New and Interested in BIN Decoding

Matt here. Have a 98' GMC Sierra 350/NV3500 with original black box PCM 16250279. Have owned EFILive Flashscan V2 for a decade and a half. Originally purchased to tune fuel gauge level reading and adjust tire size calibration for larger tires in the past. Didn't do much tuning experimentation until purchasing a travel trailer 4 years ago and started chasing more consistent DFCO activation and getting rid of knock. Was able to sort of get the AutoVE tuning thing to work using the stock O2's and tweaked the main timing table until I was happy with the trucks performance towing the camper.

Didn't do much else tuning wise for a few years. About 1.5 years ago I got a motivated to solve the "buzzing" or "hummingbird" fuel gauge needle. EFILive never offered anything for the 98-00 Vortec PCM's regarding fuel system other than allowing to change the programmed tank volume (gallons). The guys on the (now defunct) PPE forum went down the rabbit hole with passive components (resistors/capacitors) and having to then rescale the gauge range (using HPtuners or others), but this never made sense to me. Instead I first borrowed a scope to understand what frequency the PCM drove the gauge at. Was basically able to figure out a PWM frequency of 59Hz from the PCM.
Attachment 18279

Then decided this would be a good opportunity to get into the Arduino scene and try to use an Attiny85 or Trinket or other to sample the fuel gauge PWM duty from the PCM and then drive the gauge directly with the Arduino at a much higher frequency. Scratched a lot of notes out, broke into the circuit from the gauge to the PCM pin (green wire under/around the brake booster/clutch master), grabbed a spare cluster from the yard to experiment with, and finally got something to work. I think I had the Arduino driving the gauge at around 32Khz or something crazy, but it was rock solid.
Attachment 18280 Attachment 18281 Attachment 18282

I then fell down the rabbit hole of trying to get a board prototyped that would include all the needed components that I could solder thru hole style myself. This was in the winter, and my next step was to actually purchase the board and figure out how/where to integrate it to the dash wiring harness. I had the thought to wire it into the convenience center box, but would need to pull the dash and its harness to do the job correctly. Camping season started and I lost interest again.
Attachment 18283 Attachment 18284

Happened to be browsing a GMT400 specific truck forum and saw a guy posting about being able to eliminate the typical fuel gauge buzz using JETDST. I had never considered the JET product, since it wasn't TunerCAT any longer (should have purchase software a decade ago) and I figured it couldn't do anything that EFILive couldn't already do. Apparently I was wrong, as he posted screenshots of being able to change the fuel gauge PWM frequency, and the stock setting is apparently 59Hz. This exactly matched the frequency I discovered myself with the scope. I quickly found someone selling the 14005 USB version with a single license left over, and grabbed it used.

I haven't done too much with JET yet, but have confirmed it can adjust the fuel gauge PWM frequency. Also interesting, is that a license is not used to read a PCM to .jcl file. I had read many times that a license is used just reading a PCM. This is not my experience. I also learned, when reading about the JET software, that it could save as BIN file format. This was very interesting to me, as I'd love to educate myself enough to be able to figure out exactly what parts of the BIN file are being modified when the gauge PWM frequency is changed, in order to ultimately learn how to write CAX files for EFILive. I've got an irrational desire to continue to try and make developments for the 98-00 Vortec PCM's on EFILive. Everyone else seems to have given up and always recommends swapping to the 411 PCM. I don't need to do this, but I'd welcome the challenge to open up more functionality on the black box PCM.

Anyway, very long intro, and now I am off to post in the OBDII tuning forum to see if anyone knows why I can't seem to get a good BIN file saved from JET. Or if anyone has other suggestions for pulling BIN files from Vortec black box PCMs, thru the OBDII port.

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Originally Posted by kawmatt2

Matt here. Have a 98' GMC Sierra 350/NV3500 with original black box PCM 16250279. Have owned EFILive Flashscan V2 for a decade and a half. Originally purchased to tune fuel gauge level reading and adjust tire size calibration for larger tires in the past. Didn't do much tuning experimentation until purchasing a travel trailer 4 years ago and started chasing more consistent DFCO activation and getting rid of knock. Was able to sort of get the AutoVE tuning thing to work using the stock O2's and tweaked the main timing table until I was happy with the trucks performance towing the camper.

Didn't do much else tuning wise for a few years. About 1.5 years ago I got a motivated to solve the "buzzing" or "hummingbird" fuel gauge needle. EFILive never offered anything for the 98-00 Vortec PCM's regarding fuel system other than allowing to change the programmed tank volume (gallons). The guys on the (now defunct) PPE forum went down the rabbit hole with passive components (resistors/capacitors) and having to then rescale the gauge range (using HPtuners or others), but this never made sense to me. Instead I first borrowed a scope to understand what frequency the PCM drove the gauge at. Was basically able to figure out a PWM frequency of 59Hz from the PCM.
Attachment 18279

Then decided this would be a good opportunity to get into the Arduino scene and try to use an Attiny85 or Trinket or other to sample the fuel gauge PWM duty from the PCM and then drive the gauge directly with the Arduino at a much higher frequency. Scratched a lot of notes out, broke into the circuit from the gauge to the PCM pin (green wire under/around the brake booster/clutch master), grabbed a spare cluster from the yard to experiment with, and finally got something to work. I think I had the Arduino driving the gauge at around 32Khz or something crazy, but it was rock solid.
Attachment 18280 Attachment 18281 Attachment 18282

I then fell down the rabbit hole of trying to get a board prototyped that would include all the needed components that I could solder thru hole style myself. This was in the winter, and my next step was to actually purchase the board and figure out how/where to integrate it to the dash wiring harness. I had the thought to wire it into the convenience center box, but would need to pull the dash and its harness to do the job correctly. Camping season started and I lost interest again.
Attachment 18283 Attachment 18284

Happened to be browsing a GMT400 specific truck forum and saw a guy posting about being able to eliminate the typical fuel gauge buzz using JETDST. I had never considered the JET product, since it wasn't TunerCAT any longer (should have purchase software a decade ago) and I figured it couldn't do anything that EFILive couldn't already do. Apparently I was wrong, as he posted screenshots of being able to change the fuel gauge PWM frequency, and the stock setting is apparently 59Hz. This exactly matched the frequency I discovered myself with the scope. I quickly found someone selling the 14005 USB version with a single license left over, and grabbed it used.

I haven't done too much with JET yet, but have confirmed it can adjust the fuel gauge PWM frequency. Also interesting, is that a license is not used to read a PCM to .jcl file. I had read many times that a license is used just reading a PCM. This is not my experience. I also learned, when reading about the JET software, that it could save as BIN file format. This was very interesting to me, as I'd love to educate myself enough to be able to figure out exactly what parts of the BIN file are being modified when the gauge PWM frequency is changed, in order to ultimately learn how to write CAX files for EFILive. I've got an irrational desire to continue to try and make developments for the 98-00 Vortec PCM's on EFILive. Everyone else seems to have given up and always recommends swapping to the 411 PCM. I don't need to do this, but I'd welcome the challenge to open up more functionality on the black box PCM.

Anyway, very long intro, and now I am off to post in the OBDII tuning forum to see if anyone knows why I can't seem to get a good BIN file saved from JET. Or if anyone has other suggestions for pulling BIN files from Vortec black box PCMs, thru the OBDII port.

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I found how to get a black box over 6K rpm. That being said I have two black box era GMs and both have LS controllers. The 99 Tahoe has an 0411 and my 97 Express a P59 running mexican L31 code. The only time I ever recall the fuel gauge on my 99 Tahoe being weird is during a reflash. The van has a seperate fuel gauge buffer module under the dash. That gauge acted for years until I put a new Delphi pump assembly. The OEM sending unit had a loose cobtact between the pivot arm and the rheostat.

Interesting. You'd definitely be an exception, if neither your 99 or 97 GMT400 platform vehicles had the fuel gauge seemingly lose its damping fluid and start vibrating. Take a look at the needle in this picture. Notice how it looks fuzzy, almost like its out of focus of the rest of the picture? Its because the dampening fluid (silicon?) has leaked out of the air core motor and now you can see the PCM PWM control because the frequency is low (59Hz). One seems to perceive it worse the higher the gauge reading is, I believe due to the duty cycle of the PWM signal. Closer to E, the vibrating needle is less perceptible. I read that 5-10 years ago, one could still find NOS fuel gauge motors that still had damping fluid in them to solve this. That supply has long dried up though.
Attachment 18295

So an update. A suggestion in my other thread in the TC OBDII subsection connected me with the creator of Tunercat. He graciously provided an update to the JET software that fixed the bin file read issue I was experiencing. This allowed me to adjust the fuel gauge PWM frequency using JET, read back out the bin file and investigate the changes in a hex editor.

With three different datapoint (stock, 120, 179hz) settings, I was able to figure out the factor the PCM was using to set the gauge driver frequency. Then I read up on creating CAX files in EFILive and made one of those for my PCM OS version. I will try flashing my truck's PCM tomorrow with EFILive with a few different frequency settings to see if I got it right. I don't have a scope anymore (was borrowed for pictures above) so I won't be able to directly tell what the actual gauge driver frequency is after my changes. I should be able to discern though if the hummingbird effect goes away, indicating the frequency has been increased. Using JET alone, at ~179Hz (roughly 3X59.5), the flutter is basically imperceptible. If my CAX file seems to behave correctly, I will share it on this site and EFI's forum. Fun stuff.

Hello! I'm trying to locate a .bin that I can utilize for a L31 & NV3500. Would the Mexican .bin you spoke of work? Thanks

Don't recall mentioning a Mexican truck bin. I may be able to help you however. I have attached a bin from my truck, pulled a couple of weeks ago. Note, this bin has the VE table, MAF curve, main spark tables, and DFCO enable settings adjusted for my particular truck. Perhaps if all you care about is the transmission segment (according to your other thread), none of those changes matter to you.

I've also attached an original tun file from this truck, I pulled a decade ago. This should be completely stock.

I've also attached an express van L31 manual tun file, that I downloaded a decade ago. No idea what else may be done to this one. I never used it.

I've also attached a tun file from an indicated L31 manual Tahoe. No idea what else may be done to this one. I have never used it.

Finally, I've also attached a recent ctz file from my truck just a couple weeks ago (should be same as the bin file attached) just in EFI format.

Hope some of this helps you.