I was just curious if it would be possible to turn an unused pin on to control electric fan(s) with the 7747 ECM? If so, can anyone point me in the right direction? TIA

 

Looking at the schematic on that, Pin A2 is an unused output according to the labels.
It could be used to ground a relay coil and turn on the fan.
The fan power would need to come from a fuse and go through the relay contact. the ECM driver can't handle the full current of the fan.
Taking control of it would need to be done in source code by adding a routine to check the temp, turn on the "Port 2" (pin 34 on the processor), adding a check to see when to turn it off (hysterisis so it doesn't cycle on/off too much)and then reassembled.
I don't know the addressing on the 747 but it is possible I think to do what you want.
Someone else may know the actual address on that port to activate it.

 

Ive done the fan control mod with the ECM, but IIRC, you cant get access to the code to make the patch without deleting the onboard ROM. Reason being is that the I/O routines are on the ROM and not the prom. EBL does the fan control, and other things if your looking for additional features for your computer.

 

Jp86ss - I was thinking something along those lines, just a quick turn on at___ turn off at _____ degrees.

Dimented24x7 - who or what is EBL? sorry, still learning on the programming aspect right now.

 

Like Dimented24x7 said,
There's a bit of work to doing the "simple" thing.
Not as easy as a newer ECM (If you can call a P4 newer)
If you need to go into that level of changes anyway, the EBL is the way to go if you can. The hard work has been done for you (and allot more)
If you can't search for "Romless" and go from there. Lots of good info on how its been done.

EBL = The holy grail of TBI control.
Do a quick search and you'll be sure to find it.

 

I have thought about this too with my 7747. What about rewiring the AIR solenoid control to a high amp relay to control the fan. THe temp. settings for the AIR are available. Not sure of the hysterisis built into the AIR routine.

 

I just went thru a bunch of threads and found the website for it.

I think I am in love
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hmmm...I didn't think about that one.

 

hey 75 Wagon that EBL looks rather contagious