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Hardhead
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Discussion Starter #1
I'm trying to get my act together and make a set of relays to run my Intrepid fans. These are just the standard fans, no relays on the shroud. I intend to have the 0411 PCM run these also. I've read that if I use thermostatic switches in the water jacket of the heads they tend to fail and I don't want the hassle, that's why I want the PCM controlling them. I don't know a lot about wiring or relays so I have some questions. I'm under the impression that pin 86 on the relay is where 12v Ignition is attached and pin 85 will be ground. Pin 85 is inserted into the Blue connector (C-1) at location 42. This should be the Low Speed fan trigger. Pin location 33 on the Red connector is where the trigger for High Speed is located. Now for a question. Note: I will NOT be running a/c.

1) Are the 12v ignition wires at pin 86 of the relays required to be seperate or can they be jumped at pin 30?

2) Can I tap 12v voltage at the 175 amp main fuse for the required voltage to drive the fans when operating?

3) Is a 10 amp fuse sufficient on each of the 86 terminals going to the relays? I will wire these with 18 guage wire.

4) Is a 30 amp fuse sufficient for the main power going to the fans or should I go with something bigger? The wire going to the fans will be 10 guage.

I'll try to get a schematic posted when I get it drawn up.
 

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Been there Done it
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8,187 Posts
Had this typed up 12 hours ago and forgot to hit post. Duh!
You can connect the 2 hots together, but usually 30 is direct from the battery and 86 is switched ignition.
Don't see why you couldn't use the mega fuse contacts for the fan power. I bought posts for the battery cables that have a bolt in the center ($11/pair) to connect directly to the battery because my controller manufacturer was adamant about connecting "directly to the battery". Fuse and wire size sounds fine. I've got 30's on my fans w/o issue. Intrepid fans aren't like Taurus fans that use huge amperage. Theoretically more amps means more power, but the Taurus is an older design and I'd bet there more loss. My controller is soft start so there are no spikes. I read somewhere online the GM is also soft start.


338612

After seeing the drawing I'd make 2 changes to suit my taste. One is to use an ignition source for the 86's so that the fans stop when you turn off the key so if there is any issue with the PCM or relays the battery won't go dead. I'd also put a 30 amp on each fan so that if one motor was to short out or bind up you could still run the other.
 

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Hardhead
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869 Posts
Discussion Starter #4
Had this typed up 12 hours ago and forgot to hit post. Duh!
You can connect the 2 hots together, but usually 30 is direct from the battery and 86 is switched ignition.
Don't see why you couldn't use the mega fuse contacts for the fan power. I bought posts for the battery cables that have a bolt in the center ($11/pair) to connect directly to the battery because my controller manufacturer was adamant about connecting "directly to the battery". Fuse and wire size sounds fine. I've got 30's on my fans w/o issue. Intrepid fans aren't like Taurus fans that use huge amperage. Theoretically more amps means more power, but the Taurus is an older design and I'd bet there more loss. My controller is soft start so there are no spikes. I read somewhere online the GM is also soft start.


View attachment 338612
After seeing the drawing I'd make 2 changes to suit my taste. One is to use an ignition source for the 86's so that the fans stop when you turn off the key so if there is any issue with the PCM or relays the battery won't go dead. I'd also put a 30 amp on each fan so that if one motor was to short out or bind up you could still run the other.
If I used a ignition source for the 86 leads, would it cancel out the ability of the PCM to run the fans after shut down?

The way I routed my fan leads is what got me to thinking about using the MEGA fuse terminal. There are body grounds right there also. That leads to a nice clean, compact installation site. It also gives me ready access to the PCM. Where would there be a good spot to pick up access to an 12v ignition source if I went that route?

Just for clarification, what do you mean that you have 30s on your fans without issues? You lost me. Do you mean 30 amp fuses or relays?
 

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Been there Done it
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8,187 Posts
I didn't realize the PCM would run the fans after shut down. That would cool the rad but w/o the water pump running the cooler water would not enter the engine. I've seen vehicles setup to do that, but never understood why.
I'm sure the mega fuse connection will work OK. Just a PITA to get at.
I used 30 amp fuses and relays. One of each for each fan. Fan is actually out of a 2000 Chrysler 300M.

I'm using a Delta Current Controls FK-45. You set the water temp you want and forget it. It runs both fans all the time at whatever speed it needs to maintain the temperature. There is an LED on the dash that varies from green to red depending on how fast they're going. All the guys at Pirate 4x4 use them in there off road buggies w/o any problems. So you know they can take a beating and keep on working.
Most of the others like BE Cool, Spal, Flex-a-lite, Derale, use off shore made controllers and few last a year with gentle use.
DCC's are made here in small batches and the company owner is an electrical engineer. They can take a while to get depending on his production schedule. Not cheap, but not much more than the Chinese ones sold
by the brand names that don't last. Only drawback is there is no mph cut off.
 

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Registered
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1,634 Posts
The PCM uses a ground trigger, so the ignition to 86 will work fine and you want 12V to that side of the coil anyway.

The run on time can be set in the PCM. I originally had the fans setup to run after, but like @oldeerslayer mentioned there isn't much advantage and didn't want to run down my battery either.

This schematic is from a Camaro, but it's the same concept with any 0411/P59.

338636
 

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Hardhead
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869 Posts
Discussion Starter #7 (Edited)
An electrical guru I'm not. Where are some 12v ignition sources I could possibly tap?I was thinking (which I know is dangerous) that maybe tapping into the DRL system since it's up front? Just a thought.

Sounds like there isn't any advantage to keeping the feature where the fans run after the vehicle is shut off. Makes sense but I wonder why the factory does it then?

I'll go ahead and split those power leads to the fan and fuse them seperately also. Thanks for that suggestion. Never thought of that. The battery posts look like they're worth looking at too to keep the wiring more accessible.
 

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time to get cereal
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2,628 Posts
Backup lamp fuse is the easiest ignition power to get to that I know of. That's if yours is a 98+.
 
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