I bought a 79 c10 got a wierd electrical problem

[1982blazer]

I bought a decent 79 c10 long bed just for fun. Earlier today i was trying to see why one of the head lights only works intermitently. I had my ratchet on the positive battery terminal, and my shirt was realy sweaty and when i touched my side to the front core suppurt i could feel electricity flow thruogh my arm it must have a short somewhere. I got the head light to work now just by pluging and unpluging the pig tail to it. but the truck is still shocking me. i also think the head light that was working intermitently might be slightly dimmer than the other headlight i will be able to tell once the sun goes down. I know it is a vague problem and hard to diagnose over the internet but any tips on how to fix it would be great or just figure out whats going on. touch the postive battery terminal and then touch even the headlight bezel or core support with my other hand and i get shocked.

 

[TerryD]

Kinda how it works....

 

[Doc Feel Good]

if one is dimmer.. check your grounds... that is common...

 

[1982blazer]

thanks i will check the grounds, Maybe the shocking thing is as simple as my body was completing a circiut but i wouldnt normaly be able to feel it , but since i was drenched i could.

 

[Fordum]

thanks i will check the grounds, Maybe the shocking thing is as simple as my body was completing a circiut but i wouldnt normaly be able to feel it , but since i was drenched i could.

That is exactly what it was.

You are conductive normally, but you have real high skin resistance, and 12 volts is not high enough for it to 'push' enough current for you to feel.

Get coated with a salty conductive coating, that wets your skin and lowers the resistance, and you get a shock.

This is why you get a reading when you grab hold of the leads of an Ohmmeter. Even though you don't feel it, a current is flowing from one hand across your body to the other.

Being an electronics tech, I have done that I'm sure literally thousands of times.
Never gave it a thought until a few years ago where I read that a Marine electronics student got killed by an Ohmmeter.

I did not believe it at the time, but it was a reputable magazine, and what they said happened, seems to make sense.

He was playing around with a Simpson, trying to get the lowest reading he could by wetting his fingers and squeezing hard.

Finally, being a Marine, he figured he would bypass the skin altogether.
He either sharpened the probes, or they were already sharp.
He jabbed one into each thumb.

Blood is way more conductive than skin. And the amount of current across the heart muscle necessary to stop or disrupt the beat is amazingly small.

They found him dead.

Have fun working on the truck......

 

[diesel4me]

Hmmm...suicide by multi-meter!....

I've heard of a few guys being killed by an HEI ignition ,that had heart troubles..

I never though 12V could give you a shock,till my friend tried scraping the cigar lighter socket with his fingernail in hopes of making a better connection so he could get the lighter to work and light his ciggarette--he yelped in pain and I saw SMOKE come off his finger!!--gave him a nice burn!...I scoffed and said "Thats impossible,12V cant shock you...he was ticked off,and said "oh YEAH??--and grabbeed MY hand and shoved my finger in the socket,and proved me WRONG,when my finger got just as burnt as his did!....

Another friend almost lost his finger when his high school class ring got pinched between a wrench and the fender as he was removing the battery cable..turned orange in a matter of seconds and his finger was nearly burned in haolf--took 2 years for it to grow back and was never "normal" again...that incident showed my why its important to take the negative off FIRST and connect it LAST!..

 

[1982blazer]

Well the headlights are working now, and my c10 passed the state saftey inspection today. The truck is 100% street legal noweven tho its a 2wd im still having a lot of fun with it.

 

[nad]

That is exactly what it was.

You are conductive normally, but you have real high skin resistance, and 12 volts is not high enough for it to 'push' enough current for you to feel.

Get coated with a salty conductive coating, that wets your skin and lowers the resistance, and you get a shock.

This is why you get a reading when you grab hold of the leads of an Ohmmeter. Even though you don't feel it, a current is flowing from one hand across your body to the other.

Being an electronics tech, I have done that I'm sure literally thousands of times.
Never gave it a thought until a few years ago where I read that a Marine electronics student got killed by an Ohmmeter.

I did not believe it at the time, but it was a reputable magazine, and what they said happened, seems to make sense.

He was playing around with a Simpson, trying to get the lowest reading he could by wetting his fingers and squeezing hard.

Finally, being a Marine, he figured he would bypass the skin altogether.
He either sharpened the probes, or they were already sharp.
He jabbed one into each thumb.

Blood is way more conductive than skin. And the amount of current across the heart muscle necessary to stop or disrupt the beat is amazingly small.

They found him dead.

Have fun working on the truck......

I thought an ohmmeter just reads ohms, how could it produce voltage? Maybe I'm missing something here... Anyway, that's a crazy story.

 

[Fordum]

I thought an ohmmeter just reads ohms, how could it produce voltage? Maybe I'm missing something here... Anyway, that's a crazy story.

An ohmmeter has a battery inside that puts a known voltage through the leads. That voltage flows through the unknown resistance and the meter reads the current, which gives you the resistance using Ohm's law.

Voltage/Current=Resistance.

For the electronics guys out there, I know thats not exactly correct.
Its not a known voltage, they use a bridge circuit, but its too late/early to try to explain a bridge circuit.

 

[Doc Feel Good]

As a guy who works around elec. ever day. Some things to remember:

Its not the voltage (pressure) that kills you, its the amps...Only 10 milli amperes (0.0001 amps) through the heart is enough to kill a human.

Now voltage (pressure) is what gets past your natural resistance,ie skin. So if you are sweating, you just lowered your resistance.

Never wear rings, necklaces, or conductive items while working. I personally remove my rings and watch before wrenching.

Remember to have safety glasses on, yeah I know they fog and are a pita, but you only have one set of eyes.

just mah .02 worth