4 letter PROM code decoding
 

I am trying to get a new PCM off ebay and have found one I think I can use but the guy doesnt know what transmission it is for, can that be told by the PROM code? One time I say a post that decoded the 4 letter code but I have searched and searched and cant find it.

So anyway what tranny is used with BJLH?

I notice lots of them start with B, what does that mean?

One other thing, is there a difference in 5.0 and 5.7 knock sensors? I know there is a difference between 4.3 and 5.7's and napa lists different PN's detween the 5.0 and 5.7 sensors but can a 5.7 knock sensor ONLY work with a 5.7 chip and Vise-versa or will they work together?

Re: 4 letter PROM code decoding
 

Dan

BJLH calibration was used in 1994 5.7L TBI Burban, with $0D mask, in 16197427 PCM.

IRC, knock sensors (regardless of engine size) are tied directly into PCM (7427) as there is no ESC module. Knock sensors are tuned to have a specific frequency response - hence different engines may have knock sound frequency. Ask Rbob regarding KS and CalPack used in PCM's

//RF

Re: 4 letter PROM code decoding
 

How do you know that? I'm not doubting you, just asking where you found that info. I'm guessing one letter is the engine, one the transmission, one the tire size and rear end? Is there like a list of what all letters they use and what each one means in its location in the code?

Re: 4 letter PROM code decoding
 

To tell you honestly I do not, but this information is readily available! GM did not use intelligent part number scheme like some European manufactures do. That requires adherence to standards and discipline. Instead, general just used a sequential, ascending alphanumeric part number sequence. To know what one BCC was used for you either have to look up cal data or look into EEPROM contents.

With respect to BCC codes here are couple post worthy of (BJLH) mention:

https://www.thirdgen.org/forums/diy-...n-pcm-ecu.html
https://www.thirdgen.org/forums/diy-...questions.html
http://www.fullsizechevy.com/forums/.../t-212879.html


16196395 PCM was used in full size trucks and vans of various flavors which was superseded by 16168625 fallowed by 16197427. All of these PCM's use $0D bin mask definition. How do I know that, well in my collection of ECM/PCM I have 16168625 BHAZ; 16197427 BPRY; 16197427 BNKM which I have pulled myself from local JY from a burban, & 2x HD vans.

//RF

Re: 4 letter PROM code decoding
 

Two sites I have found valuable is DIY-EFI.org and craigmoates site under "downloads".