1999 Silverado LQ4 Efan conversion. Low speed fans always on.

[IvanDeslayer]

Morning ya'll,
Haven't been able to play much with my Hptuner for actually tuning but was able to use it to enable an efan conversion. I used parts off a 2005 Silverado to get a stock 3 relay fan setup. I'm using pin 33 and 42 and I thought I enabled everything correctly. I can manually go in and turn on the low speed fans and the low speed fans come on and I can do the same to the high speed fans. My problem, I found over the weekend, though is the low speed fans are on constantly after starting the truck and not KOEO. I can, with the scan tool, turn them off but once I back out they are back on. Attached is the tune I used. I'm probably missing something obvious but I'm not seeing it can someone take a peek at it?
Thank you

[IvanDeslayer]

No one?
Anywho, doing a little more research I stumbled on some facts but IDK if this is part of my issue. 99-02 Silverados do not have a pressure sensor sending the VCM information but instead have a couple of pressure switches feeding the PCM information controlling the A/C. Reading through a couple of threads it says to copy over the settings from a 05 Corvette or similar to enable the fans. IDK if this is applicable to my situation or not since these other vehicles have and actual pressure sensor rather than a switch. Does Anyone know if you need to wire in a pressure sensor for this to operate correctly or should I change up the settings.
Thanks Again,
Walt

[mecanicman]

Been awhile since I played with it but I think your O/S is the issue. From what I remember the older ones don't control the fans properly, I had to switch to newer. The fan then functions correctly with no changes to wiring.

[tek1229]

Hey Walt, no experience with this but try using the tech 2 and see if there is a parameter for a/c pressure? It sure looks like these tables are looking for pressure input.. Real curious if there is a reading and what that reading is.. Might have to enter a newer vehicle into tech2 or tech2win to see if the parameter shows up..

To see if it's the a/c pressure turning on the low speed fans you could change the enable/disable pressures to max limits..

Poor mans trick is I might try is changing the fan 1 enable AC pressures to max, whatever that is.. 800psi or something and seeing if the fans no longer come on.. Then change the fan 1 ON temp AC ON to something like 80 degrees so whenever the a/c is turned on the fans turn on.. If low isn't enough to keep your a/c pressure in check then change fan 2 on AC ON settings the same..

[tek1229]

Oh ya, you might have to turn on the codes for the cooling fan and a/c pressure control circuits.. Don't need to have then turn on the mil on 2nd time but enable them and change them from no error reported to no mil..

P0480 and p0481
p0530 and p0531

[IvanDeslayer]

Been awhile since I played with it but I think your O/S is the issue. From what I remember the older ones don't control the fans properly, I had to switch to newer. The fan then functions correctly with no changes to wiring.

Thank you for the response,
After some more Google Foo I was starting to come across a couple of threads saying that. If that's it do I just take a stock O/S for an 02 LQ4 write my VIN and set the fan parameters again? I guess the stupid question is where do I find a stock O/S for and LQ4?

[mecanicman]

The tune repository, go to hpt home page and log in.

[radz28]

Unless I was missing something, and that very well could be the case, I'v found that the low and high-speed fans always run, just after start-up with my e'fan conversion. I used an OEM-type fan assembly from Autozone with Nelson's relay harness, and quadruple-checked EVERYTHING, including several OEM-fan tunes, and can't get them to not run at idle. They will turn off at whatever speeds I've programmed, but they will always run below those speeds. I believe that's just the way the PCM runs them. I do not believe we have the discrete functions of later PCMs, so I gave up. At least I won't overheat in traffic, LOL!!!

[IvanDeslayer]

The tune repository, go to hpt home page and log in.

Sorry for the later reply and NOOB question. So I've found a OS I can use. Do I need to spend the credits to lay the new OS into my PCM? I guess I'm confused as to how I'm going to replace the OS system. I understand I'll need to do a full write and afterward change what I've already changed i.e. tire size and such but how do I initiate the process.

Thanks for the help,
Walt

[IvanDeslayer]

Oh ya, you might have to turn on the codes for the cooling fan and a/c pressure control circuits.. Don't need to have then turn on the mil on 2nd time but enable them and change them from no error reported to no mil..

P0480 and p0481
p0530 and p0531

Thanks Tom,
I did try that and it didn't change anything. My mindset is I've gone to the trouble of changing over to efans I'd like them to work properly. It doesn't do any good if the fans are still on even over 35 mph. I could have just stayed with the clutch fan.

[tek1229]

Thanks Tom,
I did try that and it didn't change anything. My mindset is I've gone to the trouble of changing over to efans I'd like them to work properly. It doesn't do any good if the fans are still on even over 35 mph. I could have just stayed with the clutch fan.

Thanks for trying.. What I was hoping is that it is turning on by default because the pressure switch is missing.. I was just wondering if that could have worked to verify they were coming on because of incorrect/bad pressure readings..

I don't have your tune in front of me, but isn't there an off/mph chart that would turn off the fans once your up to speed?

[Alvin]

The problem is the 99-02 Silverados do not have a A/C pressure sensor so it cannot come on via high side pressure like the newer trucks. We have a harness we sell with a special circuit built in that gives normal high/low operation like the late trucks with a A/C boost. Here is a little matrix to show how it works to save me from typing it all out


fan controls 99-02.png

[IvanDeslayer]

The problem is the 99-02 Silverados do not have a A/C pressure sensor so it cannot come on via high side pressure like the newer trucks. We have a harness we sell with a special circuit built in that gives normal high/low operation like the late trucks with a A/C boost. Here is a little matrix to show how it works to save me from typing it all out


fan controls 99-02.png

Morning Alvin,
Thanks for the reply. Yeah after much searching and going through multiple topics all through Google Foo I've found that part of my issues will be bringing secondary fans online because there is no live read pressure to the VCM. How does your harness go about solving my first problem, fans constantly on? Does your special circuit harness add the pressure sensor or does it read something else to engage the high speed fans? Is the harness on your website? With your harness do I still use the current setting I have, (see original post with tune) will I continue to use pins 42 and 33?
Thanks again,
Walt

[Alvin]

Hi Walt, Did you see the image I posted? That is the way it will work. It will use red33 and blue 42 for high and low and it uses the AC clutch to add or subtract from the HI/LOW setting. Its really all pretty slick and works like OEM.

http://www.pcmofnc.com/index.php/per...conversion-kit

[IvanDeslayer]

Hi Walt, Did you see the image I posted? That is the way it will work. It will use red33 and blue 42 for high and low and it uses the AC clutch to add or subtract from the HI/LOW setting. Its really all pretty slick and works like OEM.

Yup, did look at the image I was just confused where it was drawing the temp data. Looks as though you built the logic into the harness. Cool deal. Actually at this point I would just need your logic circuit and not the entire harness.

[IvanDeslayer]

Thank you for the response,
After some more Google Foo I was starting to come across a couple of threads saying that. If that's it do I just take a stock O/S for an 02 LQ4 write my VIN and set the fan parameters again? I guess the stupid question is where do I find a stock O/S for and LQ4?

Sorry for the late reply and Necromancing the thread BUT if I'm going to use a 02+ OS for my truck and still keep the stock calibration do I write the entire 02 OS with my tables or do I write the 02 OS and the write my 99 calibration to it. I think I know the answer but can someone confirm?

[MiniTubbedNova]

I looked at your tune. Its fan on 226, Which is high i would think, The low is also high at 219. I would lower those temps some. also you have a min time on as 90 seconds. which means if the fan turn on it will run for at least 90 seconds. you could lower that, it will give you a quicker look to see what is turning on and off the fan. Run a scan and see if your temps drop below the temp. if they do something else is keeping the fan on. if you can run a scan and post that with your newest tune.

[IvanDeslayer]

Thanks, I'll try that.

[CoolByAccident]

Have you had any luck with your issue?
I recently swapped in a 2002 5.3 with a 2001 harness/ecm into a 1991 c1500.

I'm using some Ford Windstar fans and my low fan stays on at startup regardless of coolant temp.

[Turbo Junky]

Super old thread getting dragged up here but I need some help....

Just installed efans on a 1999 Sierra and I can't get the fans to turn off regardless of engine temp or ac settings. I have tried a number of different things with no luck. I am currently using pin 42 for fan 1 control and I wired a relay to the AC clutch signal for the second fan since pin 33 was in use.

Any help would be greatly appreciated, thanks!