Gremlins again

[Doug&Deb]

Let me start by saying that my electrical knowledge would fit in a thimble with room left over. I’m chasing a problem with my Coronet. I have a simple test probe. Wherever I touch it on the car it lights up. Is that telling me I have a problem or am i doing something wrong?  I obviously have a short or bad ground, I’m just not sure how to isolate it.

[pflaming]

Disconnect your  battery cable. If it doesn't spark when you reattach it, , you do not have a ground problem.  I'm not much more knowledgeable about electrical than you, but it seems to me if you have a ground problem, a fuse should blow or wires should be melting. JMHO 

[kencombs]

2 hours ago, Doug&Deb said:

Let me start by saying that my electrical knowledge would fit in a thimble with room left over. I’m chasing a problem with my Coronet. I have a simple test probe. Wherever I touch it on the car it lights up. Is that telling me I have a problem or am i doing something wrong?  I obviously have a short or bad ground, I’m just not sure how to isolate it.

a little more info is needed!

 

There are two ends/contacts to the probe.  Where are both of them touching when it lights?

[Bbdakota]

2 hours ago, Doug&Deb said:

Let me start by saying that my electrical knowledge would fit in a thimble with room left over. I’m chasing a problem with my Coronet. I have a simple test probe. Wherever I touch it on the car it lights up. Is that telling me I have a problem or am i doing something wrong?  I obviously have a short or bad ground, I’m just not sure how to isolate it.

When you touch it on the car and it lights up, you are completing a circuit for current to flow. What is the other end attached to? 

[joecoozie]

As stated before, one end of the light (typically the end that has the alligator clip) gets attached to a good ground. i.e. battery ground (which, if your car has the original 6 volt system would be the positive post on the battery) or any clean metal on the car. The other end of the light then gets "touched" to whatever you are trying to check for current flow.

For a quick test,connect the clip end to the grounded post of the battery (follow the battery cable and it should be connected to the engine block to verify that is the ground post) and then touch the other battery post with the probe end of the test light. It should light up.

If you have the test light clip end attached to the "hot" side of the battery then no matter where you touch the probe end to metal it will light up. All that is doing is completing the circuit for the battery.

[Doug&Deb]

The probe has a wire with an alligator clip to attach to ground. Touching the probe completes the circuit.

[Silverdome]

Assuming that positive is your ground. If you touch the cylinder head with the probe while the alligator clip is attached to the body of the car or the positive post on the battery the light should not come on.

[Doug&Deb]

I’m thinking I have a bad ground. Over the winter the engine was rebuilt ( twice, don’t ask). I’m going to check under the car to see what I can find. I’m also going to add a ground strap from the block to the firewall. If I throw enough money at it surely it’ll eventually be fixed. LOL!

[Doug&Deb]

Either the car temporarily fixed itself or i figured it out. There are 2 wires wrapped around the  e-brake cable that were making intermittent contact. It appears to be the brake light switch harness. My switch is near the rear axle. Not sure why or why these wires were left hanging but I hope I’m done with that problem. Thanks for all the suggestions.