[BigTB]

If I understand correctly you suspect your ground cable is bad and are wondering if you can try jumping it from another vehicle by connecting just the ground terminals of the batteries? If so, no that will not work. If I've misunderstood what you are asking, feel free to clarify.

Does the engine crank at all? If you are concerned your ground cable might be the issue, just connect the negative side of the jumper cable from the ground post of your battery to a clean spot of metal on your engine and see if that makes a difference. In that test you would basically be making the jumper cable your ground cable.

Have you tested the battery? What are the details of your issue (intermittent, all the time, no crank, crank but no start, etc., etc.). The more details, the better.

 

[BigTB]

Also. Jumped car drove ten mins to get the battery starter and alt tested. In about ten minutes needed jumped again to drive home. So im thinking the ground strap is preventing it

When you jump the vehicle, do you connect the jumper leads directly to your battery, or do you connect the negative clamp to the chassis/engine ground? If you connect directly to the battery terminals then it's not likely to be the ground cable.

Did you try connecting the negative jumper lead from your battery terminal to a clean ground on your engine/chassis to see if it will crank then? Do you have a multi-meter?

When you had the battery, alternator and starter tested, you say it had to be jumped again. How did they test all that if you couldn't even re-start the engine without jumping it?

It actually sounds quite a lot like a failed battery. I've seen batteries fail in lots of ways, so it's certainly not impossible for it to be bad even if it's not very old. But it could be a bad connection or bad cable as well. I would check to ensure both the ground and positive cables are tight at both ends.

 

[BigTB]

I have a multimeter. What exactly should i be testing and what should it show

I would set the meter to DC voltage and put the leads directly on the battery terminals to check battery voltage. With the the meter connected, note the battery voltage. It should be approximately 12.6V if fully charged. If it is much below 12V it is either dead (needs charged) or bad.

If the battery voltage is good, with the meter still connected, have someone attempt to crank the engine and see what the voltage does. If it barely drops but the engine doesn't crank, it could be an issue with one of the cables or connections. If it drops below 9 volts and the engine doesn't crank, the battery is bad.

If the battery voltage is good, and doesn't drop much while attempting to crank the engine, you can use the meter to test the cables. First, connect the meter's negative lead directly to the battery negative terminal and connect the positive lead of the meter to the engine block somewhere (clean, bare metal). With the meter still set to check DC voltage you should have zero volts. With the leads still connected this way attempt to crank the engine again and see what the meter shows for DC voltage. It should still be relatively low, under a volt. If you see 5-12V DC when attempting to start with the meter connected to the negative battery terminal and the engine block, then you have a bad ground.

You can test the positive cable in a similar way, but it is a little more difficult because you have to go between the positive battery terminal and the positive connection on the starter.

Post up if you have any questions about any of this.