Factory ground on fire wall next to battery. Where does it go?
 

Today while driving I noticed a sulfur smell coming from under my hood. I pulled over and the battery was boiling over. At first I thought the alternator was over charging the battery but then I sow that the factory ground thats on the fire wall right next to the battery was missing. I couldn't find the factory ground anywhere in the engine bay. Does anyone know where that factory ground goes to? I have a 2014 Jeep Wrangler JkU btw.

Attachment 676347

Previous models 07-11 had a hood strap on that post. Hope this helps.

Did you trace the wires from the negative battery terminal? A wire would go from that to the side of the body by the fender, or some other ground point. If the battery were not grounded, the vehicle would not start.

Since you first suspected the alternator was overcharging the battery, did you check battery voltage with the engine running? It should be around 14.3 volts.
Battery gassing and/or boiling over is a sure sign of a bad battery, or alternator overcharging.

Yes I've done all of that. I traced the wires that are on the negative battery post but they all go into a wiring loom so its kind of hard to tell where they go exactly.

I tested this with a voltmeter and without a ground running from the battery to the firewall or from the engine block to the fire wall, the voltage reading is 17.69 (which is why my battery was boiling over.) As soon as I connect a ground, the voltage drops to 14.27.

As a temporary fix, I have put a ground strap from the engine block to the firewall. That brings the voltage to normal range, but now I have a check engine light. p0032, p0038, p0052, p0058 which are all HO2S heater control high circuit. I'am 99% sure that this has to do with that missing ground.

The lug in your first picture is used on my JK to ground the hood. That being missing should have no effect on your issue. See if your hood has a grounding strap somewhere else.

Disconnect both battery leads, negative first, and clean them and the posts. Reconnect, with the negative being connected last.
Disconnect and clean every lead you can find that is connected to the body. Reconnect, making sure each is tight.

Add a heavy wire from the battery negative to one of the alternator mount bolts.

See if that improves the charging voltage.


Since your battery has been overcharging, get it tested, including water level if the caps can be removed.

Are you sure thats where that ground goes? In the picture below you can see that it goes down into the engine bay. I looked all over the engine bay and still can't find it.

The old battery was trashed so I replaced it with a brand new Optima Red top. I took your advise and cleaned all the ground connections that I could find. I found 4 ground connection. 2 on each side by the fender. I also cleaned the ground connection of the PCM on the divers side next to the windshield washer fluid.

I added 2 8-guage wires running from the negative post of the battery to the alternator bolts and did not see a change in voltage. The voltage on the jeep still remains at 14.3 range.

Something really weird also happened when I was checking the voltage. The battery light was flashing continuously and the traction control light came up. I turned the Jeep off and turned it back on and the lights went away. I also notice that the Jeep takes a little bit longer to shut off now. Could that be because of the ground problem?

I looked at the engine codes again and I got a p0300 which is a random/multiple misfire. Could this cause the o2 sensors to obtain an inaccurate reading?


Attachment 676348

Ground wire
 

The wire goes to the side of the head I just replaced a head gasket and had this wire and one 8 mm bolt left over and remembered were it went after I put battery box back in. It’s very hard to get to if you have big hands but can be done.

how did you end up fixing this issue? I am currently experiencing the same exact issue!!!!!!

The wire you found.
 

So I was changing out my catalytic converters and saw the fat exact same wire that's connected to the heads, was cut. I put a new ground strap on it and the next morning my battery was dead any ideas?