I have a 1999 3.0 5 speed 4x4, bought a few weeks ago , the other day the speedo and odometer stopped working, no abs light on. Some days it works, some days it stops working well driving and somedays it doest work from starting it. Replaced the rear abs sensor and pulled the gauge cluster yo check for loose wires, still the same. Thoughts ?

 

Welcome to the forum

The 1998-2000 Rangers used the rear axle ABS sensor spliced to the GEM module(behind radio)
GEM module converts the 30,000ppm ABS signal to the 8,000ppm speed signal the computer, cruise and speedo/odo need
PPM = pulse per mile, just FYI

Yes, with no ABS light, assuming bulb works, rear axle sensor is probably not the problem

Computer should set a P0500 code if it loses speed signal from GEM, can you check for codes?
If both speedo and computer lose signal then GEM or its wire from ABS sensor could be the problem

If no P0500 code then cluster is most likely issue

Do you have cruise?
If so try to see if it dies when speedo does, that would point to GEM

 

it has aftermarket cruise control , it works when the speedo doesn't. Seems to be totally random

 

And no CEL(check engine light) and P0500 code?

If not then the cluster is the issue, 1999 Ranger can use a cluster from a 1996 to 2003 Ranger, plug and play

 

dumb question, to check for the P0500 code I can just use a loaner scan tool from any auto parts store ? Does the odometer have to be not working at the time to get the code ?

 

Yes, any OBD reader will see that code, and it will be in history at least, if it ever happen to lose speed signal

No it doesn't have to be missing the speed signal at the time you have codes read

OBD reader automatically show "current codes" if CEL is on, but also shows past codes, history codes, which would have P0500 if computer lost speed signal at anytime in the past

Have a pencil and paper, WRITE DOWN any codes, "I think the code was XXXX", is worse than no code at all, you end up chasing your tail

 

Here's the code screen

 

So it looks like the issue is in the cluster

Its possible, but unlikely, that the 1 wire from GEM to cluster is intermittent
If you want to pull the cluster and Radio out you can test the wire, or run a new wire just to be sure

Diagrams below, 2000 and 1999 are the same for this

Instrument clusters center connector, C215, Pin 1, grey/black wire is the Speed signal from the GEM module
Have a look at that pin, it may not be making a good connection, its been push out of connector a bit

Gem Module Pin 1 on 18wire connector C224, also grey/black wire, is the Speed OUT signal that is spliced to the cluster and computer, and maybe Cruise in your 3rd party setup
This connection is OK since you don't have P0500

 

My speedo and odometer were doing the same thing. I ended up getting a used cluster and replacing it. No issues for about 8000 miles now with the replacement cluster.
Jim