I ran a charging system test tonight - if I don't use my XJ for a good few days the battery runs down (have removed the ignition off draw fuse as that only makes it worse). Today I started experiencing some slow cranking.

I may have just made it a whole lot worse - battery was low at 9.8v, test light on negative cable to post not lit, fired up (2-3 cranks over 10 seconds but ran normal) - upto 14.4v. So far so good....

So I checked the alternator by grounding the inspection tab (or what I think is the tab/hole). Screwdriver went in for a second, then I saw a small spark/arc, multimeter immediately started dropping and engine stalled.

Battery was 12.1v and all seemed fine - so I started up - no joy - cranking but not firing. Tried it 4/5 times over 10 minutes now left it so I don't drain the battery.

This is my only driver now so I'm really stuck..

I did everything by the book (Haynes Manual) but worried I may have cooked something...

Really appreciate any guidance

Thanks

 

Wow, good one Check the fuses well. What is it? year/engine?

 

1995 Cherokee, 4.0L LTD High Output, UK Spec, right hand drive..

 

first I would check EVERY fuse and pray thats what you blew.

 

It was the last but one fuse I checked - 'engine control2' under the hood - blown.

Replaced and started, thankfully...

won't be making that mistake again in a hurry...

Which brings me back to my actual problem - some circuit is draining the battery when left standing. I had huge problems with an aftermarket immobiliser a while back and removed the whole thing, not sure if the wiring has left a short somewhere. I've removed the accessories fuse (stereo, interior lights) as that was drawing a lot..

Any test method I can use to detect the fault?

thanks for your help...

 

Can you explaine what you mean by this? Never heard of grounding an "inspection tab" to test an alternator, and I've been doing this kind of work for many years...

Sounds like you blew a fuse. Typically if you fry an alternator it will not kill the engine... unless the battery is dead to begin with, which it doesn't sound like it is.

 

sure, I've uploaded the page from my repair manual where it explains the procedure - it also goes on to say some models have a newer style alternator which doesn't have the test hole....

I might ignore the wisdom of the manual in future....

 

If your meter will measure amps you can remove one battery terminal and put your system draw through the meter. The meter won't pass dittley without blowing a fuse or burning up so be careful what you turn on. When you measure amps you switch where the red positive lead plugs in the meter. If you forget it's moved and try to check volts it will be a dead short, melt your leads.
(it might be better to go through the negative side)

IIRC my 90 drew zip last I checked, but that doesn't seem right since the radio has a memory....... .2? 1/5th an amp? Or it might be less, Idk the figure. Anyway if it's high you can try pulling fuses to find it.