Pre-1991 alternator wiring question

My XJ has a Delco style CS130 alternator with the PLFS terminals plus the alternator output post.

EVERY article I read on the net speaks of running a resisted power lead to the "L" terminal and sometimes running the S to the output. My stock wiring harness gives no voltage to the "L" terminal but gives 12 volts to the "F"???????

The factory service manual is wrong in my case...it shows an alternator dummy light on the dash however there isn't one. There is no connector at that wire going into the back of the guage panel. (This is the wire going to the "L" terminal by the way)

Does anyone know the true wiring of the early model XJ alternators? It seems the factory wiring is different from everything I find on the net regarding these alternators.

Got gauges instead of an idiot light?

1988 FSM (Electrical) shows:

8 ga Red wire w/ fusible link from BATT terminal to battery

18 ga Yellow wire from I/F terminal (C205) leading to (Actually, coming from) "Engine Controls" and to the START terminal of the ignition switch

18 ga Tan wire w/trace from L terminal to connector C105, where it changes to 20 ga tan w/trace and goes to terminal 3 at C203, which is where it plugs into the instrument cluster, FOR IDIOT LIGHTS

Terminal 6 of C203 at the cluster is 12-volt power from the 7.5 amp Gauges fuse in the fuse panel. That circuit feeds through the volt meter to terminal 10 of C203. From there it is a 20 ga black wire to terminal 5 of C203, and from there it goes to ground.

I sure wish I had a scanner

The diagnostic tree is different depending on whether you have the idiot light or the volt meter, so the wiring must be different as well.

It would appear that the I/F terminal receives 12 volts from the ignition switch during starting, to excite the field. Once the engine is running the alternator doesn't need that external source, and it is disconnected when the switch is released to the RUN position. (However, that may not be entirely correct, because that same wire splits and feeds the gauges fuse. :dunno: )

I did some alternator research a while back, remember something about there being, various internal wiring configurations for the CS-130. They specified the F/I configuration for Jeep, the pre 91.
www.alternatorparts.com/cs130_sbpage1.htm explains things rather well.

EAGLE,

Your descriptions seem to coincide with my findings. The "I/F" terminal receives 12V from the ignition however it is receiving this voltage at the "run" position as well as the "start" position. Since I don't have idiot lights..standard guages here...the "L" terminal of the alt receives no signal.

So, my alt really only has two wires...the main output and the 12V sent to the I/F terminal...that's it.

This setup does not seem to be an option on any CS130 alternator wiring diagrams I have found...including the link above.

Another strange thing...with the stock setup the alternator will not function unless it first sees a voltage at the "output".

Is the jeep CS130 wired differently from all other CS130's?