five7kid

iTrader: (14)

Sorry to ask such a basic question, but a search didn't produce results.

What is the stock (2000 in my case) PCM temp setting for radiator fan on? I understand the 2nd fan doesn't come on until the AC clutch is engaged, and I don't have the AC running yet. I was at the track yesterday, the temp gauge (aftermarket) was showing 220, but I never heard or observed the fan coming on. It may have, the temp didn't get above that, but I was using the heater in an attempt to keep it cool between runs.

cam-

IIRC thats it 220 when it kicks on but you might want to look and see which fan runs as they run a low speed and a high speed fan on LS1's so when the high speed fan turns on the low speed fan turns off. The only time they both run is when AC is on or when you reach danger zone and I think 220 or maybe 240 is it. Its been a while but its something like that.

ghettocruiser

iTrader: (4)

Its been a long time since I looked at my wiring... but for some reason I remember both fans running on "low" speed at a certain temp, then kicking onto "high" speed at a certain temp. I also think they turn on high speed when the a/c is on.

I dont think one shuts off and the other turns on...but again, I could be mistaken. Looking at the diagram now...but Im busy at work and Im having a hard time picturing what goes on exactly haha. Its a 3 relay set up...

Just for visual entertainment. (I know it doesnt answer your actual question about temps )



I THINK when the fans are on the low speed circuit, they run in series. Giving them their slower speed. Then when high speed is needed, the PCM kicks on two other relays, that run each fan off of a 12v feed, parallel, making them run at full speed.


J.

Zepher

iTrader: (1)

looks like they run in series in low speed and in parallel when in high speed.

cam-

I found this out the hard way as Im only running one fan so i figured I'd only hook up the low speed fan and it worked great for about two weeks when all of a sudden my engine temps started climbing like MAD so i peeled over and my fan was off and Im

So i let it cool down it was never in danger it just heated a ways up from the thermostat temp ( 160 ) and when I fired it back up I let it idle a while and the fan came on so I thought hmmm wiring problem ( as in mine not a tech issue but an installation issue was what i was thinking ) I got home and before I started tearing up my harness I logged on over at tech and there was a few of us at the same time having similar issues. Thats when i found out that when high speed goes on, low speed goes off.

The fix was insanely simple I just hooked up both the high and low speed circuits to the same single cooling relay I have as I only have one fan and voila problem solved

Anyways its in the sticky over there somewhere. Speaking of sticky the LS1tech stickies are wretchedly confusing and in dire need of some re-work ala JRP he was/is the sticky MASTER. Very well thought out and organized he is sorely missed

( not dead just not LS1'ing anymore )

I H8 WWD

iTrader: (5)

I keep seeing first fan turn on 220*-226* and second fan turn on 238*-240*. So it looks like the same temps for our 3rd gens.

one92rs

iTrader: (5)

man i hope i remember this right. but i think the fans run seperate from the factory. a/c on not up to temp one fan comes on. no a/c and up to first low temp one fan and the second temp up both fans come on.

when i built this harness a while back (years) it worked different.
no a/c first temp fans on low. high temp fans on high. a/c on not up to temp one fan on. a/c on and up to either temp both fans on high.

here is a paste from ls1tech
Stock -
Low Fan on/off - 226.41*F / 219.17*F
High Fan on/off - 233.59*F / 227.33*F

and here is what hypertech recomends
________195
________ON______OFF
F1______209F____200F
________98.3C___93.3C
F2______219F____210F
________103.9C__98.9C

________180
________ON______OFF
F1______194F____185F
________90C_____85C
F2______204F____195F
________95.6C___90.6C

________160
________ON______OFF
F1______184F____175F
________84.4C___79.4C
F2______194F____185F
________90C_____85C

Zepher

iTrader: (1)

I just examined that Diagram again and there is only 1 way 1 fan can come on.
The Right Engine Cooling Fan is the only one that can come on by itself, and it will be on High Speed.
any other mode will have both fans running Low or running High.

There is no way that the Left Engine Cooling Fan can run by itself.

Now, is Left and Right sitting in the car or Standing in front of the car looking at the Engine?

cam-

This has been argued a thousand times. Read this link. Follow instructions and you'll be happy

http://www.ls1tech.com/forums/conver...gram-here.html

If your running a single fan just run both fan outs from PCm to the same trigger on the relay and it works fine. Three years not an issue for me

five7kid

iTrader: (14)

Okay, long time since I posted this.

I've only seen for sure one fan come on, and that was at 239 degrees. I was "running in" the 9", and flushing the crankcase at the same time. I had a fan in front of the car, and the one fan finally came on and cycled a few times.

Not sure if I have a relay issue (using a swap relay/fuse box), fan issue, or PCM wiring issue. It sure would be nice to have the fan come on earlier, though, especially at the track.

Not sure when I'll be able to track this down. But, I'm getting the PCM reprogrammed for Berlinetta #1's LS1/4L60E soon, and knowing what set points to tell him would be nice as well. I might get a spare from him for this car also.

A manual switch wouldn't be a bad thing to have, either.

Pocket

iTrader: (24)

Manual override switches are simple to install too. The PCM grounds the circuit, so tee into both PCM wires and take them to a two pole switch then to ground

Klortho

I know on my LT1 fans (I used the fusebox out of one) there are 2 relays, one for the driver side fan and one for the passenger side. I had a problem with mine not coming on until 240 and turned out I had one wired wrong not letting it ground properly to start the fan that comes on at 220. The third relay is for when the A/C is on, it turns both fans on at the same time to keep airflow moving across the radiator and condenser at a slow speed, then when the PCM tells the fan to come on for actual cooling purposes, it hits the actual fan relay turning it on high speed (at least that's what I've noticed when watching my '98)

five7kid

iTrader: (14)

{edit - I need to think this through some more}

five7kid

iTrader: (14)

Okay, 4th try at trying to type this up.

The factory system runs both fans when Cooling Fan Relay 1 Control is engaged, which provides ground to the Cool Fan 1 Relay magnetic circuit, which puts battery voltage to the Left Engine Cooling Fan, which is grounded through the Cool Fan 3 relay to the Right Engine Cooling Fan power - meaning the fans are in series and will run slow (the Right Engine Cooling Fan ground is direct to chassis ground).

When Cooling Fan Relay 2 & 3 Control is engaged, it switches the Left fan ground to actual ground. The Cool Fan 2 Relay is also energized, which powers the Right fan directly. However, there is nothing to power the Left Engine Cooling Fan, so the only way this can work is if Fan Control 1 is engaged along with Fan Control 2 & 3, or there is a missing circuit from the Cooling Fan Relay 2 & 3 Control to the Cool Fan 1 Relay magnetic circuit.

Now, I know that is NOT how my system is wired. . .

Both of my fan motors are grounded to chassis, which is how I remember the swap fuse/relay box instructions saying to wire them. So, either Cooling Fan Relay 1 control isn't working (which should turn on at least one of the fans at the lower temp), or I've got a defective fan motor or circuit. I did ohm both motors, and they both checked out the same (although I have never seen them run - bought them used from a TGO member).

Or, I didn't understand the swap wiring circuit. I don't think that's the case, but I'll have to go through it all again to try to figure it out.

one92rs

iTrader: (5)

i think i was thinking about an aftermarket harneess i used on my 2002 truck. it would turn on one fan with a/c only. both fans on high with a/c and temp. with coolant temp is was both low and then both high. this below was in the tech post from a service manual. from what i know and believe that they work --
both low when low temp is reached--relay one energized.
both fans on high high temp is seen--relay 1,2,3 all energized.
a/c signal only fans on low-relay 1.
temp and a/c both fans on high--relay 1,2,3

Engine Cooling Fan Description - Electric
The electric cooling fans are used to cool engine coolant flowing through the radiator. The fans are also used to cool the refrigerant flowing through the A/C condenser.

The electric cooling fans are controlled by the PCM. The PCM controls the ground path for the three cooling fan relays. The relays are used to control the high current flow to power the cooling fan motors. Both fans operate together. When minimum cooling is required, the PCM energizes cooling fan relay #1 and both fans operate at low speed, since the fans are connected in series through cooling fan relay #3. Cooling fan relay #2 is open (not energized) and is not used for low speed operation of the fans. When maximum cooling is required, the PCM energizes all three cooling fan relays. The left fan is still powered through cooling fan relay #1, but is now grounded through cooling fan relay #3. The right fan is now powered directly through cooling fan relay #2 and both fans operated at high speed.

The PCM will also enable the cooling fans after the ignition is turned off. When the engine coolant temperature exceeds 113°C (235°F) and the ignition is turned off, the cooling fans will be enabled on low speed for 150 seconds.

Low Speed Cooling Fans
The low speed cooling fans are controlled by the PCM based on the following inputs:

The A/C system.
The Engine Coolant Temperature (ECT) sensor.
The Vehicle Speed Sensor (VSS).
The PCM will turn the cooling fans on low speed when any of the following conditions exist at idle:

Certain PCM Diagnostic Trouble Codes (DTCs) are set.
The ECT above 108°C (226°F).
The A/C high side pressure above 215 psi.
Once the low speed fans are turned ON by Engine Coolant Temperature, the PCM will turn the fans OFF when that temperature has dropped about 4°C (7°F). If the low speed cooling fans are turned ON by high A/C head pressure, the PCM will turn the fans OFF when the pressure has dropped to 190 psi. The minimum ON time for the low speed cooling fans is 50 seconds.

The cooling fans are turned OFF at certain vehicle speeds. Adequate airflow through the A/C condenser and radiator occurs with vehicle movement to properly cool the A/C refrigerant and engine coolant without the assistance of the cooling fans.

High Speed Cooling Fans
The High Speed Cooling Fans are controlled by the PCM based on the following inputs:

The A/C system.
The Engine Coolant Temperature (ECT) sensor.
The Vehicle Speed Sensor (VSS).
The PCM will enable both fans on high speed when any of the following conditions exist:

Certain PCM Diagnostic Trouble Codes (DTCs) set.
The ECT above 112°C (234°F).
The A/C high side pressure above 248 psi.
Once the high speed cooling fans are turned ON by the Engine coolant temperature, the PCM will turn the fans OFF when that temperature has dropped about 4°C (7°F). If the high speed cooling fans are turned ON by high A/C head pressure, the PCM will turn the fans OFF when the pressure has dropped to 208 psi. The minimum ON time for the high speed cooling fans is 30 seconds.

Klortho

IIRC what happens is the PCM sends a ground out to the relays which closes them and sends the power to the fans. My fans are grounded to the chassis as well. I would check and make sure you are getting the right signal from the PCM at the relay to ground the relay out, it took me a while to figure it out as well but you'll get it.

five7kid

iTrader: (14)

Exactly. That's what Ghetto's diagram shows.

That's not what the diagram shows.

That would require the temp to be above the "on" value. I'd have to get the engine warm enough that the low speed signal is grounded.

I'll see what I can figure out. Before that, I need to get this new BMR torque arm mounted. . .

one92rs

iTrader: (5)

you are right. only one frame ground is present in the original wiring diagram. but both could be since the first fan connects to the second one ground. it would be the same.


.

ghettocruiser

iTrader: (4)

There is only one ground to the chassis IIRC. The right fan is always grounded at the chassis.

When running in low mode, the power goes from the PDC, through the left fan, then over to the right fan, then to ground. Series.

When running in high mode, the relay skips the bridge from one fan to the other, and grounds the left fan on the same ground as the right fan. Parallel.

Its kind of complicated to trace it all out and imagine it in your head.

Setting up a manual switch is very easy as was already stated. I need to set my temps a bit lower in the tune still, but I plan to put a manual override switch on it too. Just because.

J.

Klortho

Oh you can test to see if they relays are working right, what I did was took the wires that goto the fan relays and just grounded them to a bolt (fender bolt, strut tower bolt) which showed me which colored wire went to which fan.

one92rs

iTrader: (5)

true but both could be to ground since the channel is the same. the wire or fan knows no different. when onlyy the first relay is set to on the grround from the first motor goes thru power on the second one which is the series connection. the actual ground on the second fan to frame is not present. in all actuallity there can be two seperate grounds to each fan. look at the diagram closely. there is no frame ground to the first fan with the first relay to on. it is series due to ground connection thru the second fan. best thing to do is ground the pcm connection and see if they come on.

five7kid

iTrader: (14)

If you ground both fan motors to the chassis in the factory scheme, only the "left" fan will run in "low" mod, and it'll run full speed. "High" should still work the same with both fans going full speed.

I still need to figure out how my box is supposed to run the fans. I don't think it's like the factory set-up, and given the temp that the fan came on, indicates one fan isn't working (for one of the reasons given above).

one92rs

iTrader: (5)

ok let me try it this way.

power to both fans comes from battery. now!!
there are two grounds to the first fan. the first ground goes thru the power lead of the second fan. which is series. this causes both fans to run in series and share power. 12 volts/2=6 volts each. low speed.

now. when the other relays are turned on the ground from the first fan to power on the second fan is bypassed. this causes the first fan to go to frame ground as well as the first fan which is always graounded to frame.

actually ghetto is right. both fans cannot go to frame ground. MY BAD!!!

the actual frame ground to the first fan goes thru relay #3. middle relay.

so i suppose one way to show it is this.
a relay. 85-pcm ground siganl
86--10 amp ignition power
30--ground from the first fan
87a--this one goes to the power wire for the second fan--constant connection--series
87--this one can go to frame ground as well as the second fan ground.

when the pcm signals high speed the 30 to 87a is cancelled. then the power goes to 30 to 87. this is frame ground to both fans which is high speed.

one92rs

iTrader: (5)

this may be a better way to show it
relay#1
86--power from ignition-shared
85--pcm signal--ground
30--battery +
87--+ to first fan

relay#2--farthest to the right
86--ignition power--shared
86--pcm ground--shared with relay#3
30--battery +
87--power to second fan--from 87a on 3rd relay( first fan ground wire)


relay#3
86--power from ignition( shared)
85--pcm signal for high speed
30--ground from first fan
87a--to 87 of second relay--series connection for low speed
87--frame ground or shared ground with second fan.


if you know how tyo wire relays this will help out. i have built this circuit many times and it works perfect. when i didnt install it on an ls1 or truck pcm ( pin 42 and 33 on truck ) i used two hayden controllers and switched my grounds to frame and used the controllers for my ignition signals on 86.

one92rs

iTrader: (5)

like this pick because of the color changes

ghettocruiser

iTrader: (4)

That diagram is MUCH easier to understand. I was trying to find that one when this thread first came up I think.

Part of the problem is, some of us are used to thinking of switching the postive 12v versus switching the grounds. So until you wrap around that, you sort of see power going to everything and it gets confusing.

I think the upper diagram is more accurate in terms of how things are actually wired...but that last diagram is much easier to visualize and understand. Good post.

J.

one92rs

iTrader: (5)

actually it is the same diagram with colors added. i suppose most people veiw it as everything needs to be grounded to frames like a switch. not on motors. it is grounding thru the other motor but this is causing it to share power. it took me a little bit till i read the relay numbers. after that i wired my first one up and then understood it exactly. i think the two grounds people are saying they have are the 2nd motor ground and then pin 87 off the thrid relay ground. as for both motors being grounded to frame all the time no. this will be high speed only when commanded.

five7kid

iTrader: (14)

I got caught in the "switch turns on power" trap. One of the reasons I deleted my original response and started over.

This latest version of the diagram is a little confusing because they have the Cooling Fan 3 Relay drawn "backwards". Convention is to put the magnet coil on the side that the switch moves to when energized, while this diagram has it on the un-energized side. The "normally closed" terminal of that relay takes the Fan 1 "ground" to the power side of Fan 2, which, since Fan 2 has no direct power in that mode, puts the fan motors in series.

The diagram in Post #3 by ghettocruiser shows the relay properly drawn. Add colors to that if it helps you, but that is the properly drawn diagram.

(And I finally see that he also said all three relays are energized for fan "high", which makes sense. )

one92rs

iTrader: (5)

i edited this pic a little. i think this is the wire connection that has people confused. look at the lime green line i drew on it.

five7kid

iTrader: (14)

What confused me about that was the 12v battery power above Fan 2 - but, there is a relay isolating that power - duh.

(And you didn't "fix" Cooling Fan 3 Relay...)

one92rs

iTrader: (5)

ok to draw the line was enough forr me.

hey five7 if you need some more help lemme know. i have built these harnesses before and they worked great.

one92rs

iTrader: (5)

red= battery power positive.
yellow= ignition power--key on
blue= pcm ground signal
purple= shared power--series connection--both fans on low number 1 relay power only


relay #1--low speed only or a/c signal only
relay 1,2,3--high speed or a/c and temp on signal

see if this helps some. for you five 7

five7kid

iTrader: (14)

Perfect!

I haven't had time to look mine over, but I'm sure it'll get figured out eventually.