Ok im trying to get a clear answer on if Pin 33 can be turned on for fan control in the 02 pcm's. I know they can in the 05's but i do not know if it is possible with the 02's. I have not had a clear yes or no. So if someone could tell me that would be great because im trying to figure out if I should by the new 05 fan harness from GM. thanks.
PS I talked to allen and he does not think its possible. however like i said does anyone know for sure.
I think Autozone sells an adjustable water temp sensor that you can use to trigger your fans. Derale has made them for years. Had one on my 92 truck when it had the LT1 engine under the hood.
See my truck data in the "My Garage" section here... http://www.ls1truck.com/forums/my-ga...tml#post191709
Ok i think im going to do the temp sensor and to adjust the fans with the 05 fan harness. a guy on performace trucks did this:
"I bought a adjustable temp controler with a temp sending unit, not the probe that sticks in the radiator.
This is how mine works.
At 168-172*ish the thermostat opens.......
At 175 both fans come on low. The aftermarket controler turns the fans on....
At 189 both fans come on high commanded by the ECM pin 44...
If the A/C is on and the engine is under the low fan turn-on temp the fans come on low....This is the only time the A/C over rides the fans vs. temps.
The stock 05 harness has two wires that goes to the ECM, this are both ground wires that control the relays that power the fans. Sence the aftermarket controler was made to power the fans (not ground a relay like the 05) I just installed another relay that when powered from the aftermarket controler would ground one of the wire that usally goes to the ECM."
Now what is a good temp for the fans to come on high with the pcm. I have a 195 tstat is it like the 05 pcm's extreme hot of like 230? thanks
The PCM commands the low speed cooling fans ON under the following conditions: pin 33
• Engine coolant temperature exceeds approximately 94.5°C (202°F).
• A/C refrigerant pressure exceeds 1447 kPa (210 psi).
• After the vehicle is shut OFF if the engine coolant temperature at key-off is greater than 101°C (214°F) the low speed fans will run for a minimum of 60 seconds After 60 seconds, if the coolant temperature drops below 101°C (214°F) the fans will shut OFF. The fans will automatically shut OFF after 3 min. regardless of coolant temperature.
The PCM commands the high speed fans ON under the following conditions: pin 44
• Engine coolant temperature exceeds approximately 104.25°C (220°F).
• A/C refrigerant pressure exceeds approximately 1824 kPa (265 psi).
• When certain DTCs set.
Posted by hummertech , GM specs !
Now what is a tune again?
Comp Cam 54-412-11 , Int:265, 212, .522 , Exh: 271, 218, .529 , LSA 114 , Longtube , CAI (Vararam) , TransGo HD2 shift kit , tuned by me with EFILive
now is this for the stock 195 stat because if it is ill will put my on temp for my pcm at about 215 so that the fans will stay on low when the a/c comes on and will not kick them on high until that temp. does that sound good. Anyone?
hey redheart, How did derale have his fans turn on? Did he just add another relay say the nelson harness and just have it ground out like the newer pcms do with the 2 pin activation?
I haven't tried the new Derale thermostatic control. I had one in my 92 but it was a totally different design than what they sell now. It had a controller box on the old style unit that supplied power to the fans. There was a sensor you shoved between the radiator cooling fins on the old unit. I don't know what they do now.
See my truck data in the "My Garage" section here... http://www.ls1truck.com/forums/my-ga...tml#post191709
yeah i think they still make them but they have one that is like a pipe thread one. here:
http://store.summitracing.com/partdetail.a...mp;autoview=sku
Do u think that would work. Also could I wire it up similar to the way u did it with the 2 pins? with the controller turning on the fans for low and the a/c and then have the pcm turn on the fans on high if they reached and extreme hot temp.
Can u by that derale contoller at autozone and where would that screw in temp probe go since it is not the one u pust through the radiator.
There are numerous ways that you can trigger the fan relays. The Derale controller is nice because you can adjust it however you want. That controller will trigger two relays if that is what you want it to do. I only see one adjustment for it though. I would have hoped that it was configured with two individual adjusters, that way you would not have to get the PCM reprogrammed to activate the pins inside the PCM. If you go to www.derale.com you will find a few controllers there. They have one with the push-in-between-the-fins sensor if you don't want to figure out where to screw in a 3/8 NPT pipe fitting. I guess if you wanted to, that two individual controllers could be purchased to activate the low speed and one for the high speed relays. I like using the PCM to control the fans but your year model may not allow it. That's definitely a question for Allen. You can put toggle switches on your dash to turn the fans on manually. I have those wired in also so that I can cool the water down as much as possible in stop and go traffic in the heat when the a/c is on, plus it helps the efficiency of the a/c. I have one switch for low-speed fans "on" and another to turn the high-speed fans "on". I supply power to the relays via a switched power lead from the ignition and the dash switches ground the relays as requested.
See my truck data in the "My Garage" section here... http://www.ls1truck.com/forums/my-ga...tml#post191709
well thats the thing i have the pcm programmed for pin 42 to activate the fans. But i wanted something else to turn both the fans on without the fans having to come on high until the pcm turn on temp was reached. Do you think that is possible with this contoller.
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