Bob. Interesting VSS problem with your 98 Ranger. I do not have answer for you but a question since you seem to be so well versed in the subject. I have a 98 Ranger that I have installed a 1991 Crown Victoria 5.0L engine and PCM. The Ranger speedometer is not working and the wiring diagram shows the RABs signal to the GEM module and the corrected signal goes from the GEM to the speedometer, the speed control and the PCM. All 3 feed on a parallel circuit from the GEM. The speedometer should work. Unless the GEM software is looking for a connection with the PCM before it will send the signal to the speedometer? Other than the speedometer all of the GEM functions appear to be working. Any thoughts are appreciated. Thanks.


Mods Note:
Please don't hijack other member's thread, now you have your own,

This thread was split from --
Failed frequency modulating from VSS to PCM-1998 Ford Ranger Generic Electronic Module (GEM).

 

As you haven't changed anything else in this circuit, I'd say the PCM doesn't like what the GEM's sending it. These GEMS are very vehicle-specific, and the one in '98 Rangers is more specific than others. I think it was used in only a few model years, and fewer models. The 4WD 1998 Ranger GEM is not the same as the 2WD. Find out what kind of signal your PCM wants and see if you can modify the GEM's output to suit. That's what I've been trying to do, with no success yet. Ford says its SCP network does not interact with the SAE network, but it does, and this circuit is what bridges the two.

I'm still fighting mine and I'm way, way behind in adding more information to my post.