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Fastbird
10-30-2009, 09:35 PM
Got a problem --

The Coolant Fan circuit. The Fast Track harness has a single wire labeled cooling fan coming from pin B-10 on the XFI box. The instructions say to splice this into pin B-04 on the GM harness. This splices it into the primary cooling fan relay control, which jives, but........

By splicing it in, won't that leave the factory ecm to control the fans also, and with the given faults from the XFI taking control of things kick them on all the time?? And if I simple disconnect that fan wire from the GM computer and have the XFI ONLY controlling the primary fan, will the secondary fan still function correctly from the factory computer (say when temps get too high, A/C is on max, ect)????

Anyone know this?
The SRZ
10-30-2009, 10:27 PM
Sean, I'd use a fan switch to control the 2nd fan. Mine USE to work correctly w/ one fan kicking in then the other if it got too hot and this was w/ the wiring hooked directly to the xfi and a seperate fan switch. Now though, they both just kick on. Fine by me. Gets cooler quicker. :)
Fastbird
10-30-2009, 10:42 PM
Sean, I'd use a fan switch to control the 2nd fan. Mine USE to work correctly w/ one fan kicking in then the other if it got too hot and this was w/ the wiring hooked directly to the xfi and a seperate fan switch. Now though, they both just kick on. Fine by me. Gets cooler quicker. :)

See, I'm half tempted to just leave it be and run my piggyback adapter and old stock chip, but then with the faults being thrown by lack of stuff on the stock ECM they would be running all the frikkin' time.

I'm also looking at completely rewiring the whole fuel pump setup so I can hook up both pumps to the XFI now. I'm talking XFI to the relay, and battery through relay to the pump. I've got a Racetronix Harness so it shouldn't be too hard to adapt that for running the XFI through it, and then adding another. But I digress........

What fan switch are you using and do you have any schematics on how you hooked it up? I feel that I"m going to HAVE to remove control from my stock ECM, but then the A/C fan capability will be lost too and I MUST have that. It's a conundrum I tell you!
The SRZ
10-31-2009, 02:04 PM
Speed specialty fan kit is what I have. Not even sure if those guys are still around. I do have the schematics but I'll have to have them scanned at work monday.
Fastbird
10-31-2009, 02:09 PM
Cool man, I appreciate it. I've got other issues to work out now but think that I'm getting to the bottom of them.

Silas, are you absolutely sure that your knock sensor is working with the wiring spliced in at B-whatever on the factory harness. I talked to a guy at Fast today who said that the XFI is designed to take inputs from a mid 80's Spark Knock module from GM, not the knock sensor directly.