Another sniper Question

[spogshd 4]

Can anyone with some good knowledge on electrics please have a look at the attached  and tell me if I've set this out right of the holley sniper.

Sorry its just a rough sketch. Was thinking of using the feed to the relays from the ignition as a fuse block to also feed accessory's .

Any help would be appreciated.

 

Craig 

[aslanefe 333]

I do not understand what you are trying to connect to, but I connected the Sniper pump relay power input to battery directly and got 12V when running  (the pink wire) from the voltage regulator. My voltage regulator harness had a female bullet connector (that was not hooked to anything) which provided 12 V when cranking and running', that is what I used for pink wire.

[spogshd 4]

I think that red and green wire (904) on my diagram is going to your voltage regulator .

[aslanefe 333]

4 hours ago, spogshd said:

I think that red and green wire (904) on my diagram is going to your voltage regulator .

I believe so; the number 3 pin of the VR harness has a pig tail with a bullet connector on my harness which is blue/red wire. I put my fuel pump relay by the starter seloniod so the pig tail is within inches and every wire in Sniper harness is in the same shield all the way to fuel pump relay. So 904 on your diagram is 12V during cranking and run. I can't remember what blue and green from Sniper is for, I believe they provide ground signal for Sniper controlled accessories; in that case you can use them and 904 to trigger relays for stuff you want on during crank and run. But I would not get the main power to the relays from 904 as usually accessories need high amps.

Disclaimer, I am not an electrical engineer but stayed at Holiday Express last night.

[spogshd 4]

6 hours ago, aslanefe said:

Disclaimer, I am not an electrical engineer but stayed at Holiday Express last night

Lol.

The blue and green turn my fans on when the sniper asks it to, after i set the temp for each fan on the hand held

[Mach1 Driver 560]

You've  done well , but as Maxwell Smart would say: "Missed it by that much Chief". Light blue and light green from the 10 pin to relay coils 85 is correct. Pink in the 7 pin should go to wire 904 as you show. The fans can connect to relay terminal 87 which is NO (normally open). Now the problem: wire 904 is only 18 ga. and you don't want to pull an additional 20+ amps through it and smoke the wire and ignition switch- that's why you've got the relays- to separate the circuits. Connect the relay common terminals (20?) directly to the battery with some stout wire. Find out how much amperage EACH fan pulls and follow the chart for gauge and length, but notice that the chart is for 150*F which is way low, so bump it one gauge. It's hot under the hood, so don't use wire with PVC insulation- go with TXL which is good to 125*C. You can get it from Painless under accessories, bulk wire. 

BTW, use good relays like 30A Bosch. That common terminal should be #30, not 20.

  

[spogshd 4]

Mach 1, thank you, it is marked 30 its a poor photo sorry.

The amp of each fan is 8 amp so i guess 16 amp is being drawn when both fans are in the run position.

Do you know if i can access 904 from the engine bay or am i best going from the ignition switch.

[Mach1 Driver 560]

its accessible at the regulator- see the bottom of page 5: 

[aslanefe 333]

2 hours ago, spogshd said:

Mach 1, thank you, it is marked 30 its a poor photo sorry.

The amp of each fan is 8 amp so i guess 16 amp is being drawn when both fans are in the run position.

Do you know if i can access 904 from the engine bay or am i best going from the ignition switch.

Blue/red (904) is on the 3rd pin of the voltage regulator which is under the starter relay by the battery; you do not need to go  all the way to ignition switch. Put your relay in that area and get the power to relay from the battery directly and use 904 and Sniper blue and greens for signal to relay. This way your fans will turn off when ignition is turned off and come on when the car is running and Sniper turns them on. Don't forget to add fuses to power feeds to the fans.

[aslanefe 333]

After looking at Sniper wiring and another night at Holiday Inn Express, below is how you should wire.

Green or blue from Sniper to 85 on relay.

87 to fan.

30 to battery +.

Fuse between 87 and fan or between battery + to 30 ( I am not sure which one is better of if matters).

What is connected to 86 depends on how Sniper provides the signal through green and blue wires and if you want the fans to turn off  when temp goes below Sniper set temps even ignition is off or turn off when ignition is off regardless of the engine temp.

If Sniper cuts off signal to green and blue when ignition is turned off even the temp is high, you can connect 904 or battery + (via juumper from 30). In this case the fans will turn off when ignition is off.

If Sniper does not cut off signal to green and blue when ignition is off if temp is not below Sniper set temps, you have 2 options. One is cut the fans off when ignition is off even when temp is above Sniper set temps; In this case, connect 904 to 86. Second option is to let the fans run until temp is below Sniper set temp; for this case, connect battery + to 86.

Did I confuse you? Let me know if you want to know how to find out if Sniper cuts the signal to green and blue or not when ignition is turned off and I should be able to show you a way as I will be staying at Holiday Inn Express for a couple more days.

 

[smh00n 87]

The Sniper fan wire green and blue are ground wires.

You have to have clean, dedicated power and ground to a Sniper other wise they give you hassle. I would not link in anything to the power wire, nor would I take power from another source. Direct to battery for both, big fat wires.

Mine booted up immediately on install, the Holley forum is full of sob stories and most of them relate to power and interference. My fan relays have a separate power circuit and only the ground relay wires are seen by the Sniper.

 

[spogshd 4]

15 hours ago, aslanefe said:

Blue/red (904) is on the 3rd pin of the voltage regulator which is under the starter relay by the battery; you do not need to go  all the way to ignition switch. Put your relay in that area and get the power to relay from the battery directly and use 904 and Sniper blue and greens for signal to relay. This way your fans will turn off when ignition is turned off and come on when the car is running and Sniper turns them on. Don't forget to add fuses to power feeds to the fans.

So a 10 amp fuse on each fan relay

[spogshd 4]

At the moment my fans run all the time when ignition is on, so I'm happy to have them cut out once the ignition is turned off.

Mach 1 thanks for the diagram.

[aslanefe 333]

4 hours ago, spogshd said:

So a 10 amp fuse on each fan relay

Your fans should tell you the answer to how many amps they pull and what the fuse requirement for them is, then you have to figure out the gauge of wire you should use (using the wire sizing chart posted above) from battery to relay 30, relay 87 (through fuse) to fans depending on the total length of wire from battery to fans.

[Midlife 814]

A 10 amp fuse for each fan might be OK for current usage while the fan is on, but IIRC, there's a large surge current when the fan comes on.  Most electric fans require 30 or 40 amp fuses. 

[Mach1 Driver 560]

Mid is right that motors have a large inrush of current when starting, and the answers you get will vary all over the map, so I'll quote a source, which is  mgispeedware.com who published the guideline shown below for 12 VDC applications. If your motors have 8 amps at full load (which seems a little low) that would be 8 x 2.5 = 20 amp fuses each.

 

[spogshd 4]

Thanks Guys I think I've got this covered now.

I'm going to put a separate fuse block near my regulator to feed the fans, fuel pump, turn outs plus any other future accessory's .

 

C