Got the Volt Ohm Meter out and did some checking on my '94 Cherokee.
Automatic Trans, 4.0L drives and shifts good.
Cherokee Fuse F15 is good
Ignition off...
No voltage all pins
Ignition on...
Pin 86 12.55 volts, pins 85 and 87 show 0.01 volts, pin 30 zero.
Cherokee is also throwing the following CEL codes:
12 - Battery disconnected,
35 - Cooling fan relay,
21 - O2 sensor circuit,
33 - AC clutch relay,
51 - O2 sensor lean,
21 - O2 sensor circuit,
52 - O2 sensor rich,
55 - End code
History on the Cherokee is that it had a cracked head when I bought it last August, I've since replaced the head and gasket. I'm thinking that all the antifreeze out the exhaust destroyed the O2 sensor, thus the 21, 51, and 52.
I compared the voltages on the Cherokee with my '92 Comanche that has a similar PDC. The difference on the Comanche (besides the fan working) is that pin 30 has power at all times.
I'm thinking that, based on how the MJ is working, the PDC on the XJ is bad between the fuse and pin 30.
Any thoughts, opinions, suggestions or comments?
Thanks! Ed