Strange Power Loss - diagnosis help, please

Driving home from work in the light snow today, I lost all electrical power.

It's a 3 mile (20min) ride. First my radio went out. Following that my gauges all died, then interior lights, wipers, and turn signals all went out (headlights were barely lit).

The motor chugged once or twice in traffic, so I rev'd it (5-spd) and that kept it from stalling, but it mostly kept its idle. The radio even came back for a second on once I got 'er wound up.

Once I parked, it stalled after a few minutes. Only my jumper pack brought it back. It read about 10.5V on a crappy multimeter I borrowed while I got it running again.

95 4.0 D35 NP231, 1.5yo redtop, don't know what else is pertinent. It's my DD.

I'm not a Jeep doctor by any means, but I'm thinking alternator, starter, or maybe a bad ground (from searching "voltage drop")... but why would it go all-of-a-sudden like this?

Open to any thought. Cheers.

Start by freshening connections and load testing your battery. I know it's less than 2 years old but batteries can fail at any age. If battery checks out, you have to find out why it only read 10.5 volts so test your alternator or put that meter to use again across the battery connections at a high idle. Should be around 14 volts give or take.

Def check connections, and test your alt.

Clean your connections (take apart and polish and reattach) and test for close to 14V at battery while running. More often than not, it's the connections. The grounds make a difference too.

Tested battery. Replaced alternater. Perfecto! Who knew that could lead to voltage loss... :anon:

So why did you replace the alternator?

winterbeater said:

So why did you replace the alternator?

Click to expand...

Recharged battery and tested with multimeter - it read 13.5V-ish.

I was at my buddy's place because he has a fully functional garage, and his dad (a mechanic) checked some of the connections out (I don't know where all the grounds are), and recommended changing the alternator.

Since he had one sitting in his garage, (we have five X- W- and T-J's between us, so he stocks up on spare parts) that's what we did. It is working fine now; I've never seen my factory volt gauge this close to the 14V mark before.

So to answer your question more directly, I guess he recommended replacing it because the battery was OK and the ground connections looked fine as well. Maybe he had some other considerations leading to the decision that I didn't know about, but I dunno what they might have been.

Thanks for the responses; it feels good to have a source of advice when I need it most.

That makes sense. Some people have just replaced parts and cleaned up connections at the same time without diagnosing step by step. Thanks for the feedback.

x2 on the feedback, we are all here to learn.

:eyes: