HOW TO DO AN ADVANCED SEARCH.
Mon Jul 08, 2013 3:56 pm by Admin
For the benefit of 944Hybrids users there are two search functions available for you to use.
The purpose of this sticky is to explain the "Advanced Search" function because it is much more powerful and is the best choice when researching information.
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3 relay cooling fan wiring - - - > question
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hutchjc1
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944Hybrids: 924/944/968 and 928 V8 Conversions :: Technical Stuff (other than motors) :: Electrical Mods
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Re: 3 relay cooling fan wiring - - - > question
No problems so far. I put a few hundred miles on it without any issues with the cooling system.
Arthropraxis- Posts : 1103
Join date : 2009-09-02
Re: 3 relay cooling fan wiring - - - > question
Arthropraxis wrote:I took the high and low speed Porsche relay wires from the thermofan switch at the radiator. The thermofan switch won't be used so I cut the connector off and pulled the wires back through the harness covering on that side, routed them over to the passenger side and soldered them to the respective GM high/low speed fan relay wires.
Awesome. Looks like I will be doing the same here soon.
So, what are you guys running for temp settings?
robstah- Posts : 352
Join date : 2009-08-28
Age : 38
Location : Athens, GA
Re: 3 relay cooling fan wiring - - - > question
Arthropraxis wrote:No problems so far. I put a few hundred miles on it without any issues with the cooling system.
cool thanks for the reply, im going to wire mine like this today!
-B
B.Rudy- Posts : 40
Join date : 2009-08-21
Location : Raleigh, NC.
Re: 3 relay cooling fan wiring - - - > question
I think these are my fan settings with a factory turbo radiator and fans using a stock 180 degree thermostat. I should have written it down.
Fan 1 on: 195
Fan 1 off: 190
Fan 2 on: 205
Fan 2 off: 195
Fan 1 on: 195
Fan 1 off: 190
Fan 2 on: 205
Fan 2 off: 195
Arthropraxis- Posts : 1103
Join date : 2009-09-02
Re: 3 relay cooling fan wiring - - - > question
So if you use the harness from the Porsche temp sensor does it matter which of the 2 wires connect to the 2 wires from the pcm ? I expect to use pin 42 out of C1 for low speed and pin 32 out of C2 for high speed.
Thanks !
Thanks !
hutchjc1- Posts : 68
Join date : 2015-07-21
Location : Westminster Maryland
Re: 3 relay cooling fan wiring - - - > question
Yes, one of the wires is low and the other is high speed and they connect to the respective wires on the LS1 PCM.hutchjc1 wrote:So if you use the harness from the Porsche temp sensor does it matter which of the 2 wires connect to the 2 wires from the pcm ? I expect to use pin 42 out of C1 for low speed and pin 32 out of C2 for high speed.
Thanks !
I noticed my last post in this thread was in 2012. That means I have been daily driving this car for 4 years. No issues with the temperature in the high heat and humidity of the southeast.
Arthropraxis- Posts : 1103
Join date : 2009-09-02
Re: 3 relay cooling fan wiring - - - > question
Admin wrote:Are you using the factory fans?
If so, why are you going through all the trouble of rewiring them. All you have to do is hook up two simple wires from the PCM to the factory 2 speed relay and your done. NO wire size to worry about , NO wiring diagram to worry about , NO finding fuses and hiding everything to look right.
-------------
I'm thinking of trying this method vs. the 3 relays- do I understand correctly that I wire the high/low control from the PCM into the Porsche fan relay? Any tips on which wires, and the easiest way to do that?
Assuming I would wire into the relay box where the thermoswitch used to connect to the relay?
Thanks-
Jasonscottw- Posts : 125
Join date : 2013-10-17
Re: 3 relay cooling fan wiring - - - > question
Sorry to necro bump this thread, but can you (or anyone else) elaborate on this?
I assume there is a low speed input and a high speed input from the PCM to the relay?
Are you using the factory fans?
If so, why are you going through all the trouble of rewiring them. All you have to do is hook up two simple wires from the PCM to the factory 2 speed relay and your done. NO wire size to worry about , NO wiring diagram to worry about , NO finding fuses and hiding everything to look right.
I assume there is a low speed input and a high speed input from the PCM to the relay?
87944turbo- Posts : 76
Join date : 2017-04-28
RE: Wiring
Yes
C1-42 is the “LOW” fan output to the relay bank
C2-33 is the “HI” fan output to the relay bank
At least for my harness, that is. I emulated my harness as a 2002 Corvette
C1-42 is the “LOW” fan output to the relay bank
C2-33 is the “HI” fan output to the relay bank
At least for my harness, that is. I emulated my harness as a 2002 Corvette
Punisher948- Posts : 39
Join date : 2012-07-19
Age : 56
Location : Flint, MI
Re: 3 relay cooling fan wiring - - - > question
Yes
C1-42 is the “LOW” fan output to the relay bank
C2-33 is the “HI” fan output to the relay bank
At least for my harness, that is. I emulated my harness as a 2002 Corvette
Excellent, thanks!!
87944turbo- Posts : 76
Join date : 2017-04-28
Re: 3 relay cooling fan wiring - - - > question
So I wanted to follow up on this. I have been having this issue since I went with the 3 relay setup. I believe I have everything wired correctly, but my symptoms are this. My fans kick on at low speed at the expected temperature (verified through a temperature gauge). Fans step up to high speed at the the expected temperature.
However, once the fans reach high speed, they don't kick back down. Also, the temp will remain steady around 190F. I am using a 160 thermostat.
I have the stock radiator in now, but going to put in a higher capacity radiator this winter. Just trying to sort this out before it gets warm out. Planning on tracking it in a few months.
However, once the fans reach high speed, they don't kick back down. Also, the temp will remain steady around 190F. I am using a 160 thermostat.
I have the stock radiator in now, but going to put in a higher capacity radiator this winter. Just trying to sort this out before it gets warm out. Planning on tracking it in a few months.
87944turbo- Posts : 76
Join date : 2017-04-28
Re: 3 relay cooling fan wiring - - - > question
Ive ran the three relay setup since i put the motor in the car about 10 years ago (time flies!!) And i havent had any issues with the computer controlling the fans. I have a bigger radiator than stock though.
spence- Posts : 684
Join date : 2009-07-21
Age : 41
Location : St.Catharines, Ontario, Canada
Re: 3 relay cooling fan wiring - - - > question
Hey Spence, thanks for the reply. Just curious what temp t-stat are you using, and fan set points?
These are my fan settings. Maybe they're just too low?
These are my fan settings. Maybe they're just too low?
87944turbo- Posts : 76
Join date : 2017-04-28
Re: 3 relay cooling fan wiring - - - > question
Mine is a 160 too. I think i lowered the fan set points some, i cant remember what the limits where though.
spence- Posts : 684
Join date : 2009-07-21
Age : 41
Location : St.Catharines, Ontario, Canada
Re: 3 relay cooling fan wiring - - - > question
87944turbo wrote:So I wanted to follow up on this. I have been having this issue since I went with the 3 relay setup. I believe I have everything wired correctly, but my symptoms are this. My fans kick on at low speed at the expected temperature (verified through a temperature gauge). Fans step up to high speed at the the expected temperature.
However, once the fans reach high speed, they don't kick back down. Also, the temp will remain steady around 190F. I am using a 160 thermostat.
I have the stock radiator in now, but going to put in a higher capacity radiator this winter. Just trying to sort this out before it gets warm out. Planning on tracking it in a few months.
The stock radiator is probably whats keeping your temps high. It doesn't have enough cooling capacity for the LS. I run 180 thermostats in almost all of my builds. These engines will run more efficient at a higher temp. With a 180 Tstat and the bigger radiator, fans will cycle on and off as needed.
Hotrodz of Dallas- Posts : 615
Join date : 2015-10-31
Age : 65
Location : Dallas-Ft. Worth
Re: 3 relay cooling fan wiring - - - > question
The stock radiator is probably whats keeping your temps high. It doesn't have enough cooling capacity for the LS. I run 180 thermostats in almost all of my builds. These engines will run more efficient at a higher temp. With a 180 Tstat and the bigger radiator, fans will cycle on and off as needed.
Good to know, thank you for that. One thing I have had trouble finding is what temperature is too hot. I would think over 210 is pushing it? I was hoping that I would be able to push the temps down a bit to give myself some additional "head room", particularly on track.
I have a larger capacity radiator that I will be putting in this winter. Will plan on putting in the 180 t-stat and adjusting accordingly at that time.
87944turbo- Posts : 76
Join date : 2017-04-28
Re: 3 relay cooling fan wiring - - - > question
Our own racecar has a 180 in it and runs between 180-190 on the track. If we use a 160, it runs closer to 200. The 160 stays open too long and water flows thru the radiator too fast to give it a chance to remove heat from the coolant. I know it sounds odd, but that was explained to me by a major performance radiator manufacturer a few years ago.
Hotrodz of Dallas- Posts : 615
Join date : 2015-10-31
Age : 65
Location : Dallas-Ft. Worth
Re: 3 relay cooling fan wiring - - - > question
Our own racecar has a 180 in it and runs between 180-190 on the track. If we use a 160, it runs closer to 200. The 160 stays open too long and water flows thru the radiator too fast to give it a chance to remove heat from the coolant. I know it sounds odd, but that was explained to me by a major performance radiator manufacturer a few years ago.
That's really interesting. That's a thought that has been running through my head for a while.
87944turbo- Posts : 76
Join date : 2017-04-28
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944Hybrids: 924/944/968 and 928 V8 Conversions :: Technical Stuff (other than motors) :: Electrical Mods
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