Electrical Issue 1972 C10

[Bryon.Dillon]

Hello Again,
Well I got my truck to run, but now I am having some sort of electrical issue...

When we originally got my truck to run, we had jumper cables connected to my dads truck and it starts up just fine. We disconnected the jumper cables and the truck still ran, and I let it run for a bit to charge the battery up. My dad left and I turned it off about 15 minutes later, I tried to turn the key on and nothing, no click no lights, nothing. I tried to turn the headlights on and acessories, nothing. So I cleaned the battery terminals, cleaned the grounds, checked to make sure I was getting power to the distribution block, everything fine. I'm really stumped on this one, I mean my battery could be pretty dead, but i would still be able to see the headlights come on really dim right? The thing that doesnt make sense to me is that the thing will start up and run rine if it's jumped, but as soon as you turn it off, it's like there is no battery in the thing at all. I've got the battery hooked up to a charger and i'm going to charge it over night and see what happens in the morning.

[domeier]

I think you'll see that it didn't take a charge. Sometimes they go completely dead like that. Your battery cables are working, or it wouldn't have started with the jump, and your alternator and wiring are good, as it continued to run once the jump was removed.

You need to get yourself a multimeter. They answer questions faster than a magic 8 ball.

[SS Tim]

Originally Posted by domeier

You need to get yourself a multimeter. They answer questions faster than a magic 8 ball.

Insert the word "good" in that sentence. Cheap meter or leads will give you nothing but grief. Besides you can use it around the house too.

[white 67]

I had a battery go dead like that. I started the truck drove it in to the garage turned it off and tryed to start it and had nothing. It was do dead that it would not power the warning buzzer for the keys being in it, and it would not jump start with the battery connected.

[Hubscrub]

Originally Posted by white 67

I had a battery go dead like that. I started the truck drove it in to the garage turned it off and tryed to start it and had nothing. It was do dead that it would not power the warning buzzer for the keys being in it, and it would not jump start with the battery connected.

i did to i pulled into a car wash, washed car, dead, had to push it out of the stall and go get a new one

[cdowns]

i'd take the battery out and have it checked at an autoparts store then charge it up overnight on a trickel charger

[domeier]

Originally Posted by SS Tim

Insert the word "good" in that sentence. Cheap meter or leads will give you nothing but grief. Besides you can use it around the house too.

That's true, I should have said "good." I've had the same Fluke 77 since 1988. It's been dropped I don't know how many times, and used in the rain and the heat and snow and ice. I even dropped it in a bucket of vacuum pump oil somewhere in East Jesus China, and it still works great.

[leddzepp]

You need a new battery. I had the same thing happen to me at a gas station. For some reason they will short out and then they are dead, won't take a charge.

[Bryon.Dillon]

Ok, just went out and tried it, batter took a charge, the lights come on now but nothing happens when i turn the key. The thing that has me boggled on this is that when it's hooked up to my dads truck via jumper cables, it starts right up. Obviously the battery is supplying juice, or the headlights wouldnt come on and be bright. Even if there wasnt enough juice to start the engine, you'd think it would at least try just a little bit or something after getting charged all night.

[dmack91]

If you want to check quick, just pull the battery from another vehicle and substitute it for yours. If everything works, then it is your battery. If still nothing, you have other gremlins. Probably your battery though.

[Bryon.Dillon]

It was the battery, starting great now. Thank you again!

[Longhorn Man]

Now you need to make sure it is charging properly.
Posted via Mobile Device

[domeier]

Originally Posted by Longhorn Man

Now you need to make sure it is charging properly.
Posted via Mobile Device

Start it up, and put the jumper cables on your tongue. If your tongue explodes, it's charging good.

Or, you could use a multimeter. A good one!

[Bryon.Dillon]

Originally Posted by domeier

Start it up, and put the jumper cables on your tongue. If your tongue explodes, it's charging good.

Or, you could use a multimeter. A good one!

ROFL!

So what voltage should be acceptable for charging? 14+?

[Rooster's 67]

max of 14.5 like to see it around 13.5, 13.6,, 14.5 is a little high and can shorten the lifespan of batteries. Anything below 12.8 is not charging properly. poor connections and corrosion can cause high charging voltage if the voltage regulator is not sensing the real voltage of the system. Gonna need a "GOOD" voltmeter.

[Coley]

Good to hear your battery was the issue.
To make sure you are charging, put a voltmeter across the battery terminals when the truck is running...you should see better than 12 volts...and when you rev the engine it should rise slightly (13+ volts).
Then pull your lights on and do the same checks...it (the volt reading) should always rise with some throttle.
As well, a very simple check to see if the alternator is working in any vehicle is to slightly touch something metal (not stainless!!) to the back of the alternator (firewall side). It should produce a magnetic pull on the metal to the alternator. If it doesn't...check the plug into the alternator, if its old (and loose) it can appear to be connected but not putting the charge through.
Good luck, keep us posted!!
Coley

[Daze57]

Start it up, and put the jumper cables on your tongue. If your tongue explodes, it's charging good.


now thats what i'm talkin; bout !!!!!!!!!!!!!!!!

[Bryon.Dillon]

well it started fine for about a week, then yesterday i went out there and it was dead. I was like uhhhh? so i went and had the alternator tested and its fine. Replaced the voltage regulator and it seems to be working again now, will know in a few days

[VetteVet]

If you don't get an indication of discharging from the charging light or the ammeter depending on the dash cluster you have, then I would suspect that you have a small drain on the battery that causes it to go dead over a day or so. I would pull the negative battery cable off and tap it against the battery terminal while watching for a small spark that would indicate a draw on the battery. Do this with the engine off and if you have one you could use a test light instead or a multimeter.

[Bryon.Dillon]

So it cleared up a little and I was able to test for a voltage draw from the battery as suggested, and it did spark when i checked the negative battery cable. The first thing I did was disconnect the plug going to the alternator with a blue and white wire and there was no more voltage draw at the battery. What does this mean?

[Bryon.Dillon]

I'm assuming that both of these wires go to the voltage regulator

[Coley]

Yes, both of those wires go to the Regulator.
When you plug that connection in do you notice a 'load' on the motor? If not, you should...as the alternator, when charging, loads the motor down a bit.
Do you have an aftermarket radio in the truck? If so, often the guy who installs it (unknowingly?) wires it 'hot' to a fuseblock connection rather than to an ignition 'on' connection to keep the clock and station memory alive.
If you have an aftermarket radio, completely disconnect it and try the negative terminal test again.
Good Luck.
Coley

[Bryon.Dillon]

I actually didnt try disconnecting it and reconnecting it while the motor was running. I will try that and post the results. Actually this truck has no radio in it at all.

[VetteVet]

The alternator in your picture appears to be the internal regulator style SI series. The external regulated alternator plug in was on the back of the alternator. Some one has done the conversion without removing the external regulator. Both of the wires come from the external regulator and they are supposed to bypass and eliminate it.

Check the alternator and see if it has a 1 and 2 on the case by the terminals. The external alternator had an F and an R next to the terminals. This diagram shows how to bypass the external regulator and wire the internal regulated alternator. Check out your wiring and the alternator and see if the regulator is still wired up. If it isnt then check to be sure the white wire is connected to the brown wire by the regulator and see if the blue wire is connected to the red wire at the regulator. Then check the two wires at the alternator and make sure the white wire is connected to the no 1 terminal and the blue wire is connected to the no 2 terminal. The blue wire should be hot all the time and the white wire should be hot only when the key is on.



This is the external regulated alternator and below it is the internally regulated alternator showing the 1 and 2 terminals.

[Bryon.Dillon]

Some information about internally regulated alternators and externally. I'm pretty sure this should be an externally regulated alternator. Mine has the 1/2 and R labels on the back. The plug on my alternator is the || style not the -- style. Are you sure this is internally regulated? Is there any way to test it?

http://67-72chevytrucks.com/vboard/s...d.php?t=396437