What is the 4 character code on the ECM

**Ellas_Birds** · 04-10-2023

The ECM in my Bird has a 16202081 and BKNB on it. I backed up the BIN with FlashHack (great program) and when I look at the BIN I see the calibration, 16202081, but I do not see the BKNB inside it. What is the meaning of the BKNB?

Thanks.

**NomakeWan** · 04-10-2023

That's GM's internal code for the calibration. It was used at the assembly point as a quick and easy-to-see reference as to which calibration chip was which, so that the correct memcal could go into the correct vehicle.

**Ellas_Birds** · 04-10-2023

Thanks. I believe my ECM to be untouched from the factory and just wondering how to verify this. Should that code show up inside the BIN file? If not, is there anyway to verify that I have a factory BIN?

**NomakeWan** · 04-10-2023

That code is literally only for the person on the assembly line whose job it is to make sure the right calibration goes in the right vehicle. There is no other purpose for it, and as such it is not present in the BIN at all.

The only way to verify would be to use TunerPro to compare the contents of your BIN to the contents of a known factory BIN. Unfortunately here in 2023 I'm not sure if you can download 16202081 from ACDelco TDS, and I'm not sure it's worth $45 to find out.

I think it's better to just assume your BIN is factory. The chances of someone having messed with it are exceedingly low.

And frankly, even if that code appeared in the BIN, it would not be a good way to "prove" it was not tampered with. For example, the modified code on my two Corvettes retains the factory calibration IDs, but they are by no means factory BINs anymore.

**sanderson231** · 04-11-2023

The four letter code is known as the broadcast code. The same PCM/ECM can run chips with different broadcast codes. The difference between broadcast codes is the way the data and operating instructions are stored and scaled on the chip. I use Tunercat. In order to read the data on the chip the Tunercat program has to know how the data is stored and scaled. So a defintion file (.TDF) that is unique to the broadcast code is needed to tell the Tunercat software how the data is stored so that it can be displayed on a PC.

**NomakeWan** · 04-11-2023

Originally Posted by sanderson231

The four letter code is known as the broadcast code. The same PCM/ECM can run chips with different broadcast codes. The difference between broadcast codes is the way the data and operating instructions are stored and scaled on the chip. I use Tunercat. In order to read the data on the chip the Tunercat program has to know how the data is stored and scaled. So a defintion file (.TDF) that is unique to the broadcast code is needed to tell the Tunercat software how the data is stored so that it can be displayed on a PC.

That's not correct. The code you're referring to, the one that requires a specific definition file (XDF in the case of TunerPro, TDF in the case of TunerCats), is actually referred to as the "mask." For example, OP's mask is $EE, and thus he would need to use an XDF for $EE in order to make sense of the BIN file.

The four-letter code is merely a human-readable quick-reference of the specific calibration. As an example, my 1990 Corvette has ARFP. A 1991 manual Corvette would have had AXCN, and an automatic would have had AXCR. Yet all three of these calibrations use the exact same mask, which is $8D, and are all read using the same exact definition file as a result.

**steveo** · 04-11-2023

there used to be tools for this stuff like BCCFind but they are all broken. i'd recommend not caring at all about the letter codes for flash based ecms, they don't mean anything. they were the right way to identify your stock calibration with the old memcal stuff that's it.

**DavidBraley** · 04-11-2023

Sorry if this is a little off-topic. If it helps anyone, below is a list of BCC codes I found years ago. I found them really helpful (for the older stuff).

**NomakeWan** · 04-11-2023

Originally Posted by DavidBraley

Sorry if this is a little off-topic. If it helps anyone, below is a list of BCC codes I found years ago. I found them really helpful (for the older stuff).

Interesting! Oddly ARFP is listed as an automatic calibration in that PDF. Maybe because it was universal on the Y-body for 1990?

Thanks for sharing!