Okay here's the story I bought a 99 Ford Ranger with a bad 4.0 engine. I had a newer 2002 4.0 and tranny out of another Ford Ranger thought it be an easy swap put the newer engine in and it will only run on the original Older ecm (but ruff) and the older ECM is screwing with the transmission (no reverse) unplug connections at tranny and i have reverse. So I buy a ECM from a junkyard for the 2002 and drop it off at the dealership to have the Pats programmed. and the dealership says they can't program it to make it run. They say the Pats are different from 99 to 2002. So I go another route I buy an SCT performance chip and have them disable the Pats. still won't run. Any guidance would be greatly appreciated thanks

 

Welcome to FTE.
Those are two different engines, the 99 is a pushrod, the 2002 is over head cam, so seems to me you'd want/need the 02 ECM & GEM to make it run & shift right.

 

Are you referring to the Pats module in the steering column when you say "gem" ? Or is there something else I'm missing ?

 

GEM = Generic Electronic Module, its responsible for the control of a whole host of things that can be reviewed in post#8 by Ken00 here, https://www.ford-trucks.com/forums/1...m-systems.html
The GEM needs to be matched to the engine & tranny & probably the PATS system too.

 

I am just not sure which function of the GEM would make my engine not run or trans shift badly. Seems like all the functions are for interior items

 

The ECM is responsible for controlling the engine operation, one of the GEM operations is deciding when to shift the tranny, so those two need to be programmed & wired to operate together. I'm not clear on what changes Ford made in those modules between 99 & 02, but maybe a member reading this thread knows & will chime in with some detailed info. But as I mentioned, seems to me you'd want the 02 ECM & GEM so their programming matches the engine & tranny.

 

Thank you.... for your input I will get one first thing in the morning and try it out. where is it located on the truck?

 

On the firewall behind the radio.

 

just went thru the gem problem,,, someone had put a 2002 power window alarm system gem in my 99 ranger it dosent have power windows or alarm system,, the whole truck was pretty screwed up in some way or another,,, i have been going down list fixing my tranny problems,,, so make sure you get the right gem to match what you need,,,, remove radio then bezel, gem is on right side

 

The guys over at AAAEngine sell these reman for a little over 2000 bucks with a 2 year unlimited mile warranty and all gaskets. They do Zero mile engines with all OEM Parts. Check em out AAAEngine.com @ 818-900-8601

 

Okay now I have a new set of problems the gem module for the older pushrod engine has completely different wiring than the newer one. I did find a explorer with the 4.0 overhead cam and took the GEm out of it and it has the same connectors. Does anyone know if the explorer ECM and G EM will work in a ranger? Thanks

 

To answer my own question.... Yes a explorer ecm an gem module will work in a ranger. It had the same connections only thing I hAd to do was take it back to the dealer an have the pats reprogrammed. It didn't fix all my issues with the truck but atleast eliminated one variable

 

If the Ranger & Explorer had the same engine, tranny & GEM add on's, they should work. Good to hear you seem to have the PATS problem fixed. What still isn't right?

 

When i put the truck in reverse there is a about twenty second delay before it actually goes into reverse. If you go down to drive an quickly back to reverse it goes right in. It also cycles In an out of overdrive irregularly. I actually switched transmissions thinking I had a bad transmission. But the problem followed. It's something electrical, because if I unhook the large electrical connector on the side the transmission it goes directly into reverse with no problems, but doesn't shift right with that unplugged

 

OK, well since you like turning your own wrenches, maybe consider investing in a low cost ELM scantool & running FORScan, or the like software, as discussed here https://www.ford-trucks.com/forums/1...-scantool.html & have it scan the tranny computer for trouble code clues & post up All code Numbers.
Since the tranny has recently been changed, make sure the shifter control rod/s are mechanically ok & adjusted to the MFS & its properly oriented & fastened in place so that the cab shifter indicator & MFS are in sync, so the tranny is fully in the right gear. Check that the MFS pins/sockets & wiring to the Multi-Function Switch on the side of the tranny are undamaged, no corrosion & its electrical connector fits tight.
Make sure the tranny fluid level is right & the tranny has the specified fluid in it & line pressure is up to spec. Edit: If line pressure is low, drop the pan & check the tranny filter to see if its the right one, is installed correctly & not clogged with gunk. If pressure is low suspect the pump, or what ever clues the ELM & FORScan can find. If the OD light is, or has been flashing, the tranny computer has trouble codes stored & the ELM scantool can read them.
If still no joy, maybe consider changing the tranny MFS, as they're known to cause all sorts of weird mischief.
More thoughts for consideration, let us know how it goes.