: Question for OBD1 Guys: Can you pop an eprom out of your ECM?



botboy
01-13-05, 05:27 PM
I have a question for you guys with northstars from 93-95 with OBDI:

If you get at your ECM, can you pull off a cover or case of the ECM and remove a programmable chip (eprom)? Or is there also a calpack like on F-body cars? Can someone post a picture here? According to my Eldo/Seville powertrain manual you can remove the PCM Prom but it doesn't give very specific details.

I'm curious because I'm now setup to do chip reading and burning, and will soon be ready to do realtime tuning with an emulator.

I don't have a cadillac, just a northstar engine, which I want to make RWD when I'm done rebuilding, but I don't want to be fighting with the ECM and I don't want to pay the exhorbinant prices on systems like the holley commander 950, I think that the stock computer is more than enough to run the northstar reliably in a different configuration (like RWD in a small pickup truck) as long as it doesn't set itself into limp home mode because of the transmission.

Now, I've followed a few leads and gotten absolutely nowhere with guys claiming that they can get me a chip to eliminate the transmission controls that throw the ECM into LHM, but if I've learned anything in my 19 years the only person you can trust is yourself, SO:

1) I need pics of the PCM Prom from an OBD-1 Car if anyone can get me them

2) Does anyone know if the same ECM was used between 93-95 for the northstars in a specific app (like the STS for example) or across all northstar-equipped vehicles? Part numbers if anyone has them?

3) I would eventually like to start a chip index for the cadillac ECM's as the GMECM website has done with the 7747/7730 ECM's and the F-body guys have done with the TPI ECM's, to make it easier for people doing the vin Y cam swap to change the computer settings, as well as establish a knowledge base cadillac ECM information and bin files....anyone want to donate any parts (Proms) to the cause or any information they can scrounge? My email is botboy60 (at) hotmail (dot) com if anyone has anything of interest.

4) The eventual goal of this project is to get an ECM knowledge base up on my website, www.speedyoldtruck.com (which is currently down), but furthermore to get together a datalogging definition file for tunerpro and maybe even a realtime programming definition for tunerpro or tunerproRT for those of us who are doing our own chip burning and tuning.

5) I'm also looking for an engine harness if anyone has one they would sell. I have a '97 SLS interior harness and dash cluster I could trade for it, or maybe pay cash in the near future.

Thanks for anyone who can help me out, again my email is botboy60 (at) hotmail.com.

caddydaddy
01-14-05, 08:10 AM
The EPROM pops out after you remove two clips on the side. The codes for them are model specific, so each car can have a different code.
Check out www.superchips.com, I'm sure they have a pic of the GM style EPROM that Cadillac uses as well.

oldgamer
01-14-05, 12:52 PM
I changed my old bad PCM with another one and was able to remove PROM from old one pretty easy. The PCM has a two screw on a top of cover. You just need to unscrew it and pull out PROM using two clips (almost like in your PC).
The PROM stores engine ID and transaxle ID. It can be verified pulling out data codes PD99 and PD99.

botboy
01-19-05, 04:48 PM
The EPROM pops out after you remove two clips on the side. The codes for them are model specific, so each car can have a different code.
Check out www.superchips.com, I'm sure they have a pic of the GM style EPROM that Cadillac uses as well.


I feel kinda dumb asking this, but where did you find it on superchips site?

Also, does anyone have any or know of any .bin files scanned from OBD-1 northstar cadillacs?


I changed my old bad PCM with another one and was able to remove PROM from old one pretty easy. The PCM has a two screw on a top of cover. You just need to unscrew it and pull out PROM using two clips (almost like in your PC).
The PROM stores engine ID and transaxle ID. It can be verified pulling out data codes PD99 and PD99.

Yes, the prom stores engine and transaxle ID, but it also stores values pertaining to emissions, shift points, spark advance, error codes, LHM, fuel maps and a lot of other things, and reverse-engineering the .bin files you can scan out of these chips would get us OBD-1 guys a lot more options for forced induction, tuning, and engine swaps.

caddydaddy
01-20-05, 07:54 AM
[QUOTE=botboy]I feel kinda dumb asking this, but where did you find it on superchips site?

I was just guessing they did. Maybe they don't. I'm sure you can find a pic on the web.

oldgamer
01-20-05, 09:20 AM
...Yes, the prom stores engine and transaxle ID, but it also stores values pertaining to emissions, shift points, spark advance, error codes, LHM, fuel maps and a lot of other things, ...
Sure, I know. I just mention that that data is important for identification of software. My advice is to write down these two codes before pulling out PROM of the PCM.