MagnumD69

Can some folks post up their voltages taken at the battery posts? I want to compare to help diagnose my persistent battery warning light issue. No codes thrown.

Engine running Full lights & aux lights. 15.2v
Running idle no lights on. 15.15v
Engine and lights Off. 13.3v,
Battery Charger attached but unplugged. 13.0v and falling over time
Charger on. 14.44v constant with engine off.

See anything unusual? I am wondering if that 15v is high and the computer fried my last alternator and battery which were both replaced last month.

ronjenx

I believe 15.2 volts is too high.

With my engine running, the voltage at the battery is around 14.2 volts, max.

The rest of your readings look normal.

genesbro

Your batt light is on because the alt is putting out too much voltage. The batt light monitors the alt not the batt. and it will fry your batt at that kind of voltage.
Should be around 13.8-14.00 at full charge.

Lorrel

Yea your battery reading of 15.2 does seem a bit high.
The static charge of my battery is about 12.6VDC.
With the vehicle running, my reading is about 14.6 VDC. (at idle)
When I turn on all electrical components including the heater on high in defrost mode so the condensor is also running the voltage drops to about 13.8. (at idle)
At about 2500 RPM the voltage increases to about 14.6.

MagnumD69

Thanks for the responses. I think I we are narrowing down to the root cause of my woes.

The battery light came on again this morning on the way to work. I stopped and tested the voltage at the terminals. 14.45v

Check the attached picture.

The cable indicated was wicked hot. Too hot to touch and some of the insulation looks like it has melted!

What could be causing this? The PCM? I have scheduled an appointment at the dealer to get the 18-036-06 TSB performed along with some recall work. What should I tell the service tech? I don't want my flame red to flame up!

Octo

I saw another thread recently that the alternator in our Jeeps has very little electronics in it. The regulator is actually in the PCM, so if you have already replaced one battery and alternator you might not have fixed your problem if the regulator is bad.

Vernnz

Tell the service to check the alternator regulator. Also tell him/her about your high voltage readings. Also let them know that whatever is causing the high voltage also damaged that wire. You want that wire replaced.

The wire is hot because it is carrying more current than it is supposed to. Any time you feel a warm or hot wire something is wrong.

JK-Ford

This was posted from "rutdigger" on an earlier post.

lest we forget
https://www.jk-forum.com/forums/show...ltage-question

rutdigger

Yes..15.2 is to high...it's overcharging..definetly get that thing in to be serviced. If a wire that size is getting that hot, some serious amps are going thru it. be VERY VERY careful when driving that thing and go straight to the dealer! Maybe that is the cause of some of these jeep fires that we are reading about.

MagnumD69

It's at the dealer. Wating to hear the prognosis.
I have thought the same thing about the fires after burning my hand on that wire. I wonder if it happens more often than people realize? Maybe I have just been lucky?