@Wil’s Workshop Thank you!! I just finished my LS swap standalone wire harness with help from Brandan at LT1swap and Mike from ucandoit2 and was wondering how I was going to wire up the duel electric fans using B41 and R33 from the Dorman fuse/relay box. I have one question on relay pins 30 and 85 do I wire pin 85 to the battery + and pin 30 to ignition key ON fused source?
Yep, you can absolutely use leftover relays in the fuse block, I've done it a bunch of times. Just figure out which fuse and wires are used to activate the relay and wire them up to the fan triggers.
how did u figure out which wire is which on fans? what happens if you get it backwards? fan melts down or runs backwards? if u have a choice is it better to pull or push the air thru? my ac didnt work anyways so i removed all the componenerts and can mount fans front or back of rad.
DC motors generally just run backwards if you switch polarity. I just touched the wires for a second to check which way they spun. "Puller" fan setups will almost always be better in terms of efficiency. "Pusher" fans will work fine, but they need to be shrouded better and usually oversized. It mainly has to do with airflow. Behind the radiator the vehicle speed pushes the air thru the fins and the fan pulls it thru faster, but pushers partly block airflow into the radiator and have to force it thru the fins. Either can be used but I always go puller if I can.
It depends on which vehicle the PCM came from. Some vehicles had electric fans stock and will work as-is. Some had the mechanical fan and the electric fans will need to be turned on in the program.
wow man , seems pretty straight forward but also seems to exact opposite of my set of relays . ive got yellow and blue as power circuit; 30 incoming 87 outgoing power. But my wiring diagram shows the blacks as grounds! so i tested it this way and it worked . Are these relays designed to work both ways? as long as theres power going to 85 and 86 it will close the circuit? i didnt wanna push my luck and try it backwards even though the kit came with 3 extra relays. So just to be clear are you working with a1999-2002 year 411 PCM?
Yep, the relays will work both ways without problems (usually, some brand may have diodes or something in them). The numbers are just the "standardized" way to wire them. It's mainly for troubleshooting later or if someone has to fix the work 10 years later they can just go off the numbers to see what the other guy did. For that project yeah it was a 411 PCM, but the 03-06 P59 uses the same fan relay wires, so any of the 99-06 24x computers will be the same.
I usually just stick my hand in front of them, you can feel the air going one way or the other. If it's backwards, just swap the wires and it should go the other way.
I don't recall since it's been so long, but for a 30 amp fan you'll want 10ga or larger, and 60amp (for two 30 amp fans) you'll want 8ga or larger. Most modern fans are 30 amps or less per fan, but always check first. Something like the old Taurus fan is 75 amps for one fan, it WILL catch wires on fire if they're too small, just glad I had a fire extinguisher with me.
If you have a spare fuse or two the correct size you can do it thought the harness. I have a newer video on my S10 where I wired the fan power thru the OEM fuse block which has a spare 60 amp fused terminal.
If the fans run constantly it could be your temp sensor. If it's unplugged or damaged the default option in the PCM is to run the fans so there's no chance of overheating the engine since the PCM has no idea what the temperature is. If the sensor is reading the correct temp then it's likely wiring to the fans or a really low ON temperature set in the PCM.
If you're using the stock fuse block, it uses the stock fuel pump relay, the computer will prime the system then run it when the engines running. I have a video on the fuel pump wiring also. ru-vid.com/video/%D0%B2%D0%B8%D0%B4%D0%B5%D0%BE-s4wgEMFf-kg.html
Correct, the mechanical fan engine computers typically dont have the electric fan settings turned on. If you can find a place locally that does LS tuning, they can turn them on for you.
You'll need programming software if you want to do it yourself, I use HP Tuners, but there's some other ones out there. The other way is to just buy a computer tuned for a LS swap application.
The PCM has 2 fan output wires. They can be set at different temperatures to control two separate fan relays. Fan 2 is just wired to it's own relay. The PCM can turn on one at a time or both at once depending on the programming.
Stock is one fan with a low setting and one fan with a high setting, using 2 relays. The stock fan On/Off temperatures are Fan 1 - 226*/219* and Fan 2 - 235*/227*. Fan 2 almost never comes on even in a stock vehicle. This setup is identical to stock except I lowered the On/Off set-points for the fan operation, and obviously I didn't use stock 5.3L fans and relays but ones that would fit my radiator better.
