GMC 2500 6.0L won't jumpstart other vehicles.

[Jared Smith]

I've been having an ongoing issue with my 2014 GMC Sierra 2500 6.0L gas not wanting to jumpstart other vehicles. It does not seem to have any output voltage. I've had to replace the battery several times due to an issue with a loose battery cable running the battery dead and wrecking it but I've rectified that issue and the truck starts perfectly fine and has no issues. However, whenever I go to jumpstart another vehicle or a piece of equipment, it appears to have intermittent output voltage. (And yes, the jumper cables are attached properly, I'm an old hand) When hooking them to the battery of the truck and then to the posts ony skidsteer, there are no sparks. Removing them from the truck and touching the clamps lightly to the posts also produce no sparks. However, occasionally there are sparks and good output and it will start up a cold skidsteer no problem. There does not appear to be any rhyme or reason. Is it a bad alternator?

 

[CamGTP]

The alternator would have nothing to do with it.

 

The battery voltage would be above 12 volts regardless of the alternator working and that is plenty of voltage to make the jumper cables spark when you touch them together.

 

All I could guess at would be being a bad set of jumper cables.