Additional Ground Cable

Don S · Aug 6, 2025

I have a 2024 GMC Sierra Denali with the 6.2L engine. I tow this truck behind my motorhome. When towing a GM, you need to disconnect the battery as the last part of the procedure for Neutral Towing. As part of setting up my truck, I used a Roadmaster electric battery disconnect. It's an electric solenoid that allows me to disconnect the positive battery cable from inside the truck with a switch.

I did the install and on my truck, which has just a single negative battery cable that connects to the battery. Yesterday, I did the same install on a 2025 Yukon Denali with a 6.2L engine. While doing the install, I saw that the negative battery cable had a second OEM cable that was spliced near the bolt down on the negative cable and then ran to a battery stud that is mounted on the edge of the fender, a few inches from the center of the battery. My truck has that same stud, but no secondary cable mounted to it. So basically, another full size negative battery cable that runs from the negative terminal to the stud on the fender.

So.....my question.....is there something GM is not telling us or is there a problem they're trying to resolve. Why did they add the additional cable from the negative battery terminal to the stud on the fender????

Don S · Aug 9, 2025

I think I answered my own question. If you need to jump start your truck, your battery has a lid with a red sliding door. When you slide that door back, it exposes a metal tab, approximately 1" x 1" that you can connect a jumper cable to. It would be almost impossible to get a large jumper clamp around the deeply buried positive cable.

The same with the ground. The cable is somewhat buried with a 10mm nut holding the cable on. Looking at the GM Manual under jump starting, they show connecting to the positive tab under the red sliding lid and to a tall nut that looks like a battery lug on the fender (see photo below). Page 409 of the Owner's Manual

That lug is bolted into the fender/sheet metal. My guess, it may not provide a sufficient ground for jump starting. Consequently, they added an additional negative cable on the 2025's that goes from the negative battery post to the lug on the fender.

I bought a 10" #6 negative battery cable with 3/8" holes on both ends and ran it from the negative battery terminal to under that lug, making it the same as the 2025's. Now, jump starting will be direct to the battery.

gemarsh · Aug 9, 2025

Wonder if gm has realized that the braided cable from cab to the frame, behind the front right wheel well liner is junk and went with a better design?

Don S · Aug 9, 2025

I think a 1/4" lug bolted to a fender being used for a battery jump location is just a poor idea. The extra cable makes it a direct connection to the battery that is easy to access. I know you'll rarely if ever need to jump the truck, but I feel better with the new cable added.