Cooling fan wiring and operation - Miata Turbo Forum - Boost cars, acquire cats.

Welcome to Miataturbo.net   Members
 


ECUs and Tuning Discuss Engine Management, Tuning, & Programming

Reply
 
 
 
LinkBack Thread Tools Search this Thread
Old 07-29-2011, 07:24 PM   #1
Free Moustache Rides
Thread Starter
iTrader: (8)
 
matthewdesigns's Avatar
 
Join Date: Jun 2008
Location: Colorado Springs
Posts: 1,656
Total Cats: 49
Default Cooling fan wiring and operation

About the only sensor left under the hood that's on the stock Miata harness now is the cooling fan thermoswitch. I've been looking into the fan wiring and wondering how I can eliminate the harness altogether to clean up under the hood. My understanding, based on the '92 wiring schematic, is that the thermoswitch grounds the switching side of the fan relay, closing the power circuit so that the fan turns on. Is this correct? I also see that there is a connection on the same lead to the ECU at pin 1R and the diagnostic connection, but I can't decipher how they interact with the relay switching.

Simply put: Can I just run a new lead from the relay to the thermoswitch and expect the fan to function normally? I'd like it to remain fused in the stock fusebox, and best I can tell this would accommodate that setup if it would work.

How do you guys with MS wire it up? My ecu does not have native control over the fan, and there's no input available that can reference a temp input, so I can't just program it internally to switch a ground.

Last edited by matthewdesigns; 07-29-2011 at 07:34 PM.
matthewdesigns is offline   Reply With Quote
Old 07-29-2011, 10:27 PM   #2
y8s
2 Props,3 Dildos,& 1 Cat
iTrader: (8)
 
y8s's Avatar
 
Join Date: Jun 2005
Location: Fake Virginia
Posts: 19,038
Total Cats: 407
Default

with the ms3x i wire the NB fans independently to come on at different temps. the condenser fan also comes on with the a/c
y8s is offline   Reply With Quote
Old 07-30-2011, 02:27 AM   #3
Senior Member
iTrader: (4)
 
Join Date: Jan 2008
Location: Falls Church, VA
Posts: 1,367
Total Cats: 16
Default

Quote:
Originally Posted by matthewdesigns View Post
My understanding, based on the '92 wiring schematic, is that the thermoswitch grounds the switching side of the fan relay, closing the power circuit so that the fan turns on. Is this correct?
Yes.

Quote:
Originally Posted by matthewdesigns View Post
I also see that there is a connection on the same lead to the ECU at pin 1R and the diagnostic connection, but I can't decipher how they interact with the relay switching.
It's ground switched and those are just alternative means to ground it. In the diagnostic box if you jumper TFA and GND, the fan will (should) turn on. You would do this to test if you possibly had a bad fan relay or a bad thermoswitch and wanted to verify that the fan itself still works.

Quote:
Originally Posted by matthewdesigns View Post
Simply put: Can I just run a new lead from the relay to the thermoswitch and expect the fan to function normally? I'd like it to remain fused in the stock fusebox, and best I can tell this would accommodate that setup if it would work.
Yep. Just wire the thermoswitch in line between the relay and ground. Switch is normally open and will close at 207* to turn on the fan, and open to turn it off at 194*.

Quote:
Originally Posted by matthewdesigns View Post
How do you guys with MS wire it up? My ecu does not have native control over the fan, and there's no input available that can reference a temp input, so I can't just program it internally to switch a ground.
We basically do exactly what you've just said your neanderthal ECU can't do.
ScottFW is offline   Reply With Quote
Old 07-30-2011, 01:42 PM   #4
Free Moustache Rides
Thread Starter
iTrader: (8)
 
matthewdesigns's Avatar
 
Join Date: Jun 2008
Location: Colorado Springs
Posts: 1,656
Total Cats: 49
Default

Great, thanks! And yeah, the next gen DSM ecu switched the fans (walking upright as it were lol) but I'm stuck with an external trigger. I've got the ability to monitor/switch based on other parameters, just nothing temp based.

And hmm, I thought the switch closed at 195...no wonder I can't keep temps below 206-210 when I'm beating on it. Will now look for lower temp switch.
matthewdesigns is offline   Reply With Quote
Old 07-30-2011, 02:10 PM   #5
Boost Czar
iTrader: (61)
 
Braineack's Avatar
 
Join Date: May 2005
Location: Chantilly, VA
Posts: 72,899
Total Cats: 1,792
Default

(zack morris's phone)

Summit sells a switch like you are looking for based on temps
Braineack is offline   Reply With Quote
Old 07-30-2011, 06:10 PM   #6
Free Moustache Rides
Thread Starter
iTrader: (8)
 
matthewdesigns's Avatar
 
Join Date: Jun 2008
Location: Colorado Springs
Posts: 1,656
Total Cats: 49
Default

Thanks Brain. I knew I had seen one but I could not remember where.
matthewdesigns is offline   Reply With Quote
 
 
Reply

Related Topics
Thread Thread Starter Forum Replies Last Post
My solution for Oiltemp and Oilpressure input into Megasuirt (MS3) Zaphod MEGAsquirt 41 01-24-2016 01:25 PM
Expected intake temps on the track? tazswing Race Prep 20 10-03-2015 12:04 PM
Are my coils failing? viriiguy General Miata Chat 5 09-28-2015 08:39 PM
wiring wideband ground to battery terminal btabor ECUs and Tuning 10 09-28-2015 06:33 PM


Thread Tools Search this Thread
Search this Thread:

Advanced Search

Posting Rules
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is Off
Trackbacks are Off
Pingbacks are Off
Refbacks are Off



All times are GMT -4. The time now is 02:28 AM.