Efan activation

[04BlueSS]

I have a 2004 silverado ss that has a mechanical fan. I am trying to install 05 silverado electric fans but cannot get the trigger from the ecm to activate. I am using the empty connection for pin #42 on my ecm and the pin is fully seated, but for the life of me I cannot get my computer to activate this. Here is what my settings are, hopefully I am just missing something obvious.
:cry:




Thanks,
Nick

[Blacky]

Have you read through this thread?
http://www.efilive.com/forum/viewtopic.php?t=1433

Regards
Paul

[04BlueSS]

Have you read through this thread?
http://www.efilive.com/forum/viewtopic.php?t=1433

Regards
Paul

Yes I have read that, but from what I understand are trucks use pin #42 for fan #1 output. I am not trying to have a high and low feature although that would be nice. Here is the thread that I was using for my info, sorry its kind of long. http://www.silveradoss.com/forums/in...showtopic=9616

I pm'd another user on the SilveradoSS board that posted in that thread to confirm if that was indeed the correct pin#, and they use the exact one I am. The only difference is they are having there pcm's programed by a third party (pcm4less I believe). I didn't know if Flashscan was configured to use that pin for fan activation or not. Should I try it in pin #33? Is that pin open or does it control the ac recirculation door as stated?

Thanks
Nick

[GMPX]

Hi Nick,

I am sure the Aux Fan Output comes from connector Blue#42.
This is also Fan #1.
Red #33 does the double up as the A/C recirc output and Fan #2.
There is a few thresholds I would change in your settings.
These are just guesstimate settings.
G0904 = 60MPH
G0905 = 50MPH
This tells the PCM to turn the fan off at 60MPH and re-enable if needed at 50MPH.
As it was, the PCM read it as, turn the fan off at 0MPH, and back on at 0MPH
The turn on/off delays are O.K at 0.
Minimum On-Time would be best changed to say 30secs to stop the Fan cyling on/off every 2 or 3 seconds.
Fan#1 & #2 both off, set that to about 70MPH or so.

Try that and see how you go.

Cheers,
Ross

[04BlueSS]

Ross,

I changed all the values you suggested and did a reflash. Went for a drive to get coolant temp into fan operating range. Parked left truck running and tested trigger wire, still not getting a 12v signal, only 105 -85mv reading. Ect's were at 198F while testing.

Shut off, pulled connector from pcm to verify, pin still seated, #42 connector hole, thought maybe could be a break in the wire, so I did a ohm test on connector side to trigger end of wire got .1-.2 ohms of resistance so I am stumped.

Thanks,
Nick

[GMPX]

Ross,
still not getting a 12v signal, only 105 -85mv reading. Ect's were at 198F while testing.

Nick,

The PCM grounds that output, it does not supply 12V.
One side of the relay should go to either +12V IGN or +12V Batt (Check the wiring diagram), the PCM supplies the Ground to turn the relay on.

Cheers,
Ross

[wait4me]

for a standard 5 pin relay, you hook up pin 30 to power 12v. pin 87 to fan positive wire, pin 85 to positive 12v source, and 86 to the pin on the pcm.. 87a is left blank.

[04BlueSS]

Ross,
still not getting a 12v signal, only 105 -85mv reading. Ect's were at 198F while testing.

Nick,

The PCM grounds that output, it does not supply 12V.
One side of the relay should go to either +12V IGN or +12V Batt (Check the wiring diagram), the PCM supplies the Ground to turn the relay on.

Cheers,
Ross

Thanks for the info, I assumed it was a positive trigger for the relay, I wasn't aware it grounded it. I am glad it is something simple on my end thanks again. Thanks wait4me for the info on how to wire the relay as well.


Nick