Well This is probably a simple fix for a vetran xj owner but for me... every now and again the gauge that shows the voltage for the alternator just quits and goes to 0v and the check gauges light comes on. It just started doing this and i checked most of the wires soooo?
I am guessing that it is a sensor because the alternator was replaced last year. its a 2000 se model 4x4 4door with 147,000 miles, and a few mods.

 

Could be the alternator. Newer parts fail all the time, and the alternator is especially suspect for being in that category.

Verify connection tightness of all alternator connections.

If it continues, I'd suspect the alternator.

There is no sensor involved in this circuit.

 

The weird thing is it charges the battery great and all the connectors are good but i will double check them in the morning.
I just wanted to see if I could be pointed in some direction, but are you sure there is no kind of voltage regulator thing that tells the alternator to kick on or stay at a certain voltage???

 

do you have problems with start up? dimming lights when you're electronics are on & full blast??

you should check ALL of the wires....electricity has to be in a complete circuit in order to work

you could have one loose connection somewhere, whether ground or postive, whether on your battery, alternator, starter, or pdc....with engine & road vibes, the loose connection can be jigglin around, closing & opening the circuit

if all are good, get the alternator & battery checked.....alternator could fail within a year, its not impossible

voltage from the alternator to charge the battery is regulated in the computer (ecm/pcm)....if this fails, your battery will ultimately loose its charge & alternator wont recharge

inline fusible links (wire from alternator to pdc) protect the xj's electronics from amperage spikes....if these blow, you dont get power to the main fuse box (pdc) under the hood, & no electronics

 

Possible it is just a bad gauge.

 

if it is the gauge why would it only do it once in a while, and not just quit all together? an no there is no power problems, i do have a 15" kicker sub with a 1000 watt amp so it runs great.

 

Gauge would still do that. And it would charge just find. You might have a dead spot in the guage or maybe a bad or loose connection possible going to the gauge.

 

I would double check it while its doing it, see if it is charging. I would speculate if it is dropping all the way down it is a loose/ corroded wire to the gauge, or a broken wire to it, or a broken printed circuit board, or a bad gauge.

 

That could be my problem, I guess that if it doen't bother me then I will not bother it.

 

If it does it often I would take your meter and back probe the wire up by the gauge. If your meter is still getting the voltage but your gauge goes down and light goes on your just verified its somewhere in the gauge bezel. Might be the gauge or the circuit board but it is somewhere in there. If your meter drops too, start going back further and further until you get the power. You can't not worry about but personally I would like to know if my vehicle is charging or not. You could always run an aftermarket gauge as well.

 

Which wires would i have to probe? do you have a diagram? and if the gauge is bad, would that cause the check gauges light to come on?

 

From what it looks like in my book it is a Red/Blu wire but it looks like it is a common wire it shares for powering the rest of the gauge cluster so if that one is the only one that isn't working I would say the probablity is that it is either a gauge or cluster issue. My wiring diagram isn't that great though so I could be wrong about this one. And yes usually if it senses one gauge falls in the red it will cause the check gauge light to come on.

 

Well thats what I thought, just shoot me an answer if you figure it out.

 

Have had a lot of problems with bad grounds, make sure they are all clean. There are several you have to look around.