Electrical Problems?

[k5baby]

My 72 k5 blazer is not reading 14 volts when cranked. I replaced the alternator, new battery, new wiring harness and I can't still get it to charge. Eventually after driving it with the headlights on the battery will die and I have to recharge with battery charger. When you take the positive off the battery it will also die. It has to be a wire where do I start? I've checked the grounds. The guy at the parts house wanted to no why I had a voltage regulator on the core support and one built in the alternator, a total of two. I'm kinda curious myself. Thanks in advance for any suggestions.
I also posted in the Garage.
My backup lights don't work either. Is there a back up lamp switch somewhere for a 3 spd I can check?

 

[jaros44]

Back up switch

It's located on the floorboard by the brake pedal. Did you check your grounding strape between the body and the frame?

 

[Jimm]

alternator or generator ?

My 71 has a generator with a external regulator mounted behind the front head light. Jim

 

[jaros44]

Prince of Darkness

Actually, I may have misled you. I have an automatic that used to be a 3 spd. and mine is on the base of the steering column. Your right about the 2 voltage regs. I never thought about it but there does seem to be an extra one on rad. support!!!! I'm afraid this isn't much help but I'll keep thinking about it. Later J.

 

[jaros44]

2 volt. regs.

Would the wire lugs be the same for a gen. or a alt. I believe gens. have 1 wire system as my alt. does so maybe someone switched mine over to a 1 wire system alt. Let me check the factory wire diagrams and see if I can come with anything!!! Later J.

 

[k5baby]

I've looked at the factory wire diagrams and it shows the way I have it. I think its a broken wire somewhere or bad connection. This friggin sucks I have it finally put back together and I can't even figure out some damn electrical problem. How hard can it be it was built in 1972!
As far as the backup switch the diagram only shows where a four speed switch is located.
I also have new bulbs in my front turn signals (1157) they come on with my headlights but will not flash, the back flashes fast. Do you think it may be a flasher?

 

[Jimm]

On the older model trucks the method I use for finding shorts is to disconnect the battery. Then hook up a volt ohm meter to the battery leads and set it to ohms. If there is a short causing the problem start unplugging connections including fuses and watch the meter as you do each connection for the circuit to go open. Jim

 

[jaros44]

Grounds

Check all grounds!!! Make sure it's shiny metal and even put some die electric grease on them, even the sockets. When I restored british cars it was almost always grounds!!! Just my .02. Did you look on the steering column? Later J.

 

[k5baby]

Setting the meter to ohms - You said keep the voltmeter leads on the positive and negative of the battery while i'm disoneecting wires/fuses till it comes open? What should the meter read when the circuit becomes open?
Should I have fuses in the rubber links on each side of the headlights?

 

[jaros44]

Electrical Prob.

You only have fuses at the main fuse block under the dash drivers side, unless someone added one to power up an added electrical device, such as a radio or lights. What Jimm is refering as open is the circuit is not complete. You want all circuits to be complete as in closed or a complete loop. Your reading should be as close to zero as possible, hence no resistance. Put your meter on ohms and touch your red and black leads together and you'll see what I mean. In that configuration you have a completed circuit. By the way do you have any current pics. of your truck??? Later J.

 

[k5baby]

That's what I thought. I worked a little bit on it today. Checked all wires for any breaks and found none. The alternator still was only putting out 12v while running. So I went back up to the auto parts place and had it checked. Turns out the alternator is bad That's the second one in 3 days how odd is that. First one was an AC Delco second is an off brand, hope the third one works!
Been so busy with these little things I haven't had a chance to snap any pics. I'll try to do that in the next couple days.

 

[jaros44]

Alt.

Dude, believe it or that happens a lot. I'm going to start checking them before I leave the store. Maybe that why I like to rebuild my own alt. I think the kit is about 14.00. I'm just glad you solved your problem, electrics can be a nightmare!!!! later J.

 

[ZZ4x4]

I bought a 1 wire alt for about $75 through Summit and ditched the regulator stuff. I will certainly do that again if I ever get the chance. All you need is the single red wire going to the battery and let the alt do the rest! Then get rid of all those useless wires.

 

[jaros44]

1 wire alt.

Nice pic of your truck, that is exactly like mine(72 GMC custom) whenit gets done. Could you post more pics it really did come nice!!!! I was wondering what size lift and tires??? It sits the way I want mine to. Anyway, do they have the higher amp alts. available? Sounds pretty easy as you say it and I would like to get rid of some of the clutter under the hood. My wife gave me an electric water pump and 2 pc timing chain cover for Christmas and I want to hang the alt. and AGR pump on March brackets so it should clean everything up with a one wire alt. Later J.
p.s. Did I tell you your truck looks GREAT!!!!

 

[Leper]

Look down around the battery base, where it is bolted on, for a loose wire. I fixed a guys truck by finding a wire that had broken off of the battery cable and fallen down, out of sight. I would imagine that you have the same problem. I wire is loose/off/corroded somewhere. And you are right, that age of a truck is really simple to diagnose.

 

[ZZ4x4]

I was wondering what size lift and tires??? It sits the way I want mine to. Anyway, do they have the higher amp alts.

Thanks. The lift is a 4 inch Tuff Country springs in front with an ORD shackle flip and zero rate offsets in back. There is also a 2" body lift for a total of about 6" lift. The tires are 36" TSLs. There are certainly higher amp single wire alts available. Magnum makes a 90A version and Powermaster has a 140A model I believe.
Jeff

 

[jaros44]

140amp

Thanks for the info. I was looking for 140amp so it looks like I can get it. My wires are in good shape, just a lot of them!!! With that one wire set up and no external voltage regulator, it should clean up nice. I just found a place to buy that non sticky electrical tape so I can rewrap what's there. I plan on march brackets and since I have an electric water pump all I have left to do is buy an AGR power steering pump. My motor mounts were trash so I bought a set of Prothane mounts. I can't believe you can't remove the front crossmember!!! Oh well I'll just clean up around it. I plan to run 2" body, and 4" susp. so it should sit like yours, but 35,s Thanks for the info. Later J.