Electrical lesson needed

[chtampa]

I have a non Mopar truck that I am slumming with right now and need to wire an electric cooling fan. My EFI has Fan Control and I want to use it.
The single fan is two speed
Low has to be on before high speed can come on
The EFI has a Fan1 wire and a Fan2 wire to control both speeds programmable by temperature
The EFI Fan Control is negative completing the circuit to ground
I have two, five wire Relays, one for each speed
The info that I have gotten says that the + & - have to be reversed somehow
I have posts 30, 85, 86, 87, 87a.
I am on the short bus when it comes to wiring

Can anyone explain what goes where? Explain it like you are telling your wife.

 

[NoCar2023]

Does this help?

 

[WileERobby]

Can anyone explain what goes where? Explain it like you are telling your wife.

 

[chtampa]

Does this help?
View attachment 1252598

Allow me to study!

 

[1 Wild R/T]

Allow me to study!

Everything you need is right there..

 

[kiwigtx]

I am on the short bus when it comes to wiring

There's even an electrical pun in that sentence.

Short bus.....

 

[Demonic]

 

[Don Frelier]

If both low and high are actuated at the same time then the 12 volt power to the high speed coil in the diagram needs to be wired differently.
The circuit shown above interlocks so that high relay will only be energized when the low speed relay is off.
I'll see if I can mark it up to show more clearly.

 

[chtampa]

If both low and high are actuated at the same time then the 12 volt power to the high speed coil in the diagram needs to be wired differently.
The circuit shown above interlocks so that high relay will only be energized when the low speed relay is off.
I'll see if I can mark it up to show more clearly.

Thanks. The EFI turns one on at like 180 and then the other at like 200. So it seems that it will be covered there.

I missed the short pun, I must be tired.

 

[Don Frelier]

Then wire both coils with 12Volts similar to the way shown for the high speed relay.
Fuzzy gray below is removed.
Just make sure that Fan 1 cut in temperature is lower than Fan 2.
You also should put fusing or breakers in for overcurrent protection.
Usually 30 amps is good.

 

[chtampa]

Does this help?
View attachment 1252598

Wired it like this and fan doesn't come on. Didn't see the second , changed, schematic. Will try that one.

 

[Don Frelier]

You can easily test your wiring by grounding pin 85 on each relay. (which is what the controller is doing)

 

[chtampa]

You can easily test your wiring by grounding pin 85 on each relay. (which is what the controller is doing)

Thanks

 

[bm02tj]

I would get the 12v power for high from 87a on low speed as it is only hot when off

 

[chtampa]

I spoke with MSD and they gave me the following:

Relay #1 (Low)
85 PCM Control Low Speed (pink)
86 & 30 Power (red)
87 Low Speed Fan Wire (gray)

Relay #2 (High)
85 PCM Control High Speed (tan)
86 & 30 Power (red)
87 High Speed Fan Wire (brown)

He also said that 85 & 86 were interchangeable.

Anything sound off here?

 

[NoCar2023]

That should work. I believe that is the same way Don recommended to wire them.
The diagram I posted will run one speed at a time, (when the ECM commands the high relay on the low relay is disabled) this a system I have used for a LS swap I did in the past with a GM ECM—can't remember why it was done this way, I have done a few...
What MSD system and fan are you working with?

 

[chtampa]

That should work. I believe that is the same way Don recommended to wire them.
The diagram I posted will run one speed at a time, (when the ECM commands the high relay on the low relay is disabled) this a system I have used for a LS swap I did in the past with a GM ECM—can't remember why it was done this way, I have done a few...
What MSD system and fan are you working with?

Yep, we changed one wire and that did it. Thanks all!
MSD Atomic and a Derale Fan.