The fans run on low speed all the time and kick to high with A/C. Not sure if that’s how it’s supposed to be but that’s how mine are.
2000 GMC Yukon XL K2500 6.0/4L80e/3.73s/BlackBear tune
2014 Aerolite 282DBHS TT
Electric fans enough for 3/4 ton XL that tows?
- Thread starter bfourman
- Start date
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The fans run on low speed all the time and kick to high with A/C. Not sure if that’s how it’s supposed to be but that’s how mine are.
2000 GMC Yukon XL K2500 6.0/4L80e/3.73s/BlackBear tune
2014 Aerolite 282DBHS TT
bottomline2000
Full Access Member
Ok, I had a feeling you would say that. There seems to be an issue with some early 00 PCMs that cause the constant fan on condition. Mine did the same and I was cooking relays like crazy. I had to switch to a 0411 PCM which is a newer operating system. I bought mine on ebay from an 02 escalade.
It took over a year working with Justin at BB and a lotta parts to figure this out. He programed the new pcm and all has been well since and that has been over 5 years ago.
Your fans should not turn on automatically when you start your truck unless your ac is on and even then only the passenger fan should come on.
Ironically I now run a 6.0/4l80 with the same pcm, but I do have an issue with lockup in my converter because Justin had to do a segment swap to operate the new trans but it won't stay locked with 0%throttle input. If he his able to swap pcms for you and keep your Trans settings maybe I can get my issue resolved too...win..win.
hope this helps as I seemed to be one of a few with this fan issue.
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Hmm ok. Thanks for the info, I’ll get with Justin and see what we can work out. I have a handful of spare relays but I would hate for the fans to stop working while my wife is driving it.
2000 GMC Yukon XL K2500 6.0/4L80e/3.73s/BlackBear tune
2014 Aerolite 282DBHS TT
bottomline2000
Full Access Member
If you don't use the a.c. they will just run on low which wasn't a problem. The truck will run a lil cool so economy may drop a little. It was a nightmare with my wife and trying to explain it. It was easier to keep her out of it, but at least you know to watch it.
Keep us posted as I'm curious to see if Justin can just swap your programming to a newer pcm and everything work as normal.
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Good point, if I have to I'll pull the A/C relay until we can get this resolved. Luckily Indiana doesn't look to be leaving winter any time soon.
I emailed Justin and will post updates. If there is a way to tag him in this post, someone with more forum knowledge can do so.
Update. Justin sent me a 'new' PCM with the updated 2002 software for the fans. I also had him adjust a few things that have needed done for a while now to silence the SES light.
Driveway testing proved successful. I haven't driven it yet but the wife is as we speak and she says its fine. Hoping to put the camper behind it in the next couple weeks and see how it does.
Last weekend I towed the camper with the 'old' PCM and everything was fine, minus no A/C. Ambient temp was in the 70s and engine temp never got over 200*. Of course this was with the fans on low all the time.
Driveway testing proved successful. I haven't driven it yet but the wife is as we speak and she says its fine. Hoping to put the camper behind it in the next couple weeks and see how it does.
Last weekend I towed the camper with the 'old' PCM and everything was fine, minus no A/C. Ambient temp was in the 70s and engine temp never got over 200*. Of course this was with the fans on low all the time.
Another update. Towed the camper last weekend with zero problems. Temp never got above 211*, and that was after a decent hill pull at 30 MPH coming out of a small town. Ambient temp was in the 80s. Aircon was excellent all weekend, its nice having ice cold air at idle.
I don't know what Justin did different, but this tune seems to have more pep than before. Maybe because I specified 93 octane vs 89 last time? Either way I picked up 1 MPG empty and it runs strong right out of the gate.
Bottom line I suppose is that if you have a 3/4 ton GMT800 6.0L with a clutch fan the e-fan upgrade will work and work well, even while towing.
I don't know what Justin did different, but this tune seems to have more pep than before. Maybe because I specified 93 octane vs 89 last time? Either way I picked up 1 MPG empty and it runs strong right out of the gate.
Bottom line I suppose is that if you have a 3/4 ton GMT800 6.0L with a clutch fan the e-fan upgrade will work and work well, even while towing.
That's great to know, Byron. I have an identical truck and I've debated going to an E-fan. My family and I are thinking of getting another camper next year and I want to prep the Yukon for it beforehand.
How are the 3.73's with towing that camper? I looked up the specs on it because that's similar to what we want and it's dry weight is around 6000#'s. Load some gear in there along with 4 kids, my wife, and the dog....I'm tipping the scale close to my max towing capacity of 7600#'s with the 3.73's. I was debating throwing 4.10's in it as well so I won't have to worry about it. What are your thoughts on that?
swathdiver
Full Access Member
Bingo!
It works fine. 4.10s would be better of course but it’s not awful. We haul around 4 kids and all their stuff in this camper without too much effort. Just remember the 6.0 makes it’s power higher in the rpm range and don’t be afraid to run it at 3k all day.
Our previous camper weighed in around 8500lbs loaded and the Yukon struggled a bit with that but still managed.
I’m still on the lookout for a full float 14 bolt with a govlock and 4.10s but for now I’m happy. Right now we average 15 mpg mixed city/hwy empty and 8-10 towing depending on whether the camper or Jeep trailer is hooked up.
For reference, the 09 Sunnybrook (heavy SOB):
2000 GMC Yukon XL K2500 6.0/4L80e/3.73s/BlackBear tune
2014 Aerolite 282DBHS TT
