This is weird

[matches]

Went to start the truck today and just a click. While checking the battery, I found that the negative post has power! My test light shows no power on the positive post and power on the negative post. Ground to the body, light on the negative post, shows power. Battery is 5 years old and I have done nothing to the truck prior to this happening. Any ideas?

 

[NIsaacs]

The ground is bad, the test light is being your ground.



Nick

 

[matches]

I don't understand. When I put the light on the negative post of the battery and the ground for the light on the body, the ligh bulb comes on. Why does the negative side of the battery have power?

 

[NIsaacs]

It's kind of hard for me to explain, but the negative side has power during power draw. You must have something on that is drawing power, maybe under hood light or dome is on or some other source. The flow from the negative battery post to ground will light the bulb if your main ground is bad.



Sorry, maybe one of the engineering types will explain better.



Nick

 

[matches]

Ok, I appreciate the help. I will check the negative battery cable and get back to you. I have never experienced this before so it really had me scratching my head. That's why I come to the TDR, to find smarter people then me.

 

[matches]

So it turns out that the negative cable is bad. I tested it with an ohm meter and get all kinds of different resistance numbers. I will replace the cable and post again after. Thanks again.

 

[matches]

Ok, no new cable yet, but I used jumper cables to ground the battery, and problem fixed! Thanks Nick!

 

[HHhuntitall]

Think of it as the flow of water..... the electron flow is coming from the positive side of the battery, out the wire to wherever it's needed, dome light, radio, ignition. Then it flows from there out the ground wire back to the body, which is metal and conducts electricity. You hook your ground lead onto the body, and when you touch the probe to the battery post, you complete the circuit, making the light come one, although the electron flow is reversed from normal, yet the filament in the bulb glows from the current passing through it. The post on the battery probably has some corrosion, which is common, and not allowing the current to jump across the gap and form a circuit. Cleaning it should fix the problem.

 

[NIsaacs]

You are welcome and read HHhuntitall's explanation. He did a better job then I did



Nick

 

[matches]

That's a great explanation. I had a new cable made ($44. 00) and I am back up and running. Thanks again!

 

[ENafziger]

Glad you found the problem!

If you need some GREAT quality cables, this guy has some good stuff: Heavy Duty, Aftermarket, Custom Battery Cables for your Car, Truck or RV

--Eric