Can anyone tell me how to wire a cooling fan relay with the Holley Commander 950? I know it connects to the C1 termanal but I have no idea after that.

 

That pin (C1) is pulled to ground to turn the relay on. Supply ignition switched +12 volts to a relay coil terminal and attach the other relay coil terminal to pin C1. The relay will close the N.O. contacts upon the 950 activating the cooling fan.

Holley also has a harness for this, part # 534-134 Cooling Fan Relay kit

Don't know what is included.

RBob.

 

You get a terminated harness with a relay & fuse. You just have insert the wire into C1 on the ECU header connector & mount the relay & fuseholder, then the hot to the fan. Kinda pricey for what you get but it is plug & play. If you have the right connector it would be easy to wire it yourself.

 

If you still have the stock fan wiring/relay intact, just hook the green/white wire from the fan relay to C1. That's how mine is setup.

 

I just found out I need to set up a knock sencer circut to. Any body have a wiring diagram for this too?

 

Over on diy-efi.org/gmecm there are wiring diagrams for stock ECMs. Find one for the '86-'89 TPI or the '89-'92 TBI f-body setup. They are wired in the same manner that you need to wire yours.

RBob.

 

Holley makes a knock sensor kit for the 950, plug in, and it's not too expensive, under $50 i think, hooks up directly, and is controlled by the 950 with adjustable retard rates. You say you need too, why is that?

 

I am installing a new harness and here is what I have found.
If you already had the knock sensor and fan relay simply
take the input signal wire that goes to the old ecu from each circuit and place into corresponding location on new ecu.