Can someone please tell me how I can get the "Disable Fan Speed" setting to ACTUALLY shut off my fan on my 411 PCM????
The temp thresholds are the only way I can control my fan. If I hit the highway after the fan comes on, the fan basically never shuts off and is fighting the airflow through the radiator at highway speeds....
Also, I'm running ONE fan so under "Fan Type" do I want 2 Fans or Aux fans or what???
Bump.
I can't exactly remember what the disable speed is used for, maybe something AC related? Either way, it will not disable the fan like you want it to, or mine doesn't anyway. Just raise your disable ect to where road speed keeps it cool enough. My disable temp is set at 205, and so far it drops below that while cruising. I haven't had this swap done for very long though, so I'm kinda testing still.
2000 K2500 - 489 CI Vortec w/ comp XE270 cam - 0411 swap and rear mount turbo
1972 M35a2
2011 LML Duramax
Thanks for the info. I was hoping that the MPH threshold could simply be used to shut the fan off once you're rolling at a certain speed. Makes me wonder what GM did on their Efans? Did they just set the ECT threshold high enough that even once you're going down the highway with the fan fighting the airflow over the radiator it can just barely get cool enough to shut the fan off using the temp threshold?
The second part of the sentence for disable speed had me hoping that it could be used to turn the fan off at speed.
[ECM] 8033 - First Stage Fan Disable Speed: If AC is on, fan will disable above this speed. If fan is on, it will disable above this speed if coolant is hot (V6 only).
I know it says V6 only there, maybe that's the kicker. But why does the PCM care what it's controlling??
I'm assuming the dropdown box for "Fan Type" is absolutely useless then. 2 Fans or Aux fans.....
What's you enable temp and what Tstat are you running? Details on yours? Mine is a 3 bar SD LQ4 with a 75MM Borg turbo.... Trying to keep the temps as low as possible since the turbo heats everything up.
I have the same ECM and does disable the fans at that disable speed. Are you using one fan or two? Also if you are concerned about underhood temps adjust the Ignition Off Enable Temp from 236 to something lower, I have mine set at 180. I've also increased the run time to 300 seconds. FYI I am using an electric water pump and have wired my water pump to run with the fans as well.
only way I can see to do it without personal experience is disable and enable speeds under fan stage 1
I would personally trial diable speed 55mph enable speed 40mph
A/C fans disable speed 40mph
try selecting 2 fans and set stage 2 enable ECT to max values so it never tries to earth the relay that's not there and see an open circuit.
go for a drive with A/C on and see if it works as desired
just a suggestion never personally done it
DrLoch: Care to share your tune so that I may see your fan settings? Will you please post your tune or at least a screen shot of the fan settings? I sure would appreciate it. I'm using one fan. Also, I have not been able to get the Ignition Off to do anything either...
I'm sure I have some of the setttings whacked here and it's causing me to not be able to disable the fans at speed but I really can't seem to figure this one out.
luke: Yeah I've been playing with those settings but I'm apparently missing something really obvious on this one. I've been running previous tune attempts to get the fans sorted out with the setting of "2 fans". This is the first one where I tried "Aux Fans".... No difference for me.
No A/C on this beast at least for this season.
Hmm guess I was wrong, I would have sworn I read the speed disable didn't work like that. I would also be interested to see your tune DrLoch.
2000 K2500 - 489 CI Vortec w/ comp XE270 cam - 0411 swap and rear mount turbo
1972 M35a2
2011 LML Duramax
This is still a work in progress Imp SS 29 APR 2018 VE OL.hpt
Thanks so much for sharing that DrLoch. I haven't had a chance to test anything yet but when I do I'm going to use your fan settings exactly in hopes that I can finally get the MPH shutoff working that I've been seeking.
After rereading the thread I'm not sure that is going to solve your issue. Post up a log so we can see your ECT. May have to trick it to think that the AC is running and then adjust the A/C Fans Disable Speed to shut down the fan. An other alternative is ti add another relay in series with the existing fan relay that will disable the signal. If you are just trying to see if this will fix an issue a manual switch would work.
What kind of fan is it? does if have a major shroud around it? More information may be helpful.
Wonder how I might trick the PCM to think the AC is on. Currently don't have AC but intend to in the future. I can force the fan on and off with the scanner no problem. I just am trying to get the MPH disable speed setting to shut the fan off at speed.
I'm fairly decent with relays but haven't thought about adding another one in series to accomplish this can you maybe explain in more detail? As far as the manual switch I could just put the fan on a toggle, I'd sure like to keep the PCM controlling the fans though.
I'm not sure what kind of fan it is, it's a aftermarket fan sold by Summit racing that seems to move a bunch of air when it's on. Super scientific I know lol. I have never built or ran a turbo setup before this one so it's definitely been a learning curve for me. My radiator is the 2nd largest OEM big block radiator available for these trucks. 2 or 4 core depending on who I ask about it, not sure myself. In terms of surface area that the fan covers, it could be better, maybe 40% of the radiator surface is covered by the fan and shroud. Even though the fan coverage could be better (and it will be on the next turbo setup I build), once rolling everything stays cool, and once stopped everything settles down into a good cool temperature. The fan doesn't pull the temp down super fast once stopped since the radiator surface coverage could be better, but nonetheless it still will bring the temp down to the point that the fan shuts off. The biggest problem I have is when the fan doesn't go off at speed going down the highway. The air from the fan is fighting the air coming through from driving down the road.
Last edited by CDeeZ; 06-10-2018 at 10:19 PM.
Can you post up a picture? What is the stat temp?
I will get a picture up later. It's a 160*F Tstat. Here's a log sorry I forgot to post one when you mentioned it the first time.
Any movement here? I just started looking into this and realized if my AC is on, my fans are always on regardless of speed.
Unless I'm misunderstanding the speed disable part. Or the AC pressure settings are high enough for them to run.
FWIW you can log fan status to see if they are on or not.
Last edited by scoob8000; 06-18-2018 at 03:13 PM.
Well using the tune settings for the fan shared by DrLoch the fan still won't shut off at a MPH threshold like I hoped. It only shuts off once the temp drops below that threshold. Oh how I wish I could set it up to just simply shut off at 30 MPH or so.
I wonder if anyone has "tricked" the PCM into thinking the AC is on all the time to make the MPH disable work. Perhaps like DrLoch was talking about above? I wonder what would happen if you just grounded the "AC Request Signal" wire to accomplish this?
I believe, the mph for AC only disables them if the temp set points are not met.
It seems like from my testing, if your temp is over the on temp, they are always on regardless of speed.
You may be correct I've never put the correlation together since my temp does fall below threshold. BTW I also have an electric water pump.
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