.458 - Have you had a repeat failure?? I'm in a 2000 Sahara Wranger, having the same issue. I am not an electronics expert, but I had access to Mitchell on Demand from a friend. Here's what I've done so far:
1) Check battery - good per O'Reilly Automotive
2) Replaced alternator - No change in performance. I did not take my core in after reading threads so I pulled the new one, reinstalled the old one, and got my $215 + core back. I have the 117 amp alternator (frame ground, 2 wire [green w/orange stripe & "dark green"], 1 big red one)
3) Checked for voltage from "generator field driver" (green/orange stripe) to ground- got 11.81v. If it matters I chose the alternator frame as ground for my cheap multi-meter probe.
4) Back probed (paperclip) "generator field driver on generator field connector terminal 2" (Dark Green wire) - got 338 mV
5) Ohmed the terminals in the alternator - 3 Ohms (lower than the spec of 5 I was given).
6) Ohmed from PCM terminal C (grey plug) pin 25 to both the dark green and green/orange stripe (because I'm not sure which wire from the alternator traces to C25). In both cases I got no response from my meter. It stared at me with a blank mega ohms reading.... so I guess my next step is to tear apart the wiring harness to see if it's broken/shorted?
If I run a jumper wire from whichever wire (drk grn or grn/orange stripe) behind the grey terminal and splice into the corresponding wire in the alternator terminal - Will I damage anything (provided my splices are good). I am thinking if I ran a jumper as a test it would tell me if the wire was actually broken/chaffed/shorting/etc. I envision using something like these: http://www.wiringproducts.com/conten...ick_splice.jpg
My concern is that any of the following are true - my paperclip probes weren't up to snuff, my techniques for troubleshooting weren't as good as possible, my homedepot $40 digital multimeter may not be up to the task (but it seems to work nicely), that I'll end up in the PCM boat with a bunch of others AND possibly have made unnecessary splices.
I'm very interested in anyone's thoughts before I start ripping up the wire looms to determine if I have a short or running a jumper wire.
.458 I'm MOST INTERESTED to determine if you actually troubleshot to root cause of failure (understanding that the assignable cause of failure is, as you mentioned above, a part of the circuit board of the PCM which I'll have to dig up an applied electrical engineer to get fixed).