XJosh

battery level on dashboard shows up as 14 when in accessory mode before starting, starts fine every time, and drives fine with no electrical issues, however after driving for about 5 minutes the CHECK GAGUES light comes on and the battery level drops to 0.

is she just being moody again or should i be concerned?

the only things i can think of are wires, alternator, and ground... but i don't know where to start with any of those things.

i'm plagued with the usual electrical demons but i've never seen this happen before.

mcguyver_xj

if your vehicle dies after all that you need a new alternator

montanaman

Next time your gauge goes to zero, get out and tap the back of your alternator. If that brings your gauge back up, then you have some stuck or worn out brushes.

You can buy a remanufactured alternator, but a better alternative is to rebuild it yourself. It's not hard ... here are instructions:

http://www.jeepforum.com/forum/f11/r...1822aa-835511/

Replacing your brushes and bearings fixes 99.9% of all Denso alternator problems. It's a very quick and easy job. I'm a registered rebuilder with accounts at bulk suppliers. If you decide to rebuild it yourself, send me a PM, and I can get you the parts for cheap.

Good luck.

DFlintstone

Sounds like the gauge or it's wires. Everything works fine? Zero doesn't come up often without fire. Side note, the speed of the blinker is a crude volt meter.

tjwalker

Grounds can be the root cause of many electrical gremlins. Refreshing grounds is NEVER a bad idea, and the investment of your time in this procedure is always well worth it!

You can't tell much of anything by looking at ground connections!! You must remove, scrape, clean until shiny the cable/wire ends and whatever they bolt to. Be sure to remove all paint from any ground connections.

Start with the one on the back corner of the head, and where it attaches to the firewall, as it deteriorates over time and is an area that makes it susceptible to damage. Best to replace that woven cable with a #4 or #2 gauge cable. You can attach the one end to the intake manifold if you would like.

Next go over to the engine dipstick tube stud. Remove the nut and clean the wire ends and scrape the block until shiny at the stud. Reattach tightly.

If you are so inclined, add at least a #6 cable from the negative terminal of your battery to one of the bolts on your radiator support.

montanaman

'97+ XJ voltmeters are not just straight voltmeters. They are actually "charge meters", designed to drop to zero if the alternator stops producing when needed. The symptoms described in the original post are classic signs of a failing alternator, usually sticking brushes.

Having said that, I would also agree with checking all grounds, since that is always a good idea anyway.

XJosh ... please post back when you get the problem fixed, it will be helpful to future searchers.

Troth

Sounds like yoi have a short in your alternator. causes it to seize and amps drop to 0

XJosh

sorry didnt mean to leave yall hangin like that i've been busy with work and school.

the alternator died two days after posting this, and it was a quick, easy 180k maintenance job unbolt the stock alternator and plug in the new one. tested it in the shop and they said the internal regulator was bad and i didn't have the time to have it rebuilt so dropped $100 for the OEM one.

considered higher voltage alternators for offroad lights and possibly a winch in the future but didnt want to drop another $100 for 30 amps more. maybe i'll look into buying a ZJ alt from the JY and keeping this new one around in case that one dies too.

seems that the battery needle dropping to 0 is the tell-tale sign of a bad alternator. for anyone searching, swap that **** out or at least have it tested before you end up making a trip home with a buddy recharging your battery with jumper cables every 5 mins like me