Last night during a tuning session I thought maybe that my unused EGR
solenoid output could be used for controlling an electric fan through a relay.
Has anyone tried this? It seems that it would be feasible. Currently I am using a "probe" type mechanical dumb thermostat. I hate the way it controls the fan. I believe that the duty cycle would have to be 100% because the relay wouldn't want to see a pwm type signal. The EGR min temp on could be used, what could be used to shut it off? Or If the temp was set right it would shut off when the fan cooled itself below the set temp? Any ideas would be appreciated.
Randy

 

Did I ask a stupid question? TTT

 

No, not really. It is just that every several months or so someone asks this same question. But they don't seem to want to try it and post back what they found. From what I can tell of how the '747 EGR works, you may be able to use it for a fan. Although there may be some side affects.

Most of the settings can or need to be set to minimum or maximum values. Set $1B3 to the fan on/off temperature. Note there is no upper/lower threshold for CTS.

Set the MPH thresholds to 0 ($1B4 & $1B5)
Set the TPS thresholds to 0 ($1B6 & $1B7)
Set the vacuum thresholds to 254, 1KPa ($1B8, $1B9, & $1BE)
Set the filters to 255, 100% ($1BA, $1BB, $1BC)

Set the DC% threshold to 0, that should turn on the fan immediately ($1BD).
Maybe set the TPS high off at some level so that the fan goes off under load ($1BF)

Then set the EGR tables so that the SA & fueling doesn't change when the EGR/fan goes active/inactive.

Let us know how you make out with it.

RBob.

 

Rbob,
Thank you for the explanation. I will try it tomorrow AM. I will be sure to follow up with my findings. The searches I made did not find any results no matter how I varied the search terms.....oh well. I am not a fan of redundant questions myself and can understand the frustration.
Thanks. Randy