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Yep the 07 is the p12b 2mb. I was able to reproduce this last night and I think the timeout is borderline too short for the larger sectors on the amd flash chip with the xpro timeout calcs. I'll try and get this sorted soon and send you a test build.

Yep! I was able to reproduce exactly that by building locally and debugging. Stepping through line by line I got a success response from the kernel and was able to write! Now I have 2 happy P12 pcms

I'm still willing to test that fix to confirm - hopefully it'll help others!

Bingus wrote:Yep! I was able to reproduce exactly that by building locally and debugging. Stepping through line by line I got a success response from the kernel and was able to write! Now I have 2 happy P12 pcms

I'm still willing to test that fix to confirm - hopefully it'll help others!

If using the OBDX Pro VT on Bench for some of these older style ECUS like P12/P04 ect, we found that you may need to add a pull down resistor (connect resistor between VPW and ground) to help with communication stability.
This is due to those style ecus were typically in vehicles which had multiple modules that would all pull the bus down slightly (loading the bus) which acts as the method for pulling the VPW line low. Without these pulldowns, some modules will 'float' there VPW voltage back to ground which can cause stability issues at high speed as this takes too long.

Quick fix for this is adding a 2k-5k resistor from VPW pin to ground.

Some J2534 tools may apply a slightly stronger pull down inside the tool which also accommodates to this, so may not be needed on something like a GM MDI.

Tazzi,

Does the (sometimes) need for a pull-down resistor between the VPW line and ground need to be close to the ecu? Or can it be an addition to the bench harness?

A switched resistance path between the VPW line and ground would be super easy to add to a bench harness.

I only have the pull down for the VT, and mines near the scantool
Itself, but I believe it could be done anywhere in the harness.

This all only applies when using a bench harness with the VT.

I will just add that I havn't needed this with my VT, so its not an always thing either. Also I am having trouble with the first write packet on P12, but I think it is something else as I have added that resistor and it made no difference for me. I am testing the new asm kernels that are not released though. I still think its a timing issue, but I don't know for sure yet. I'd like to get this new asm kernel issue solved as I think all other issues are solved with it and it'll be good to look towards the next pcmhammer release supporting P04 and P08 as well.

antus wrote:I will just add that I havn't needed this with my VT, so its not an always thing either. Also I am having trouble with the first write packet on P12, but I think it is something else as I have added that resistor and it made no difference for me. I am testing the new asm kernels that are not released though. I still think its a timing issue, but I don't know for sure yet. I'd like to get this new asm kernel issue solved as I think all other issues are solved with it and it'll be good to look towards the next pcmhammer release supporting P04 and P08 as well.

If it is timing, it can be adjusted by commands to the VT also if thats the case

I would expect seeing issues trying to upload a kernel/loader if timing was a problem though for large chunks. Maybe looping through uploading a chunk of data to the ECU over and over could test the theory?

Yep its just time. It all fundamentally works - it probably just needs a small tweak... in the right place.

antus wrote:Yep the 07 is the p12b 2mb. I was able to reproduce this last night and I think the timeout is borderline too short for the larger sectors on the amd flash chip with the xpro timeout calcs. I'll try and get this sorted soon and send you a test build.

Can you confirm the 07 actually has 2MB? GM talked about releasing a 2MB P12, haven't seen one yet (but want to be proven wrong here)!

Here is the bin I pulled from the 07 P12b I have. It is indeed 2MB.

It also took a lot longer to read due to failures - wondering if the resistor trick would help. I'm surprised at how unstable the P12b read was compared to the P12 I have.