So I recently acquired a 2000 Tahoe the previous owner was in the middle of swapping out the motor driven radiator fan for dual electronic fans from a newer model silverado. I was helping in the swap as the vehicle became mine midway thorough the conversion. At first you would need to plug the fans in under the hood after starting the car and unplug after turning it off. We finally got around to wiring them up to a toggle switch however when doing so we wired one connection to an ignition fuse under the steering wheel. After wiring everything up we took it on a test drive and after a few minutes on the road the gauge cluster cut off it was receiving no power but the truck was still running. After we brought it back we unplugged the wire from the fuse, which was still intact. But now it will not start and we can not figure out why when you turn the key it does not even try to turn over there is no signal getting to the engine telling it to start has anyone had a problem like this doesnt have to be the same cause as mine but if you have had electrical problems that sounded like this I would love to hear how you went about figuring out what the problem was or how it got fixed please it is very urgent Im about to start work and need a vehicle we spent forever getting the transmission back in working order only for this to happen and it has us scratching our heads we dont even know where to start
Electric Fan swap causing problems
- Thread starter Tarzann
- Start date
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You are going to need to take a meter and test out lots of wiring and fuses, to see where you do and do not have power. Most likely you guys damaged a ground strap when installing the eFans, but the link between the alternator and the battery is known to rot over time as well; a good bump against a rotten wire will take it out of service.
Alternately you'll want to get it to a mechanic so he/she can do the tracing -- and it won't be cheap.
Alternately you'll want to get it to a mechanic so he/she can do the tracing -- and it won't be cheap.
drakon543
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did you connect power for the fans directly to said wiring/fuse or did you run it through a relay to run the fans. have you checked the fuses yet or just assumed it was still good as the truck was still running? electric fans draw a decent amount of power so using an ignition source to trigger a relay is a good option for constant on fans. trying to draw the entire power feed through that source is a bad idea as you are potentially drawing high amount of amps through a system not designed to do it. first thing to do is just check all fuses first. well maybe not all but instead of figuring out which ones are part of that ignition source and checking fuses is easy just check them all.
The Fans draw serious power. You have to run relays under the hood, to power the fans. And the hot wire that is being fed to the contacts of those relays has to come directly from the battery, or alternator (preferably with a big fuse in-line). Learnings from having done this conversion on a truck: 1) You need a high output alternator, 2) You likely may need a smaller pulley on your high output alternator, 3) You can't start both fans on high at once, the voltage will dip badly. Low speed first, delay, then high speed.
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corvette744
2004 Z-71
Agree check all fuses prob blew one.All meaning big fuse's and small ones under hood and dash board.Let us know from their.
Good luck with this, like others said the fans can draw 100 amps so I’m hoping you used relays and wired them with their own fuses. The best way to accomplish this job is to use a factory harness with its own relay pack and have the pin on the ECM turned on so the computer can control the fans or use an aftermarket harness which can use the ECM or a thermostat. I’m guessing you either blew a large fuse or -hopefully not- burned a wire.
corvette744
2004 Z-71
Must not of been to urgent or he fixed it no reply in a month.
Please provide a photo of said "ignition fuse under the steering wheel" or where you had it connected because there isn't one, at least not under the steering wheel.
It was a drive-by posting!
I absolutely hate the newbs that join just because they have a problem, then come on here and post once or twice and then disappear with no update on whether it got resolved. Waste of time. 
that is why i suggest a smoothing capacitor inline with the fans, the voltage will not dip at all.. or get alternator from a rig that has electrical fans
Flash1976
TYF Newbie
I swapped out my dual electric back to belt drive fan clutch system due to power supply reliability issues. Randomly blowing the power supply to the fan in pretty dangerous to overheating, particularly in the normal 118 F days out here in the summer. I choose reliability.
What were you using for a fan harness? The aftermarket ones tend to melt the wires or relay packs. I finally bought an OEM harness off a wrecked truck from @ScottyBoy who cleans them up and relooms them. No more issues.
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Mudsport96
Full Access Member
I build my own stuff for the most part. Didnt need to do fans since mine is factory efan. But, on my old 1995 f150 there is a headlight kit to take the full load off of the headlight switch and move it to a relay pack. With the advanced age of these older trucks the voltage drop is measurable at the headlight sockets. Mine was bad enough that the left light was getting 10v running and right was 11v when the charging volts were 14.5
Different places use anywhere from 14 to 18 gauge wire and your typical cheap relays ( one for lows and one for highs). Looked one over and built my own. Used 10 gauge wire and 4 relays one for each low beam and one for each high. Overkill? Maybe but i dont have issues with melting either.
Flash1976
TYF Newbie
I switched to electric fans on my 2003 6.0 Yukon, but swapped back due to unreliable power supply relay issues. It just was not worth the risk. The system I had used a single power supply relay for two fans. A better system would have independent power systems for each fan, that way if power failed on one, you at least had a back-up. For this reason, I never converted to an electric fan system on my 2000 5.3 Tahoe. I changed out radiators for both to (4) row systems, and added 10,000 GVW tranny coolers. Towing up to Lake Havasu or Big Bear is either very hot (120 +) or very steep (12% grade @ 5000 ft +) so extra cooling is a must.
Midnight mechanic
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Sounds like you blew a **** fuse one of the 40amp ign fuses
I finally got tired of trying different options and bought a controller from Auto Cool Guy (www.autocoolguy.com). I haven't had a problem for a long time. A little bit of cost for piece of mind.
Just use an OEM fan harness with the relay/fuse assembly from a wrecking yard or EBay and be done with it. Then you have the exact same setup as the newer trucks have. I had nothing but trouble with a harness and relay setup I bought from LS1fans.com , melted it then rebuilt it with heavier wire and 80 amp relay blocks and it started showing signs of overheating again. Put the OEM one in and voila. I bought mine from a member here @ScottyBoy, not sure if he’s still selling them.
ScottyBoy
Full Access Member
I've known a few people who had issues with the harnesses from LS1fans, and heard about countless others who had issues. For some reason, those harnesses just can't seem to handle the max current draw that these fans will pull, and they end up melting the wiring, the relays, or both. And yes, I still sell refurbished OEM harnesses, I currently have two of them in stock at the moment I'm typing this.
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