e fan wiring and control

[kostelacd69]

ive got a 01 silverado 5.3 with cos3. trying to get pin 42 to controll my fans but it just stays on. i can go into the scan tool and turn them on and off and nothing happens. not useing fan #2 just one any ideas

[kostelacd69]

this is my tune that both 42 and 33 stay grounded untill you shut the truck off anybody

[chevy052500hd]

did ya try a full flash after changing? Maybe the settings didn't take. Only thing I could think of is a wiring issue with the relays, pcm looks ok as far as programming. Pin 42 on blue connector is your fan #1, but probably stating stuff you already know.

[kostelacd69]

what do you mean by full flash all i ever do is hit the red arrow in the center. the wires are staying grounded hooked up to relays or not thats why in confused.

[chevy052500hd]

okay full flash is the red arrow all the way to the right. you have the green read arrow center red calibration flash and then the right full flash red arrow.

The pcm will ground the relays so pin 85 on the relay should go to the pcm and pin 86 go to 12v power. That is the coil terminals in the relay. terminals 30 and 87 on the relay are the contacts.

[kostelacd69]

yeah i know how the relays are set up but my thing is the ground coming out of the pcm is staying grounded and never turns off untill 5 sec after you shut the truck off i put my old tune back in it and it stays grounded on that one as well then i went into the scan tool and tried to turn the fans on and off that way and it gave me a unable to connect box so i tried the ac compressor on off and that worked so wtf am i doing worg i only need control of fan 1 not 1 and 2 but ive tried both ways and the same thing every time is there another pin i should use or just 42 and 33 cause neither of them change from being grounded

[chevy052500hd]

try maxing out G0903

I also noticed on a/c pressures for fan 2 were not matching with fan1 try matching the two 3447 kpa see if that helps

[chevy052500hd]

only other thing is try a full flash and see if that fixes it otherwise may possibly be a pcm issue.

[kostelacd69]

ok i got it my meter was lieing to me so after adjust the parameters and hooking it all back up it works thanks for all your help

[chevy052500hd]

cool :cheers: