Jeep Overcharging and Overheating need help!

DBats

New member
Hello everyone! (if this is a double post please delete, my internet hiccup'd as I posted this)

I'm chasing down a gremlin in a bad way and I need some advice on what to do.

Jeep is a 2012 JK 3.6 with 82K

Here's what happened: Was driving to work at highway speeds when my battery light illuminated and stayed on. Pulled over and used my flashpaq to scan the computer, pulled code P2504- Charging system output high. Figured my alternator was on it's way out, started the Jeep back up to make it into work and park it. Battery light did not come back on, jeep drove fine on the highway. As I got closer to work I hit traffic that brought me to a stop, after ilding in traffic for 5 minutes the battery light came back on followed shortly after by the temperature warning light. I looked at my temperature gauge and saw that it had pegged all the way over to hot. I immediately navigated out of traffic and shut the jeep off, I could hear the coolant boiling from inside the cab and sure enough there was coolant splashed all over the engine bay. Without wanting to do any more damage to the engine I had it towed back to my house.

First thing I did was to pull the battery and alternator out and have them tested, they tested fine at two different shops. I then set out to try and find something, anything that might be obviously wrong. I spun the water pump to see if it's seized, it spins freely, I pullled the serpentine belt to see if there was any idication of slipping or scuffing, the belt is a few months old and looks fine. I checked the tensioner, which is also fine. The thing I really don't know is if the overcharging issue and the overheating issue are related or two completely separate issues that just happened to pop off at the same time. I was looking to check the battery/engine grounds but I don't know where to look (if anyone has any pictures that'd be awesome).

Could these two problems be related? Could an overcharging issue fry or stop something like my radiator fan to stop working and cause the overheat? I'm open to any and all suggestions! Thanks!
 
If the belt was spinning I doubt they were related. If the alternator is actually overcharging next time it says that check it with a voltmeter to get the exact volts, it’s possible it’s a intermittently failing voltage regular/ rectifier. Unlikely but possible that it’s failing under high heat conditions. Also possible the excite /trigger wire is still getting power.
For the overheating start with basic stuff and work from there. Radiator clean, flush system, thermostat is a cheap part to throw at it.


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Did you check the other pulleys too like PS and AC ? Almost seems like the two symptoms may be related somehow.
 
Did you check the other pulleys too like PS and AC ? Almost seems like the two symptoms may be related somehow.

I did, everything spins freely like it should and I pulled the belt off to see if it was scuffed or excessively worn like if it had been run over a stuck pulley and like I said the belt still looks brand new as I replaced it about 3 months ago. I dont think it's any of my accessory pulleys. To me it definitely feels like both of these issues are related but I can't find anything that screams "HEY IM BROKEN" lol.
 
Does anyone else have any thoughts on what might be causing this? Or does anyone know where I can find the engine and battery main grounds in the 12+ JK's? Some people are saying on the frame, others say it's on the firewall or even on the body. Pictures would be super helpful if anyone has any laying around.

I've looked all around and there are a bunch of different topics covering overheating in the JK's but none that I've read so far where the temperature pegged and got hot enough for it to vomit coolant.

And thanks again for the replies so far.
 
Does anyone else have any thoughts on what might be causing this? Or does anyone know where I can find the engine and battery main grounds in the 12+ JK's? Some people are saying on the frame, others say it's on the firewall or even on the body. Pictures would be super helpful if anyone has any laying around.

I've looked all around and there are a bunch of different topics covering overheating in the JK's but none that I've read so far where the temperature pegged and got hot enough for it to vomit coolant.

And thanks again for the replies so far.

Although the two issue occurred simultaneously, I wouldn’t assume they are connected, at least for diagnosis and treatment.

Re the overheating, is your electric fan working? I was recently reading some threads about coolant temp sensors going bad and all the havoc that can cause. Among other things, it tells the fan to turn on and off. It’s a cheap part that’s easy to replace, so maybe check that.



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