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Old 01-19-2016, 06:33 PM   #1
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Change cooling fan temperature switch points

I see a lot of discussion about managing engine temperatures. To me it seems that many issues would be resolved if the fans would just kick in a little earlier. 160 degree thermostats is no help in stop and go traffic if the fans kick in at the same high temperature.
Has anyone tried to change the fan switch points in the engine controller - DME?
Seems like this should be no more difficult than changing the redline rmp etc.
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Old 01-24-2016, 04:46 AM   #2
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I have asked the same here before without success. I guess the solution is to re- program the computer. Noticed that with AC on, engine temp is generally lower when driving at lower speed due to the fans in low speed. Not perfect but helps a bit.
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Old 01-24-2016, 06:36 AM   #3
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I think a better way would be to have a manual switch to activate the fan.

Take a look at post number two by Qmulus in the below thread. I have considering doing this numerous times..... if I could only identify where to "In a convenient place cut the yellow/gray wire from DME to the high speed fan relays".

Manual radiator fan
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Old 01-24-2016, 06:53 AM   #4
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What issues?

Solutions looking for problems seems to me.
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Old 01-24-2016, 10:02 AM   #5
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What issues? Solutions looking for problems seems to me.
The perceived issue is that the ECU allows the temp to get too high before turning on the radiator fans. Heat is the enemy. Higher temps = reduced oil performance = greater engine wear = shorter engine life. At least that is the theory and concern. As the OP stated, he would like to be able to change the temp setting or have a way to manually engage the fans at a lower temp.

To the best of my knowledge, the temp settings can't be reprogrammed in the ECU. Thus, others have installed a manual switch.

I am testing out a manual switch for the engine bay fan (passenger side rear fender) this afternoon and if it works, I'll post up the details for that one.
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Old 01-24-2016, 10:10 AM   #6
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I have considering doing this numerous times..... if I could only identify where to "In a convenient place cut the yellow/gray wire from DME to the high speed fan relays".
I would do this under the dash where the relays are located. Just find the trigger wire going to the relay and then back up and find a good place in the wire harness to splice in.
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Old 01-24-2016, 10:28 AM   #7
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Nice mod......really want this for dealing with being stuck in traffic .....I imagine having having the fans running while moving at speed would improve cooling air flow as well.

Anybody have a idea which stock switch might give a SPST configuration? Maybe wiring diagrams show this. It would be nice to package this switch in the batwing andlook stock.....maybe a repurposed seat heater switch
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Old 01-24-2016, 11:17 AM   #8
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Jay - the OEM switches are all momentary, meaning only active while being pressed. You'd have to hold it.
That, or get a bit more complex with the setup.
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Old 01-24-2016, 11:28 AM   #9
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Jay - the OEM switches are all momentary, meaning only active while being pressed. You'd have to hold it.
That, or get a bit more complex with the setup.
Ugh....a latching relay set-up. I guess I am going to end up with a row of toggles.......which I quite like. Un fortunately they don't fit well with the style of the interior.
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Old 01-24-2016, 06:57 PM   #10
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Originally Posted by jaykay View Post
Ugh....a latching relay set-up. I guess I am going to end up with a row of toggles.......which I quite like. Un fortunately they don't fit well with the style of the interior.
Or, you can use a step relay.
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Old 01-24-2016, 07:02 PM   #11
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Quote:
Originally Posted by Chuck W. View Post
I think a better way would be to have a manual switch to activate the fan.

Take a look at post number two by Qmulus in the below thread. I have considering doing this numerous times..... if I could only identify where to "In a convenient place cut the yellow/gray wire from DME to the high speed fan relays".

Manual radiator fan
If you are looking for more "fan power" why not jumper the low speed relay wires with the high speed relay? in that case, the fans will always kick in on high.
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Old 01-24-2016, 08:44 PM   #12
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Has anyone considered the OBDII connector and sending the right signal to the computer.

The Durametric units can turn the fans on and off and set the fan speed. Perhaps this is another OBDII Arduino Hack candidate.
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Old 01-25-2016, 03:33 PM   #13
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just turn your ac on . thats what i do in the heat and traffic .
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