Results 1 to 8 of 8

Thread: Fan on below cutoff temps.

  1. #1

    Default Fan on below cutoff temps.

    My fan has started to come on when first starting, not the little blip they do at first key on, but it stays on. It doesn't do it every time, probably 80% of the time. My CTS reads almost 20°F more than the MAT, so I figured maybe it was going bad, so I bought a new one, it reads high also (ACDelco 213-4514). I noticed when I plug in the CTS connector with ignition on, I hear the IAC buzzing, not sure if that's normal, maybe due to adding resistance in the wiring. I don't know what the ECU does normally at key on to bump the fan, but could that be causing it to stay on?

  2. #2


    If everything is wired properly, there should not be any sort of "bump of the fan" when you turn the key on. The Terminator X outputs are all ground triggers. So at a given temperature the ECU pulls that output to ground, which, if your fan relay is wired correctly, will turn on the fan.

    Fan relay wiring should be as follows:
    Pin 86 is switched ++12V
    Pin 85 to Terminator X output
    Pin 30 Power source +12 volts
    Pin 87 Positive side of the fan motor

    Negative side of the motor should go to a good ground or, ideally, to the negative side of the battery.
    Also make sure you have the right sensors selected in the Sensor ICF. This could be throwing off the calibration. Andrew

  3. #3


    I think I found the problem. The Terminator X comes with some stuff pre-pinned, like two fans, IAC Kick, something to do with the A/C. If you're using A/C, and using Holley's wiring for it, when the A/C is on, the fan runs all the time. I was original running a tune from my LT, and only running one output, and one input. Nothing pinned to the other 6. I'm using a tune built from the 3.5" touchscreen temperature, so the other stuff is pinned. I'm guessing where I had the spare Inputs/Outputs coiled one was touching ground, which set a signal to the ECU that A/C was on. There isn't much info on it, just happened to notice on the LT where the fan control is, you can uncheck a box for A/C. MY HP's all gave the fan a bump on startup, just figured that was normal. I bought a new ACDelco CTS, it reads high also, digging around seems to be others with the same problem.

  4. #4


    @jimbo72: I always make sure that any I/Os that aren't actually being used are turned off. Andrew

  5. #5


    I don't think you can do that from the 3.5" touchscreen, can you?

  6. #6


    I don't know. I don't ever work with the handheld. Andrew

  7. #7
    Join Date
    Dec 2009


    Neither do I. When you have a Sniper EFI problem, it's time to buy an inexpensive used Windows laptop (to download Sniper EFI software, retrieve the GCF from ECU, engine tuning & datalogging).
    May God's grace bless you in the Lord Jesus Christ.
    '92 Ford Mustang GT: 385" SBF, Dart SHP 8.2 block, TFS T/W 11R 205 heads, 232°-244° duration/.623" lift/114° LSA camshaft, 12:1 C/R, TFS R-Series FTI ported intake, BBK 80mm T/B, Dominator MPFI & DIS, 36-1 crank trigger/1x cam sync, 200A 3G alternator, Optima Red battery, A/C, 100HP progressive dry direct-port NOS, Spal dual 12" fans/3-core Frostbite aluminum radiator, Pypes dual 2.5" exhaust/off-road X-pipe/shorty headers, -6AN fuel system plumbing, Walbro 255 LPH pump, S&W subframe connectors, LenTech Strip Terminator wide-ratio AOD/3000 RPM converter, B&M Hammer shifter, FPP aluminum driveshaft, FPP 3.31 gears, Cobra Trac-Lok differential, Moser 31 spline axles, '04 Cobra 4-disc brakes, '93 Cobra booster & M/C, 5-lug Bullitt wheels & 245/45R17 M/T Street Comp tires.

  8. #8


    I have a LT, actually two, both are shot. The reason I'm using a 3.5" TSLCD tune temporarily, new LT is on order.

Posting Permissions

  • You may not post new threads
  • You may not post replies
  • You may not post attachments
  • You may not edit your posts
About us
Holley has been the undisputed leader in fuel systems for over 100 years. Holley carburetors have powered every NASCAR® Sprint® Cup team and nearly every NHRA® Pro–Stock champion for four decades. Now, Holley EFI is dominating the performance world as well as our products for GM's LS engine. Holley's products also include performance fuel pumps, intake manifolds & engine dress–up products for street performance, race and marine applications. As a single solution, or partnered with products from other Holley companies - Hooker Headers, Flowtech Headers, NOS Nitrous, Weiand, Earl's Performance Plumbing, or Diablosport - Holley products can give you the edge you need over the competition.
Join us