Chevy Trailblazer SS Forum banner
1 - 20 of 64 Posts

·
Registered
TrailblazerSS
Joined
·
189 Posts
Discussion Starter · #1 ·
Does anybody know what control logic the Spal brushless Vette fan uses? High or low side signal from the ECM? I know it's only 3 wires like the C6, but I don't have a diagram/manual that covers the C7.
 

·
Registered
TrailblazerSS
Joined
·
189 Posts
Discussion Starter · #2 · (Edited)
Answering my own question...

C7 brushless fan uses the PWM EV setting at 100Hz, per a stock tune from the HPT repository.

C6 (and 06-09 Ford Fusion fan that uses the same Siemens controller) uses PWM Electric at 128Hz.

The difference between the two settings is the relationship between Fan Desired % to duty cycle - they're backwards from each other. One is low% = low DC/high% = high DC, other is low% = high DC/high% = low DC.

So if you install a PWM fan and it goes backwards from what's commanded in the tune, change to the other fan type!
 

·
Registered
TrailblazerSS
Joined
·
189 Posts
Discussion Starter · #3 ·
This fan is a BEAST. Total cost was around $270 not counting misc bits I already had on hand.







(this is for a 2006/E40)


Tune must be set to PWM Electric/128Hz - the fan WILL NOT WORK with the settings from a C7 tune file (PWM EV/100Hz).
 

·
Registered
'07 3SS 2WD
Joined
·
480 Posts
Can you throw some of us a bone and provide a few more details?

Like, where the fan assembly came from for $270? Did you hack up the mechanical shroud to make it work?

How about the wiring for E67?
 

·
Registered
TrailblazerSS
Joined
·
189 Posts
Discussion Starter · #5 · (Edited)
Sure.

I got a new aftermarket 4.2L fan shroud and cut off all the sticky-uppy bits. Shroud, $20 at Rockauto.

Cut a piece of .063 3003 AL sheet to blank off the hole. Braced across the opening at the top with 2x2 AL angle. Lots of #10-32 Rivnuts. Homemade 1" OD washers and fan-to-plate mount brackets from 1/2 x 1 barstock.

Fan application: 2016 Corvette Z06 (600W), ACDELCO 15-81914, $190 at Rockauto. The Corvette shroud has the connector exit to the passenger side, to keep the wire runs short I chopped off all of the shroud except the round part and rotated it around so the connector is in the same spot as the stock EV fan connector.

8AWG GXL wire, ebay seller 'Wirebarn'.

60A J-case fuse for the 'trailer' +12v power point. (brushless fan, soft-start has no inrush spike so doesn't need to be overfused, worst-case current draw is 54A @ 11v, 42A @ 14v, 60A fuse is fine here)

Misc ring terminals/braided sleeving/heatshrink/whatever else already on hand.

----------

Wiring schematic is the same for 2007/E67, it uses the original wire that goes to the EV clutch fan. For later trucks that have the plain viscous non-electro fan use ECM C3 (X3?) pin 49.

edit: add 2007 wiring diagram

 

·
Super Moderator
TrailblazerSS
Joined
·
1,440 Posts
Info overload lol.. well they asked for it.. thats a badass setup, are you selling it or just showing off your skills?

Sent from my boujea ass phone
 

·
Registered
TrailblazerSS
Joined
·
189 Posts
Discussion Starter · #8 ·
Neither really, just showing it's possible. I haven't seen anyone use this fan in a retrofit like this before. Compared to LS1 fans it's cheaper, doesn't need a dumb expensive relay harness ($$$ if you buy it, pain in the ass to build it yourself properly), doesn't need the second wire added to the ECM for the Fan 2 relay control, only needs a single 60A fuse so it can run off the existing trailer accessory stud...

It would be difficult for someone to sell it as an affordable bolt-in kit because of the stock shroud issues and harness exit location. Using it as-is would be clunky and modifying it like I did would drive the cost up to who-knows-what. SPAL does offer a 'universal' fan of the same size with a plain round housing but it's about 3x the cost of the OEM C7 part. The SPAL aftermarkets also use a different control logic, unknown what it would take to make it work off the ECM. They do have standalone temp senders that generate the correct PWM signal to run the brushless fans, but again, big $$$ for the universal/aftermarket parts.

Mounting & wiring it was the easy part, I fought with the Fan Controls settings in HPT for like a week and a half trying to make it spin. I even tried a backup ECM thinking the fan speed driver must have been fried. Again, at least with an E40, the stock C7/E92 settings don't work. Have to use PWM Electric, 128Hz, State vs. Desired % all zeros, Output Control vs. State all 1s (same settings as the C6 fan). It also did weird shit at key-off even below the Enable temp until I gave up and disabled it. No, I don't know how it's working with the 'wrong' tune settings. :dunno:

I'm still adjusting the fan speed tables but so far I've seen it hold coolant temp steady in the 170*s with ambient at 93*, idling, in direct sunlight, A/C on max, doors open, and fan speed only in the mid-30% range.

(35% of 600W means only 15A @ 14v)
 

·
Registered
'07 3SS 2WD
Joined
·
480 Posts
Wish you woulda posted this a month ago. LOL.
 

·
Registered
'07 3SS 2WD
Joined
·
480 Posts
:throw: LOL
 

·
Registered
TrailblazerSS
Joined
·
189 Posts
Discussion Starter · #12 ·
If you want what's probably the :king1: of badass fans look for GM 84100128/ACDELCO 15-81859 (still only $258, Rockauto). Huge giant monster 850W SPAL brushless from a 2016 Camaro SS. That is a truly stupid price for that fan.

Uses the same Yazaki connector as listed above, but at 850 watts you definitely can't get away with the skinny-wired Motorcraft pigtail. It would need to be fused at 100A, might could get away with 80A.

Conveniently, the C7 Vette has an auxiliary distribution box with B+ input, 225A ALT, 80A fan & 100A EPS posts. GM 23173653, $26. The bracket it mounts in and the cover are #s 23173654 & 23491757 (~$7 each).



You'd possibly (probably?) be needing an alternator upgrade as well. And, it's hidden in the split loom, but there is a fusible link on the alt output to the battery that would need to be bypassed, and if you're doing that you should just run a new fatter wire to handle everything. The Corvette distribution box is an easy way to handle all the new stuff and still have the alt fused.
 

·
Registered
'07 3SS 2WD
Joined
·
480 Posts
Are the dimensions of this fan/shroud listed anywhere you know of? I can't seem to find them, other than the 19.32 IN on RA.
I plan on towing with my TB on occasion. I won't be towing all that heavy, but it will almost always be in our wonderful summer temps. Seeing the older style Camaro fans, they seem kind of anemic for that task.

The two setups you have in this thread seem better suited for this job.

I put dual Taurus SVO fans on my DMAX. Those things pull some huge air, but I'd like to stay PMW with the TB.

I can get cheap Waytek fuse blocks through work too. $10 for the holder and 100A fuse.
 

·
Registered
TrailblazerSS
Joined
·
189 Posts
Discussion Starter · #15 ·
Yes, but you need more than just the fuse and the Vette block makes the other stuff you need to change much easier.

No dimensions I have found on the Camaro shroud, but the radiator core dimensions can give a general clue.
Camaro: 20.8"H x 22.6"W
TBSS: 18.1"H x 27"W
 

·
Registered
'07 3SS 2WD
Joined
·
480 Posts
The Vette block is OK. There are cheaper/better options out there. I needed a high amp power block for a machine at work (I work for an OEM equipment manufacturer, UHP waterblasting, class 8 trucks, FAA, type of fun), and found one with a cover for something like $20. I'll try to remember to grab the link on Monday. Similar to the Vette piece(4 post), with all the extras, for half of the price. Comes in red and black. Be great for big stereo guys.. Not it, but similar. Quick search here says the TB alternator is 145a. Should be sufficient for the task. My DMAX came with a single 105a. I upgraded to dual 145 later.

Camaro radiator is almost 2.75" taller. It must be in there at a pretty steep angle. It has a lower valance, but the overall real estate just seems less.
 

·
Registered
TrailblazerSS
Joined
·
189 Posts
Discussion Starter · #17 ·
Try this. Idle your truck with all the accessories on, AC on, headlamps on HI, etc. Let it run 30 minutes. Hit the alternator charge wire, battery positive post, & the input post to the I/P BATT fuse on the front of the fuse box with an infrared thermometer (or just touch them, if you're feeling brave). The heat at those spots will make you think twice about adding big electrical loads without significantly beefing up the stock wiring. The crimp connections are unsealed and by now they've been exposed to everything for 12+ years. They're crusty inside, guaranteed. Mine were and my truck has lived in GA/MS all its life.

The ALT charge wire to BAT is 19mm2 (~5AWG equiv.) but at the fusible link it necks down to only 8mm2 (~9AWG). Besides the limit that places on ultimate alt output capacity if upgraded, even with the stock alt at just 145A a smaller cross section wire means greater voltage drop which equals heat, and heat results in even greater voltage drop, which results in... you get the picture. All the BAT & GND wiring on these trucks need upsizing or adding new, second wires jumpered between their connection points. Leave the stock ALT wire in place, stack a new 4AWG wire onto the ALT output post and run to the I/P BATT fuse input post, etc. A ~300A fuse here would be nice just for peace of mind.

Or, in your case, run the new additional ALT wire to the input of your new fuse block, then a second stacked wire from the fuse input over to the I/P BATT fuse input. The stock ALT wiring is for sure not up to the task with the bigger 850W fan.

The alternator directly powers the loads, after starting the battery is only there to be topped up for the next start. If the system is designed right and in good order, that is. All of the current goes down the ALT wire, into the crimped bundle (probably crusty by now) in the POS battery terminal, and out to the I/P BATT fuse (fuse input powers the front PDC, fuse output powers the rear PDC).



 

·
Registered
'07 3SS 2WD
Joined
·
480 Posts
Thanks. RockAuto has good pics too.
 
1 - 20 of 64 Posts
Top