fan hi and low relay questions

[xracerx13]

Is it true that when the high speed fan relay is triggered by the fan temp switch that the low speed fan relay continues to stay on? or does it turn off normally? in a normal stock configuration. ..
I would think that the ECM trigger to the low speed relay stays on even if the high speed relay turns on but not sure.

So with that in mind...
I installed the intrepid fans with Casper's harness when I got the Cold case radiator.

The Caspers harness triggers both fans on when only the low speed relay kicks on.
Yes I have the .5 sec delay option for the second fan. BUT
It is overkill here in NY most of the time and I don't use the  A/C. 
Highest temps I saw were 168 degrees doing 80mph when I turned the fans off completely because I can the way the KB switch is wired, and stays around 164 degrees street driving with both fans on, both tests in 85 degree weather .
My turn on temp with the Maxeffort is 163 so it cycles a little more than I want. when the fans are on they drop the temp to 160 then they are off and then on again at 163 and it does this often in cooler weather.

\Ready here it comes 

I have a Kenne Bell low/high fan speed chip switch and when I click it to High both fans turns off.
The way its wired is that the switch intercepts the trigger wire to the low speed relay from the ECM and uses it to turn on the high speed relay, so its either or relay but never both.
So when the high relay is on the low is completely off because the ecm wire no longer makes contact with the low speed relay. Did they do it this way so both were not on together for a reason?
Attaching  KB directions for visual.

I'll probably answer my own question here but. If I jumper the 2 green wires back together even if its at the switch...that would be the 2 upper in the pic.....then the low speed would work all the time like stock when the ECM says turn on and I could flip the KB switch to high and also turn on the high speed relay. If it don't hurt anything.
With a wire mod to Casper's harness i will add the center missing high speed wire that they don't have in their harness and run it from their side of the mating to stock plug to the second intrepid fan relay.

The question here is would it be to much on the ECM trigger wire to do it this way, triggering both high and low relays?
And does the low speed relay remain on when high is on in bone stock configuration without the KB switch?

Since each stock relay will run to trigger separate fan relays I don't see an issue in that regard but not sure if the one ECM trip wire can handle it even if its only triggering 2 relays.

[xracerx13]

try again with pic

[Scoobum]

Steve and Jeremy are the electrical wizards so they'll help you out. I took the easy way out and raided the dual fan from Jeremys yellow car...cuz it was plug and play...and snapped into the Fbody rad.

[Steve Wood]

I am not really sure what you are trying to accomplish but this is the way the factory fans worked  https://vortexbuicks-etc.com/fan.htm

Given that you don't have factory fans, I guess that is of no use to you.

Often, dual fans are separated by a time delay of a brief period of time to prevent overloading the relay and/or fuses with the start up current draw which is quite high compared to actual running draw.

I have dual Spal fans.  I installed them so that one was triggered by the factory low speed relay and I connected the second fan to the factory high speed relay so that it only runs when the AC is on OR if the car gets hot enuf for the high speed temp to kick it on.  It never has but then it gets really hot down here and I normally have the AC on so it comes on when that is the case.

I am guessing that if you want them both triggered by separate relays and coming on at the same time, the two relays would pull about 400 ma max.  You would have to ask Bob Bailey if the ecm can handle that.

If I wanted to turn both fans on every time (I don't because not only is it not needed, but because two spals make some roar) I would just substitute the factory relay for a 60 amp relay and run them off the low speed relay circuit.

[xracerx13]

I installed them so that one was triggered by the factory low speed relay and I connected the second fan to the factory high speed relay so that it only runs when the AC is on OR if the car gets hot enuff for the high speed temp to kick it on.  It never has but then it gets really hot down here and I normally have the AC on so it comes on when that is the case.

the above is what I want to accomplish. I have the caspers harness and it has 2 relays powered by the battery post, but it uses the low speed relay to turn those relays both on at once. Yes there is a delay for the second fan. BUT
If I use a switch inside the car to ground out the high speed relay then I can run a + from the high speed relay wire to the second fan relay like you did.
Sorry for the confusion. I don't want them coming on at the same time. I want to hit a switch if need be to have the second come on.

I was more curious to know if the low speed relay stays on all the time even if the high speed relay kicks on?
Are they independent of each other

[Steve Wood]

Yes it stays on

[xracerx13]

Ok good it stays on. Thanks Steve.

I just want it so if the car runs up to 210-215*, which it never will... there's the safety of the high speed fan relay coming on just in case I ever forget to flip the KB switch to high. Or if I use the A/C.

What I was getting at is that the KB switch instructions makes you cut the green ground wires coming from the ECM to the low speed relay and sharing the ECM ground signal with the high speed relay, so then the switch allows you to choose hi or low fan speed....but that was for a stock fan for bypassing the resistor.

I figure if it can do that.... then by joining the cut in the green wires I can still ground the high speed relay to turn 2nd fan on at any given moment while keeping low speed relay on.

So if you look at the KB instructions photo. the switch has a pink and black wire that attach to it. Top 2 terminals. I will be moving the pink wire to the center part of the switch, enabling low speed relay all the time (ECM on), and at the flick of the switch it would turn on the high speed relay when needed by stealing ground from the green ECM wires.

Yes I bought this 25 years ago and yes it worked so why not incorporate it. I already cut the green wires. right...
It just wont be low speed hi speed it will be 1 fan or 2 fans.

I just need to add the missing wire in the Fan harness I got from Justin at Caspers and remove the piggy back trigger wire from one relay and attach it to the new wire.

[~JM~]

I used this: http://www.casperselectronics.com/cart/index.php?route=product/product&path=7_53_54_10_14&product_id=36

[xracerx13]

Caspers fan hi/low switch doesn't work with their dual fan harness.
the dual fan harness has only 2 wires running to intrepid fan relays

[~JM~]

Seems to work fine on my car. Dual Spal fans with Casper's harness. All plugged in to OEM wiring connectors.