# Sniper EFI cooling fan output



## RRconductor76 (Nov 29, 2016)

I recently installed the Holley Sniper Quadrajet EFI on my 69 GTO. I installed the Taurus 2 speed cooling fan with a Volvo fan controller and hooked up the low speed to the Sniper #1 output and the high speed to the #2 output. The high speed works great just like it should ( tons of air). The low speed #1 output though is not coming on. If I run my test light from the negative battery post to the low speed wire at the controller I can hear click and the fan comes on. Anyone that has installed the Sniper EFI have any idea what could be going on? Anybody really! Thank you Allen


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## jtpeters (Aug 29, 2021)

I'm sure someone here can provide an answer, but if you don't get one, try:
Sniper EFI - Holley Performance Products Forums


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## RRconductor76 (Nov 29, 2016)

No one out there running Holley Sniper EFI with an electric cooling fan?


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## GTO44 (Apr 11, 2016)

RRconductor76 said:


> No one out there running Holley Sniper EFI with an electric cooling fan?


Sorry haven't been on in a while. Did you test the Holley output #1 to make sure it's sending a ground output when the "temp on" temperature is met?

If it is, then the issue is with something past that and not the holley. It would be helpful for you to layout exactly how you have it wired with the controller. Also the part number of the controller and fans will be helpful in diagnosing the problem. 
Also, you dont need an additional controller to operate the fans in a "2 speed" mode. You can accomplish the same thing with 3 simple automotive relays. It's actually how the factory setup the 2 speed fan function on '04-'06 gtos.


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## RRconductor76 (Nov 29, 2016)

I am using a Volvo fan controller (







the single red wire on the right goes to the positive battery post with a inline fuse, the red and green wires on the left go to the 2 speed electric cooling fan ( red- high speed, green- low speed), the middle plug #1 blue wire is the low speed and is wired to the #1 output light green wire from the Holley Sniper efi and the #2 white wire is wired to the #2 output blue wire from the Sniper efi. Using my test light from the negative battery post to the #1 output light green wire the test light comes on and the fan will come on.


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## GTO44 (Apr 11, 2016)

So just to confirm. You ARE getting a ground signal from Holley OUTPUT#1? Just a simple yes or no is what im looking for. Use a volt meter and report back. Sounds like when you use your test light it's grounding thru the bulb and triggering the low speed fan. But we need to first confirm that OUTPUT#1 is actually sending a ground signal.

Also what are your on and off temps for each of the fan outputs?


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## RRconductor76 (Nov 29, 2016)

No, volt meter shows 1.5 on the #1 12.45 
on the #2


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## RRconductor76 (Nov 29, 2016)

Blue wire will trigger either one (#1 or #2) on the middle relay


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## RRconductor76 (Nov 29, 2016)

Sorry I got the output wires from the Sniper wrong in the earlier post. The light blue (low speed) from the Sniper is going to the blue (low speed) wire on the middle relay. The light green (high speed) from the Sniper is going to the white (high speed) wire on the middle relay. The light green wire is still the one not working.


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## GTO44 (Apr 11, 2016)

Did you enable Fan2 output in the software? Also what are your on/off temps for both fans?


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## RRconductor76 (Nov 29, 2016)

I don’t know what your referring to as enabling it in the software. The low speed #1 is set to turn off at 160 and turn off at 180 high speed #2 is set to come on at 185 and off at max temperature.


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## GTO44 (Apr 11, 2016)

So lets go back to JUST the sniper outputs. If you probe OUTPUT#1 (light blue), and OUTPUT#2 (light green), BOTH should be sending ground above your FAN2 turn on temp (looks like it's 185deg).

So get the car to 190deg, have the key on or car running (so the holley screen is on) and probe both OUTPUT#1 and OUTPUT#2 and verify they are both proving ground. 

When you responded in post#7, you said you measured voltage. The Sniper does not output 12v signal on OUTPUT#1 and OUTPUT#2, so I assume you were measuring the fan outputs from the Volvo controller. We need to verify the Sniper is indeed proving ground on OUTPUT#2 when commanded.


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## RRconductor76 (Nov 29, 2016)

Ok , so how should I check to see if they are putting out negative?


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## GTO44 (Apr 11, 2016)

Set your multi meter on continuity or diode mode. Put one lead on a known ground (either chassis or batt negative) and the other lead on Sniper OUTPUT#1 and then on Sniper OUTPUT#2. The multi meter should change from 0 to 1, meaning you have continuity with ground. If both outputs read 1 when engine is above your FAN 2 "Turn on" Temp, then we can rule out the sniper being the issue. At that point it's a problem with the volvo controller or Taurus fan. 

Here's what the symbol will look like:


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## RRconductor76 (Nov 29, 2016)

Green wire is showing nothing.


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## GTO44 (Apr 11, 2016)

RRconductor76 said:


> Green wire is showing nothing.


So that is your issue. Take a picture, if you can, of your OUTPUTS screen so I can see the exact Fan on and off temps.

This is the screen im referring to:


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## RRconductor76 (Nov 29, 2016)




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## GTO44 (Apr 11, 2016)

So there's the issue.

Third line down.... Fan #2 On Temp is 260. Change that to 195 deg.

Fourth line down.... Fan #2 Off Temp is 195. Change that to 185 deg. 

Now get the engine to at least 195 degrees and test OUTPUT #2 again. It should now be providing ground and should turn on your high speed fan.


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## RRconductor76 (Nov 29, 2016)

Ok I will try it.


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## RRconductor76 (Nov 29, 2016)

Well didn’t work,but did find out that it looks like the light green wire shorted out at the Sniper 10 pin connector. Not receiving anything from the ECU.


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## GTO44 (Apr 11, 2016)

RRconductor76 said:


> Well didn’t work, but did find out that it looks like the light green wire shorted out at the Sniper 10 pin connector. Not receiving anything from the ECU.


That's not good! 

As an alternative...

You could keep the sniper OUTPUT#1 as one trigger and use a temp sender that provides ground as the second sensor.

Also, there has to be a reason OUTPUT#2 shorted out. I'd do some testing on that Volvo controller (especially if it's used) to make sure it's functioning correctly. Don't want to hurt the sniper.


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## RRconductor76 (Nov 29, 2016)

Precisely what I was thinking. Does the Sniper use the temperature from the sender for anything other than the fan outputs?


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## RRconductor76 (Nov 29, 2016)

I don’t believe there is anything wrong with the Volvo relay as the blue wire will work the low speed or the high speed. But I will check it.


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## GTO44 (Apr 11, 2016)

RRconductor76 said:


> Precisely what I was thinking. Does the Sniper use the temperature from the sender for anything other than the fan outputs?


Yes, the sniper temp sensor is one of the sensors responsible for fueling. The ECU uses a combination of coolant temp, air intake temp, throttle position % (TPS) and MAP sensor data to calculate volumetric efficiency and fuel enrichment.

The Fan output is just an added bonus of having the coolant temp sensor data available.


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## RRconductor76 (Nov 29, 2016)

So the Sniper will still get the information it needs and the fan output is the only thing that won’t work.


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## RRconductor76 (Nov 29, 2016)

Can I tap into the light green wire coming from the temperature sender and use a relay to activate the controller.


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## GTO44 (Apr 11, 2016)

RRconductor76 said:


> Can I tap into the light green wire coming from the temperature sender and use a relay to activate the controller.


No, dont do that. The temp sender is resistance based. If you tap into it, it will change the resistance the ecu is expecting and will give skewed results. Plus you need a sender that only gives a ground signal at a specific preset temp.

Here’s one that provides ground at 200deg and off at 185deg. You would just wire the the tab on the sensor to the white wire on the volvo trigger for high speed control.

Amazon.com: Fan Temperature Switch 200 to 185 Degree Electric Engine Cooling Fan Thermostat Temp Sensor Switch with 3/8" Pipe Thread for 10" 12" 14" 16" Fan : Automotive

I would keep the low speed blue wire input connected to the Sniper OUTPUT#1 blue wire. That way you can have control over when the first fan comes on. For example, If you have a 160 thermostat you may want to bring the low speed fan on sooner than your current setting of 185. You’ll be able to do that with the handheld and not have to replace the sender.

The other added benifit of having the sniper control low speed fan is for A/C. You can wire the compressor signal to the Orange wire, INPUT#1. (You’ll have to use a relay to change it to a ground signal but its easy). That way the sniper can kick the low speed fan on when ever the A/C is turned on, even if the car isnt up to temp.

Unrelated, but another great benefit… it will also give you the ability to use the A/C kick function, which speeds up the idle to offset the load of the compressor when the A/C turns on or cycles.


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## RRconductor76 (Nov 29, 2016)

That’s some great information but I don’t have any open spots on the intake manifold for another temperature sender.


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