

I've been thinking about swapping the whole thing. Anyone know if the underhood harnesses were the same from 67-72? I thought I'd read somewhere the 67 fuse block was different, but I'm not sure.

[byrd]

I don't think the boxes are diff, just 67-8 mount horizontal and the 69-72 mounts vertical, or vise versa??
The light harness should be the same with the exception of the 72 having provisions for markers lights, but the engine harnesses I believe the engine harnesses are diff depending on manual or auto, v-8 or I6.

[byrd]

The blue wire off the reg signals the ammeter in the with gauges set up, but I would assume it would control the gen light in the dummy light set up.

[67ChevyRedneck]

^I'm confused as to why it didn't come on for weeks and now it is! I'm to the point to where I'm going to assume advance is wrong and my alternator is bad? It's only 30 some years old. If that's not it, I'm really stuck!

[dave2953]

The schematic I have for my 68 (dummy setup) shows the blue going to the generator light. Just a "b" by itself in the schematic does mean blue, right? Also, did you have the battery disconnected when you hooked up the regulator. I burned one up by doing this, or so I was told.

[67ChevyRedneck]

^Yes, I've accidentally "blown up" stuff before by forgetting to disconnect the battery, so yes, it was disconnected. So if the dummy light is coming from the regulator, I could, once again, have a bad regulator, which I doubt? or my alternator is bad?

I HATE electrical stuff.

We had tours for all the engineering fields when I was a freshmen at clemson, you had to go on at least four, I refused to go on the elcetrical one

[byrd]

Well if you are positive you don't have a bad/corroded connection then I would lean on the alt having issues. But why not just go ahead and upgrade to int reg now, sounds like you have the perfect reason, but I understand timing and $$ rule the world. I just upgraded mine to int reg and it was really simple and only cost about $60 and 2 hrs of my time. Just cut the wires loose at the reg and butt splice the brown and blue together and the red and white together. Then at the alt butt splice the white to the white on your factory style plug required(get with the alt) and the brown to the colored(red or blue seen both) wire on the fact plug. put the black ring lug under one of the case screws and the big red wire on the positive terminal, hook your battery back up and your done.I did this and the headlight relay at the same time and man what a HUGE differnence. MY headlights on my truck are now as bright as my headlights on my 98 Chrysler, and my truck's are the old sealed beam halogens to boot

[kbs71]

Does the light come on and stay on all the time?
Actually "b" stands for brown. If you look about a foot up twords the plug end of the harness from the 4 way splice on the drivers side and the same from the one lug connector over by the battery, you will see what looks like two small fuse holders. These house two I believe 2 amp short fuses. If one of them has blown, (which they like to do when you change external voltage regulators) it will cause the "GEN" light to come on and stay on.
Check them to see if they are blown. That may be the problem, especially if your alt is putting out 14 v and you have 14 v at the battery.

[67ChevyRedneck]

Thanks Byrd, yeah, I was hoping for a cheap fix. If you've noticed, my name has dropped to pink I got a little over my head jumping the gun on paying off my Silverado, but all will be good again when I get paid soon (I get paid monthly.) Just need to hold out.

I have a few questions for you. The faq is a little vague on this. My alt. is currently on the PS, but will need to go to the DS as I want to add a vintage air kit before the SC summers hit. I drove it during the summers 3 years ago and I looked like i just jumped into a pool after a 10 minute drive

ANYWAY, I need to put the alt. on the DS. My truck has a 77+ motor (I don't know the year, just a generic late 70's, 80's style block) with the long water pump.

I have a set of alternator brackets I got off of a 72 350 truck with the alt on the DS.

My question is, will the silverado alt. used in the faq work with what I have? Can it be shimmed to work? Do I need to go to a yard to get alt. brackets?

You can see why I haven't just jumped into the conversion yet, my truck is far from stock. I could put it all on a cc and pay it off next month, but the majority of the problem is I don't know what to buy for my set-up.

[byrd]

I cannot help you on that part, but mine is on the DS and I have a short WP.
BTW congrats on being without a car payment!! I went almost 4 yrs without
one until the wife said she HAD to have a new car

[67ChevyRedneck]

Originally Posted by kbs71

Does the light come on and stay on all the time?
Actually "b" stands for brown. If you look about a foot up twords the plug end of the harness from the 4 way splice on the drivers side and the same from the one lug connector over by the battery, you will see what looks like two small fuse holders. These house two I believe 2 amp short fuses. If one of them has blown, (which they like to do when you change external voltage regulators) it will cause the "GEN" light to come on and stay on.
Check them to see if they are blown. That may be the problem, especially if your alt is putting out 14 v and you have 14 v at the battery.

Man, you got my hopes up. I went out and checked... no fuses. The redneck dumbass who owned my truck cut and spliced the hell out of everything. Looks like the fuses had been removed in favor of spliced wires and electrical tape

[kbs71]

Don't know if this will help, but here's a copy of the wiring diagrams for your truck. The top of the page has red "x"'s where the link is but just go further down the page and they were reposted. I would try and help more but I've been up for 22 hrs and I'm not thinking stright. I need some sleep.
http://67-72chevytrucks.com/vboard/s...wiring+diagram

[byrd]

Originally Posted by 67ChevyRedneck

Man, you got my hopes up. I went out and checked... no fuses. The redneck dumbass who owned my truck cut and spliced the hell out of everything. Looks like the fuses had been removed in favor of spliced wires and electrical tape

idiot light dashes DON'T have the fuses only with gauges trucks do, you have to add that wire and the fuses when changing over from idiot to with gauges.