I have been doing a little research, as this matter comes up often , and I have 3 x '96.

I have come to the conclusion that if you have an OBD2 port, in the vehicle, you have OBD2

As per FSM, OBD1 has a port in the engine bay

My modern scanner is trying to tell me that my 4/96 has OBD1, and it wont read codes..however, if I plug my old OBD2 scanner in, it reads 0138, and my rear O2 sensor has its wires cut

as far as I can tell, an OBD1 system simply cannot generate that code, meaning I must have OBD2, no matter what my new scanner is trying to tell me

any further info is welcome, and I have seen supposed ways of telling them apart, but to me an OBD2 port is the give away

I believe OBD1 scanners each had a different port type for each car maker.

btw, my new scanner works on a late model vehicle, and picked up codes, my old one showed nothing...but has worked before to show codes and clear engine light on that vehicle, and my 7/96 XJ

 

Sounds reasonable to me. I have a late year '96 which is definitely ODBII.

 

Both of my 96s have a JTEC pcm and are obd2. I would use the ecu type to verify obd1 to obd2.

 

In the states it was federal law that vehicles manufactured AFTER Jan 01 1996 have OBD2. While it's possible that an export vehicle made after that date could use the old system, it's unlikely.

If you have a P type code it's definitely ODB2.

 

In other words, the slim silver box PCM is ODB2.

The black box with the air vent PCM is ODB1.

 

SBEC2

 

This is interesting. I have a 94 chassis and electrical system and a 96 engine. I have an OBD1 port near the pcm under the hood. The jeep is currently working...after an extended hiatus of failures...should I switch to a 96 pcm or is that just like asking for trouble? Anyway I bought this funky OBD1 to OBD2 adapter cable that I thought my mechanic could use...it would power up his OBD2 scanner but he kept getting com errors. I told him that won't work. He also has a giant Snap On but said he does not have my car in the program. Interesting cable though....like 8 bucks on ebay I just gave it to my mechanic.

 

You should keep the current PCM. The engine itself is pretty much (if not exactly) the same from 94-96. You can't just throw any PCM into your Jeep, you need to match the part number. Granted, my 95 had the incorrect PCM in it and it ran fine. I swapped in the correct part number and there isn't a noticeable difference in operation. Both were the black box with the air vents (or SBEC2), of course. If you want to swap between an ODB1 and ODB2 system, it's not a trivial swap. I'm sure it can be (and has been) done successfully, but I'm sure it was time consuming and not fun.

 

Thanks for the quick reply on that one. Yeah I figure if it ain't broke don't fix it...especially with my jeep! Well with a few exceptions. I still wonder what application could use that cable? Is there a monster scanner that does OBD1 and OBD2? If it did it would probably have the plugs for both applications anyway. Hmm Deep thoughts.

 

No prob.

There's really not a good reason to buy an expensive scanner for the ODB1 for anyone but the professional (and these days, maybe not even them). Unlike the ODB2, you can't get the "real-time" data and if you do get a code you can retrieve it easily with the key trick. You're much better off getting the few specialty tools to get the kind of info that you need - IR temp gun, multi-meter, etc.

 

My 96 was built Feb 16, 1996. OBDII

 

Some obd1 readers can display live data. There are specific plugs for each vehicle make. Jeep XJs from 91 to 95 use the DRB3 connector.

 

I suppose I should have said, inability to easily read live data.

 

there was a guy on the Australian Forum who was an auto electrician and converted his owned from new OBD1 to OBD2.
I dont know why he did this, and unfortunately he recently sold it and left the forum, he was our forum auto electrics guru

by searching that forum, it would be possible to find out what he did, I will have a quick look

I personally would be hesitant to attempt this, unless you have a lot of auto electric experience.

will make a further comment on computer part numbers later

 

Snap-On MT2500 does OBD1 and pre-OBD1 (Renix) and has live readout for both. I found a used one on eBay with a bunch of different modules and it has no problem producing live readout on older vehicles as long as I have the correct connector(s) and module. I also have some modules that work with non-US foreign vehicles.

OBD1 was invented and develop by CARB https://en.wikipedia.org/wiki/On-board_diagnostics

Sometime back in the early 90s some auto manufactures such as Jeep switched to OBD1. (from the Renix PCM). OBD1 was sort of experiment for it's predecessor OBD2 officially developed by the FED but I think CARB helped the Feds develop OBD2. Where the Feds were able to standardize OBD2 and create a Federal mandate.

OBD2 was developed and created to standardize OBD for all vehicles manufactured in the US. There are also some pre OBD1 and Pre-OBD2 OBD that can perform live readout if you have a compatible scanner and adapter. Such as GM's ALDL (Assembly Line Diagnostic Link ) at least for some years vehicles is capable of live readout. Was the closest thing to a OBD standard prior to 1991. I remember reading ALDL is capable of live readout, uncertain which years, sometime prior to 1996.

However I think each manufacture could perform live readout using their own scanners. I'm uncertain which years live readout actually started as each manufacture had their own propriety scanning equipment. Timeline probably varied from one vehicle model and manufacture to another.

Most consumer scanners that are OBD1 / OBD2 basically only read any stored codes for OBD1, unless you want to spend starting around $500.00 for a professional scanner. Many professional scanners such as from Snap-on start around $2K on up to over $15K. You can pick up used ones for less, but costwise the MT2500 (which is originally a professional scanner) has alot of functions and features, even some test procedures, etc. for older vehicles. Also does OBD2 up to a certain year, depending on the module.

Chrysler DRB-III handheld scanner new runs around $6K, it and compatible DRB-II and III scanners are the only scanners capable of full scanning, testing and diagnostics of Chrysler vehicles.

If you want live readout for the Jeep and other manufactures, a used MT2500 Snap-on costwise is the way to go. You just need the correct MT2500 module and pre obdii adapter for your year vehicle. Often the adapters need to be connected to a 12 Volt power source as OBD1 and pre-OBD1 don't normally supply power to a Snap-On MT2500 similar to OBD2 scanners.

I use to have a 1988 Ford Econoline but never could achieve live readout with the Snap-On MT-2500 I think this was due to Ford was far behind other auto manufactures back in the 80s and 90s. I'm uncertain if their 88 ECU was capable of live readout as the Snap-On MT-2500 even though had the correct Ford Module and plug adapter there was no live readout. Was only able to perform a few basic tests.

Perhaps a Ford had their own propriety scanner for that Era with live readout? 1988 is pre-OBD1.

Anyway aftermarket scanner manufactures need to pay for any proprietary information for each auto manufacture and model line. That's one reason why the professional scanners cost much more than consumer scanners. In 1996 all the US auto manufactures needed to change their ECU's to include OBD2 but are allowed to keep their proprietary functions and features that normally can only be usually accessed by more expensive professional scanners . Some consumer scanners do have a few proprietary functions for some vehicles but it's very limited what a consumer actually do compared to professional scanners.