Eric is performing this heater circuit test in this video at 56:40 on an S10 with a test light. Eric and South Main Auto is one of the best vehicle repair you tube channels.


George

 

That was a pretty good explanation. Thanks. One question though. Is there something I can buy, preferably cheap, that would make the check safe from a jolt? Or just anything safe to put in there.

 

It's 12V DC so you can't get shocked unless you put something in your mouth or in an open wound or your wet, especially with salt water but even that would just tingle like a battery to the tongue, if that's what you mean. When you start back probing, these come in handy, just make sure that you don't touch them together when they are in the socket:


Since your worried about getting shocked, here is the deal. You need more voltage to get a classic "shock" and risk stopping your heart. Our bodies are conductive but they are also a big resistor and low voltages are not enough to cause harm. The golden rule with higher voltages (house 110V and up) is never grab with both hands which can make a path across your heart and never grab with a fist because you may not be able to let go. If someone else is getting shocked don't grab them with your hands. If you want to check, brush with the back of your hand first. That's why you don't trip the circuit breaker when you get shocked in a house because the resistance of your body limits the current, but that lower current can stop your heart under the right conditions. That's why ground fault breakers were invented. They sense small differences in the current between hot and neutral wires which indicates a dangerous fault. I work on tube amplifiers and the 500V involved requires a lot of respect. We use chop sticks and one hand in our pockets when the amp is live. I have been bit a bunch of times with 110/220V. I don't recommend it and safety first but I am still typing. In my old age I do walk back and turn the breaker off like I should most of the time now.

Back on Blazers. Metal tools can produce major fireworks however, especially with unfused power. A wrench on battery + shorted to ground can produce major sparks and a lot of heat. I know someone who had a wrench in their hand at the battery positive post and created: Batt +> wrench> ring> frame. The resultant hundreds of amps through the rink vaporized it into pieces one of which fell almost completely through the top of the plastic battery case from the heat and they got a permanent tattoo on their ring finger. No shock to the heart just a s**t ton of heat and a big scare.

One last thing. Its an entirely different story when it comes to automotive testing when the circuits back to the ECM are involved because it is possible to burn out a circuit driver and ruin the ECM if your short the wrong pins so make sure that you know what you are doing, double check your wire colors and don't let the pins short together.


George

 

I thought I had replied. I had it all typed out and it was just sitting there. I don't think I'm really worried about getting shocked. It's really more about ruining the plug if I bridge the + and - like you said. It wouldn't be the third time. Usually smaller scale though. I've seen what you're talking about with the wrench but with a stable gun.

I think I have some probes from other wires that I can use to be safe If it comes down to it, I might just go have my dad show me how to do it.