ECU dual fan wiring?

[jlwdvm]

I have a Speartech stand-alone harness for my LS3. I will be running dual fans and my ECU has a pair of wires coming out of it for each fan. My question is where does each fan wire coming out of the ECU go? The relays for the fans have a single wire labeled as sending unit.

[dontlifttoshift]

That's where they go. ECU is the sending unit, providing a ground signal to turn the relays on.

[jlwdvm]

Right, but there are 2 wires for each fan coming from the ECU harness. Do both wires go to the single fan relay sending unit wire, or is one a ground? One wire is striped and one is solid for each fan.

[Vince@Meanstreets]

Originally Posted by jlwdvm

Right, but there are 2 wires for each fan coming from the ECU harness. Do both wires go to the single fan relay sending unit wire, or is one a ground? One wire is striped and one is solid for each fan.

Each wire is a circuit for a relay. Should have one relay for each fan. Sounds like your relay set up is wired direct. But sending unit maybe referring to a block switch. No instructions?

excellent set up here to remove the guess work:
http://www.entropyrad.com/lsx-series...ontroller.html

[jlwdvm]

I have 2 AAW relays to use that were recommended by C&R (Built my rad with dual Spal fans for 69 F-body with LS)...one for each fan. My question is where do I run each of the 2 wires for each fan (4 wires total coming out of the ecu wire harness)? Maybe I have the wrong style relay?

[Vince@Meanstreets]

ok gotcha....


grounding circuit shared with switches. repeat for second fan

[jlwdvm]

Right...that looks similar to the directions that came with the relays. My question is: why dies my ECU harness have 2 pairs of wires coming out of it instead of 1 wire for each fan? Is one for a manual switch and one for a temp sensor switch? I tried to get a hold of Speartech, but no answer.

[dontlifttoshift]

Can you turn the key on. I think speartech gives you a 12 volt wire as well, I have only used his harness once.

One wire would go to 85 and one wire would go to 86 on the relay.

Found this http://www.speartech.com/v/vspfiles/...ns/LS58X4L.pdf

[jlwdvm]

BINGO! Thanks!