Reatta PROM

[kdirk]

Ronnie,

 

No problem there. I was unaware of the loss of old user accounts, and kind of threw me off a bit since I knew I had the right username and password. No matter, glad to be back on board. As Dave gave me a heads-up via email regarding this post I figured it best to hash out the details here for the benefit of adding it to the knowledge base.

 

Now I'm trying to determine which codes are valid for 1990, which are federal and which are California. I have a few factory original units on hand and can reprogram one to contain another version provided it is one I have a copy of already saved. A California version is probably the most difficult to find as these were only installed on cars originally destined for delivery and sale in California. I don't think I have a copy of that one for 1990 (or any hear for that matter) but will look. If not, I can supply a federal 1990 PROM for certain.

 

Kevin

[kdirk]

Ok.

 

 I have found GM TSB that gives PROM applications by year and model. An excerpt follows.

 

1990 Reatta - Federal emission - calibrator scan code 8064 (this is AYTH as far as I can tell)

1990 Reatta - California emission - calibrator scan code 8074 (no letter codes are given in the TSB and I don't know what this one is)

 

Interestingly, 89 LeSabre and Electra (which shared a common PROM) does not list 5945 as a valid scan code in the TSB. The parts listed are scan code 8004 and 8094 for Federal, and 7994 and 8014 for California. Again, no letter codes are given so I cannot cross reference these. Further, both 1989 and 1990 model LeSabre and Electra used these same PROMS, with no difference between the two years. The reason there are four PROM versions is that there were two different axle ratios offered, 2.84 and 2.97 on the LeSabre and Electra. All Reattas and most Rivieras (excepting 1989 models which had 2.84) came with 2.97 axle ratio standard.

 

Yet another oddity is that I have a MEM-CAL here with a PROM marked AYTK/8084 which the TSB shows as being for a 1990 Riviera, Federal emissions and a 2.97 axle ratio. How this differs from the 90 Reatta federal PROM, which is also 2.97 axle ratio, is anyone's guess. I had thought it was for a Reatta (and would probbaly work fine) but is officially spec's for a Riviera.

 

To confuse the issue even further, many 89 and early 90 Buicks with the 3800 had a problem with extended crank at cold engine due to a bad fuel multiple setting in the factory PROMS, which is the subject of the TSB I referenced above. Presumably, these PROMS had yet another set of letter and number codes that are not shown in the TSB, only the (then) current replacements by year, model, code and part number are listed. Perhaps the one with code 5945 is the early 89 PROM with the bad fuel multiplier setting for a LeSabre, but I have no wayway to confirm that.

 

Now that I have hashed that all out, I need to see what I have that will work. I suspect the best I can do is supply a 1990 Federal version, as the California  PROMS are exceedingly rare and I don't believe I have copies of them to burn a new one. All my PROM stuff is on another computer so will fire that up and see what I have available. Stay tuned.

 

Kevin

[Ronnie]

At one time, back when Mc_Reatta was still on the forums, it was determined that this was the correct listing of PROMs. If it is incorrect or changes are needed please let me know.

 

ECM PROM List

[Ronnie]

Oops. I see you were posting while I was writing.

[kdirk]

Ronnie, thanks. I knew I had seen a listing somewhere before, but couldn't find it in looking at my own files and searching here or over at the other forum earlier. So, it appears I have a stock 90 PROM early version federal, ANWU. The big question is whether I have or can get a late version Federal or California. Off to go digging...

 

 

Kevin