I put a 92 engine (complete minus exhaust manifold) into a 90 limited. For some reason the alternator is not showing any output voltage. I am not sure if I have it wired up correctly or if I need to swap out the alternator with my 94 cherokee to see if it is bad. Has anybody else done this alternator swap and know how to wire it up?

I have schematics for each one just not sure about the wiring.

the 90 has these outputs:
+ that goes to battery
yellow wire goes to ignition switch
tan wire that goes to instrument cluster

the 92 alternator has these outputs:
Drk grn wire goes to power control module
drk grn/org goes to automatic shut down relay
negative cable to block
positive cable to battery

I am not sure how to hook up the 2 wires on the 92 alternator.

 

I compared voltages on the wires on my 94 cherokee going to the alternator and had -6vdc and -12vdc. The voltages on the 90 cherokee going to the 92 alternator(same vehicle) where -12vdc on both wires. I am thinking the inputs should be good to activate the alternator. I am now thinking it could be the altornator is bad. It was a complete engine from a jy and I used the alternator that came with the engine.

 

There's an easy answer here - and a couple of solutions.

The easy answer: The 1990 uses a Delco CS-130 alternator with an internal voltage regulator. The 1992 uses a Nippondenso alternator with an external voltage regulator. No regulator signal = no alternator output (and wiring the field coils to full battery voltage will blow out most of your electronics, so go ahead and forget that approach...)

Solution #1 - Install the Delco using bracketry from the 1990, and maintain original wiring. Problem solved.

Solution #2 - Add an external voltage regulator to drive the Nippondenso alternator, and modicy wiring accordingly. Here's a "Here's How" for a Prestolite marine voltage regulator: http://www.geocities.com/JeepI6Power/presto.html (Ignore the bit about the "hard code" being set doing this - RENIX doesn't do anything with DTCs, being pre-OBD. That note is included for owners of 1991-up rigs.)