04 gmc 2500hd 6.0L no communication while doing ckp relearn or misfire data watch

dave edward · May 24, 2023

Hey all. I have 04 gmc sierra 2500hd. It has the p0300 code and I have an autel maxidas ds708 scanner. I have tried to do the ckp relearn with cgsulit scanner first and it had a no communication issue, when attempting the ckp relearn. I figured it was a bad scanner, returned it, and picked up a autel maxidas ds708 to do the relearn with. I got the scanner in finally, updated it fully, and attempted ckp relearn again. As it does the procedure I will go through the process, and right at the end, it will tell me that there is no communication. Tried multiple times and restarted etc, still the same issue. So I'm thinking their is a wiring issue, a break or an exposed wiring, maybe even a bad ground. Possibly a bad ecm at worst case. I was fiddling around with the scanner options, and i can watch live data on fuel injections, compression, read/erase codes and basically anything else with 1 other exception, and that is the misfire live data watch. It will start to show the data then no communication will pop up after 1-2 seconds. I see the data start pop up then no communication. Now I do know that it had a data communication fault at one point but it was solved due to a bad ground, and no more issues after that according to the previous owner and that was 8 years ago or so when that was fixed.
So I'm wondering if any of you have had this issue before and what possibly fixed it. I'm thinking I will have to track down a break in the wiring to the ecm or ckp but im really hoping its not that, because its never fun to do track down a break.

Thanks for the help.

David89GMC · May 24, 2023

Why do you think it's the crank sensor?

A broken wire will prevent communication, not lose communication after it's working. A poor connection might cause intermittent communication, so check all your connections.

That China-made scanner may very well be the problem. There may be a good reason why it's a discontinued product.

Get a different scanner and try again.

try this link

dave edward · May 24, 2023

56 minutes ago, David89GMC said:

Why do you think it's the crank sensor?

A broken wire will prevent communication, not lose communication after it's working. A poor connection might cause intermittent communication, so check all your connections.

That China-made scanner may very well be the problem. There may be a good reason why it's a discontinued product.

Get a different scanner and try again.

try this link

Due to the P0300 code which is a random misfire code. Everything i have looked up, whether its on this forum, other gm forums, youtube, or just searching on other forums. this generation of 4.8l, 5.3l, and 6.0l have this code issue, usually after spark plug, wire, and coil changes have a random misfire code P0300 that only goes away after doing a crank relearn via scanner. You may want to blame my scanner but this is one of the only scanners that can actually do it. I don't have access to a gm tech II, and this specific scanner was shown by several mechanics on other forums, or even showing how to do it on youtube using said scanner. So the issue I doubt is the scanner, and I cant find many others that can do this, also its discontinued because they upgraded the model to the maxidas ds808 and its variants and this is older hardware but unfortunately the newer scanners only are capable of dealing with newer vehicles. I have confirmed this directly with the company and they recommended a $1400 scanner, couldn't confirm if it actually work on an 04. So i had to find a decent used one for sale, which I did find a like new condition, so i snagged that since it was a good investment and fully updated the software. I talked to Innova as well and they don't have one that will work on an 04, and tried a few other companies, and simply couldn't find a useable one.
A wire can break, without breaking the casing, causing communication issues while being stressed during certain functions and working with others because it has an intermediate connection by the break touching. I see this occasionally with forklifts and cranes. You are certainly right but my own personal experience with other machinery can give exceptions, but I should go through and double check all connections, clean and reseat them to make sure they are 100%. I'm just curious if anyone has come across this particular issue and wanted to see what they did to fix it, whether they found a bad spot in the harness, a broken or extremely dirty pin, or maybe the wiring to the ckp was bad but the ckp codes were not coming up. I'm hoping to narrow down some choices a bit better.

Edited May 24, 2023 by dave edward
saw an error

davester · May 25, 2023

I haven't had a problem like this, but I would suggest getting a knockoff MDI unit (usb-obdii passthrough device), and use it with Tech2Win on a windows laptop, to do this work. It's the dealer-level solution, and a LOT cheaper than $1400...

I bought one from here https://www.chinacardiags.com

along w Tech2Win and it works great with my '12 Silverado 3500 (haven't needed to use it w my '04 yet). It's advertised on the site as an MDI 2, but it's an MDI 1 in an MDI2 housing. But, it uses the oem Bosch driver and firmware, so it has good, long term support by the oem manufacturer, and it can do all the diagnostic tasks and access all the computers in the truck.

Edit:

As well, w a subscription to ACDelcoTDS (relatively cheap), you can also reprogram all the computers and perform various dealer-level tasks, such as getting a vin-locked radio to work w your truck.

Tech2Win works up to around '13 for trucks, then GM switched to GDS2 diagnostic software (which also works with the MDI unit) for newer vehicles (the exact cutoff year various w the vehicle, as GM didn't switch all the vehicles over at the same time).

Edited May 25, 2023 by davester