Another TB running warm when towing (fan override switch - with pics) - Page 2 - Chevy TrailBlazer, TrailBlazer SS and GMC Envoy Forum



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Go Back   Chevy TrailBlazer, TrailBlazer SS and GMC Envoy Forum > 2002 - 2009 TrailBlazer/Envoy Tech > 02-09 General Tech Q&A > Towing

Towing Towing with your TrailVoy

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  #11  
Old 10-05-2009, 04:01 PM
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Quote:
Originally Posted by ScarabEpic22 View Post

I would strongly suggest changing your trans cooler to be after the factory one, the factory "cooler" is more of a heater and then the aux cooler brings the fluid down in temp. Up to you though.

.
Depends on where you live... I do them like he did, so that the radiator can still heat up the transmission when it's cold out, rather than heating up the trans fluid, then cooling it back off in the aftermarket cooler, before heading back to the trans... Works well in the summer, too, because the radiator is rarely over 200F, so it gets it up to 160-180 quicker, but doesn't really hurt anything when the trans is already heated up... If you've got it after the factory cooler, the rad puts a little bit of much-needed heat into the fluid in the winter, then the aux cooler knocks it back down... Delays transmission warm-up a lot more in the winter...

For him, though, living in AZ, I'd suggest switching it, too... No real winter to speak of, and LOTS of HOT DRY summer to worry about...

Mike
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  #12  
Old 10-05-2009, 07:13 PM
Nuttyskier2002 Nuttyskier2002 is offline
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Fantastic report! Thanks! I've been meaning to make a PWM controller to do a similar thing, but if connecting straight DC to the fan clutch input works OK (and didn't burn out the receiving circuit) then I'm going to go clip one in. You just applied 12V? With or without a current limiting resistor? I loaned my scope to my son-in-law out of town, so I can't see the real waveform.

Yes, just straight 12vdc. I tapped off of the heavy gauge red cable feeding the fuse/relay box under the hood on the driver's side. I put an inline fuse holder and feed the switch with that. Then off the other side of the switch I fed into the white wire going to the fan clutch. The fan clutch is normally feed through a relay which is controlled by the PCM. The fan clutch relay is located in this same fuse/relay box so if you are real anal about adding extra wires under the hood you can make it look really neat if you are willing to dig into that harness to find the white wire. I just went straight to the fan. It was easier that way.
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  #13  
Old 10-21-2009, 03:18 PM
Nuttyskier2002 Nuttyskier2002 is offline
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Here's another update of my latest towing experience. I towed my 20' Malibu ski boat to Lake Roosevelt over the weekend. Trip started about noon time on Friday from Maricopa, AZ where I live. It's about 130 mile each way with at least four 7% uphill grades lasting 3+ miles each. The temp was 98*. The boat and my TB were loaded with gear. On everyone of the uphill grades my coolant temp would rise to 220*. That was my limit that I told myself when I'd turn the coolant fan on to 100%. One time without paying close attention I let it get to 225* (Scangauge reading). Within 2-3 seconds of turning the fan switch on I could hear the fan start to whirl and almost immediately the temp would start to fall. It took about 2 minutes and the temp was under 200. This would happen even when still climbing one of the 7% uphill grades.

Before the modification I was strongly considering buying a cowl induction hood to be modified for heat extraction. But now I am much less concerned and feel it not to be needed.
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  #14  
Old 10-21-2009, 04:28 PM
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vewy vewy intewesting... You're sure you've got the latest fan calibration??

Mike
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  #15  
Old 10-21-2009, 04:56 PM
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I agree it's interesting. I don't recall seeing the fan calibration table in earlier versions of EFI Live, but I just checked my latest update, and it's there.

And the commanded speeds look quite suboptimal. Let me go fiddle with these before going to the desert this weekend and I'll see what happens.



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  #16  
Old 10-21-2009, 04:57 PM
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I assume that's in DEG-C, correct?

Mike
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  #17  
Old 10-21-2009, 05:04 PM
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Yes, and I thought I had it configured (earlier version) to only show me Imperial units.



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  #18  
Old 10-21-2009, 07:38 PM
Nuttyskier2002 Nuttyskier2002 is offline
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Quote:
Originally Posted by the roadie View Post
I agree it's interesting. I don't recall seeing the fan calibration table in earlier versions of EFI Live, but I just checked my latest update, and it's there.

And the commanded speeds look quite suboptimal. Let me go fiddle with these before going to the desert this weekend and I'll see what happens.
My service manual says the fan is commanded on at 100% at ~260 deg. F. 121* C = 242* F. So has the coolant fan table been updated since '03? I don't know if my PCM has ever been updated with new programming. Even if it has been 242 is too high for my comfort zone.
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  #19  
Old 10-21-2009, 08:12 PM
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Originally Posted by Nuttyskier2002 View Post
My service manual says the fan is commanded on at 100% at ~260 deg. F. 121* C = 242* F.
The service manual could be right - it just doesn't address the LOWEST temp at which the fan is commanded on 100%.

I agree - I don't like those numbers. I want a cool engine, I don't care about noise, I don't care about losing 2-5 HP. If it's hot, and in the desert it's often hot, I want my airflow!



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  #20  
Old 10-21-2009, 11:47 PM
prestonpsc prestonpsc is offline
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Originally Posted by Nuttyskier2002 View Post
Yes, just straight 12vdc. I tapped off of the heavy gauge red cable feeding the fuse/relay box under the hood on the driver's side. I put an inline fuse holder and feed the switch with that. Then off the other side of the switch I fed into the white wire going to the fan clutch. The fan clutch is normally feed through a relay which is controlled by the PCM. The fan clutch relay is located in this same fuse/relay box so if you are real anal about adding extra wires under the hood you can make it look really neat if you are willing to dig into that harness to find the white wire. I just went straight to the fan. It was easier that way.
Would you mind posting a couple photo's of this? Your wiring and where you placed the your switch?
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