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Well my fans came on high by themselves (PCM) for the first time the other day since we have finally got into summer temps (90s to 100+ F) so it can command high speed. I have A/C blasting pretty much every time I am driving now, but I was watching my ECT via torque app and it got hot enough for them to kick onto high so I think it was that, and not A/C trigger.
Hmm, I might try using the BP automotive instead of a relay setup. PCM of NC sells a sub harness to control the high speed fan based off of the A/C using a circuit board that is triggered off the positive A/C and converted over as a ground. But I wonder if changing the settings from analog cycling to either analog or serial cycling may allow the fans to kick over to high based on pressure settings. ( I stand corrected, this was outlined by the OP in which you need to use Analog so it is similar to that of the Camaros in regard to the pressure sensor)
but I’ll have to look and see if those pins are already in use on my 01, or if they are unused, as that would simplify things some during the install.
Watching this too..... work got the best of me so my 99 Sierra has been sitting in pieces for over a year. I did install the sensor harness but I tried also installing a newer 411 pcm and was having issues there and dont really even remember exactly what anymore. I put the origial PCM back in though and (selecting a newer truck) with a Tech2 can manually make the fans come on both low and high. I also have full EFILive too but never did get back around to doing more testing. Something also is toasting instrument clusters - 2 damaged Escalade clusters.
I did know that the fans at least came on low just letting the engine get up to temp though. Really want the ac head pressure triggers to work properly.
On my 2001, I had to upgrade the OS to 12212156 from a 2002 truck. Otherwise my fans would come on as soon as I started the truck, but I could manually control them with a tech2, it was a bit annoying to get figured out to say the least. But with that OS the come on with the temp and will turn on low with the A/C, but want to get it to go to high like my 04 does
damn, what is your new PCM out of? Did you make changes in regard to charging using a tuner? I wonder if that is causing your cluster to burn up if it’s configured for a newer truck and not the 99 setup
I don't think the instructions for the BP Automotive kit have been posted here, but here they are. For my 01 truck, I believe I only had to remove the A/C Recirculation wire in the PCM and replace with the low or high speed trigger for the fans themselves and not any from the A/C Pressure sensor. The BP A kit instructed to add the 3 wires into spots that weren't being used on my truck.
I don't think the instructions for the BP Automotive kit have been posted here, but here they are. For my 01 truck, I believe I only had to remove the A/C Recirculation wire in the PCM and replace with the low or high speed trigger for the fans themselves and not any from the A/C Pressure sensor. The BP A kit instructed to add the 3 wires into spots that weren't being used on my truck.
awesome! I should have verified before I put everything back together to make sure those pin slots were empty, I am sure they are, but I always like to make sure in case there is something different about the suburban compared to the trucks!
I think I’ll order sometime next week and then play around with the different pressures to have it kick over either the single fan high speed or go to dual high speed when it’s up to temp. Gotta make sure it’s working good with the front and rear A/C going lol
On my 2001, I had to upgrade the OS to 12212156 from a 2002 truck. Otherwise my fans would come on as soon as I started the truck, but I could manually control them with a tech2, it was a bit annoying to get figured out to say the least. But with that OS the come on with the temp and will turn on low with the A/C, but want to get it to go to high like my 04 does
damn, what is your new PCM out of? Did you make changes in regard to charging using a tuner? I wonder if that is causing your cluster to burn up if it’s configured for a newer truck and not the 99 setup
Got a 411 PCM out of a 2002 Silverado (5.3, 4WD). I also ran into the 4WD issue I've seen others mention before where on some of the first year trucks the 4WD also will not work right if you try to swap in a newer 1MB 411 PCM - 4Hi will work but 4Lo will not engage. Did not expect the cluster issue though. I should have thought of that before since I know there are a few slight differences on the 99 trucks (Escalade cluster has to be modified to work in a 99 or the airbag light will stay on for example - I have some instructions to do that mod to a 2002 Escalade cluster by the way). I have a full EFILive (with a software bug that lets me do calibration only flashes without licensing ) but it looks like I'll need to burn a license and probably do a full flash on my original 512k PCM. That being said, I need to see what OS my original PCM is running. The fans do not immediately come on with it but they will once it gets up to temp.
Got a 411 PCM out of a 2002 Silverado (5.3, 4WD). I also ran into the 4WD issue I've seen others mention before where on some of the first year trucks the 4WD also will not work right if you try to swap in a newer 1MB 411 PCM - 4Hi will work but 4Lo will not engage. Did not expect the cluster issue though. I should have thought of that before since I know there are a few slight differences on the 99 trucks (Escalade cluster has to be modified to work in a 99 or the airbag light will stay on for example - I have some instructions to do that mod to a 2002 Escalade cluster by the way). I have a full EFILive (with a software bug that lets me do calibration only flashes without licensing ) but it looks like I'll need to burn a license and probably do a full flash on my original 512k PCM. That being said, I need to see what OS my original PCM is running. The fans do not immediately come on with it but they will once it gets up to temp.
1. They Did not make a 1MB 411 PCM
2. Are you sure its a bug? Sounds like a partialy hacked version. Unless you already licensed the PCM.
Ah - right I was thinking of another PCM that is 1mb....
Oh yes, quite sure. I posted it about it on the EFI forums after I got it. I was new to it and was curious on the licensing since I could do a calibration flash. A few replied then someone from EFILive deleted the tread and sent me a message.
"Thank you for your post. Recently we corrected the bug that you've posted today. You will be asked to license your ECM during cal flash after our next software update."
For me that was saying, do not ever update your software or device. lol
For what its worth - it works fine on any LS1B type controller I have tried so far (about a dozen) but not for a full flash. Calibration only though. Tried it on a 99 Blazer I have and it does not work on that L31 controller. Had to license that one... Also of course, I am missing out on any future bug fixes, new software features, etc.
Went to the junkyard this weekend and was able to get a 145amp alternator and the wiring for the pressure sensor from a 2006 Yukon Denali for $50. Got the new pressure sensor in the mail today and have everything installed and wired up and running good. I configured my pressure settings to be similar of my 04 2500hd and for me, I was able to use either analog or serial cycling and have the same results so I left it on serial cycling for now. But fans kick on and off with pressure and kick on my high fans like 05+ trucks! Could not be happier and well worth the time!
08-05-2020, 06:47 PM
) but it looks like I'll need to burn a license and probably do a full flash on my original 512k PCM. That being said, I need to see what OS my original PCM is running. The fans do not immediately come on with it but they will once it gets up to temp.
