xphnmn

I have a 94 LTI Vette. As you all know, the 94 has an OBD1 ECM but was equipped with an OBD2 diagnostic connector. I was wondering if it is possible to replace the OBD1 ECM with a later model OBD2 ECM and what would be involved in the conversion?

96GS#007

Sure. Like anything else it's a function of time and money.

You would need the added 02 sensor and Crankshaft Position Sensor (CPS) as well as the associated wiring and connectors. To add the CPS you need a new front engine cover. When you add the new front engine cover, you will need to purchase a new '95/'96 style Opti. With the new Opti you need to add the vent system. Of course you still have to address communications with the CCM and associated re-wiring.

It would be quicker and cheaper to sell the '94 and buy a '96.

Road Agent

STL94LT1

Why OBDII over OBDI?

toptechx6

Seems like many with 96 cars switch back the other way for ease of tuning, assuming emission laws don't play a part,
The only gains from going to OBDII is misfire detection and cat condition monitor. From what I see from posts here the misfire detection on the 96 is crude at best, perhaps because it was the first attempt. Just seems like a lot of effort for little gain to me.

pcolt94

Thats for darn sure and with all the other posts

Plus you would be giving up the on board diagnostics which works great on all the modules and you can invoke actions on systems but would need the FSM to know how to do that which most don't know about.

xphnmn

For the improved engine diagnostic capability and expanded fault code range.

DVNCI

If you plan on keeping the car indefinitely and you are just dying to do it, then go right ahead.

But if you ever plan on selling the car or modding it, OBD I is much more preferable.

My car is a 96' but was converted (thankfully) to OBD I before I bought it. But I like hacking/modding/playing with things so I like the OBD I a LOT better.

I think you will find it's probably not worth it - as stated above you will need a new PCM, harness, connectors, also probably a new CCM to make everything work right, otherwise you will get a blinking "SYS" light on your dash because the CCM recognizes the PCM is not the right year, think it's a Code 81 if I am not mistaken (my 96 still had the 96 CCM and I had this issue).

mike100

The other point not mentioned is that there are a lot more spares and junk yard parts cars to support the OBDI cars than the special one year only 96 stuff.

xphnmn

Thanks for the comments guys. I'll leave it OBD1. I'll admit I'm a newbie where working on computer equipped cars is concerned. One reason why I thought about making the conversion is that there seems to be a lot more and better scanners out there for OBD2 cars (not to mention that the only decent OBD1 scanner I've found is the GM Tech II and it's around $1500). I don't have a laptop so using one of the scanning software programs isn't really an option for me. Also, although they might work great for tuners, I really just want something for code scanning and maybe some data logging. Any suggestions that won't cost me an arm AND a leg? I hate to sound cheap, but I'm retired and money doesn't grow on trees for a retiree. PS I'm aware of the paper clip method of code retrieval but there has to be a better way than counting flashes of a light on the dash doesn't there?

96GS#007

Buy a used laptop with Windows 98 or Windows XP for $200 off of eBay and then go buy something like Datamaster for $100.

pcolt94

And this is one good way to go.

But just to add your thinking earlier 90s GM cars counting flashes as I have had a 90 firebird. But I don’t believe you are familiar with the on board system for code retrieval. There are no lights. Each module (CCM, PCM, Brake, SIR) system has its own designated module number and specific set of specific codes. It is displayed in the speedometer area as the read out.

There is lots of info on the Forum and the internet on it. But I will say that the FSM is the best information for facts and how to do it. Plus there is additional info you will not find on the internet. But you can get all the info on getting the codes on the internet.