December 16, 2019, 05:04:22 AM

Author Topic: Two speed Taurus fan wiring (GM PCM)  (Read 17890 times)

Offline RX7V8Builder

Two speed Taurus fan wiring (GM PCM)
« on: May 29, 2010, 09:14:57 AM »
This is related to what PEZ wrote in a thread related to the TAURUS fan install in General Tech:
Hope you dont mind the quote.

Quote
The Taurus fan is designed for a low/high operation.  Feed one power wire (don't know the colors off the top of my head) and you get low, feed the other power wire and you get high.  That all works great, when it's controlled by the FORD PCM, but not the GM PCM.

See, when the Ford PCM wants low, it grounds the low fan relay coil and for high it removes the ground on the low relay and puts the ground on the high coil. But when the GM PCM triggers the low fan, it sends a ground to the low fan relay coil.  When it goes to high fan, it ADDS a ground to the high fan relay coil while leaving the ground on the low fan coil.  So, this means both relays are actuated AND both low and high fan motor coils are engauged.

This essentially makes the low and high fan motors work against each other and you got more of a 'medium' speed.  Probably isn't good for the fan motors either.
Here's the fix.  Run the low relay control through a relay BEFORE it goes to the low fan relay.  This second relay needs to be spliced into the the high relay control wire so that the low relay control wire is interrupted when the high fan relay control comes on.
« Last Edit: May 29, 2010, 09:22:49 AM by RX7V8Builder »

'87 Base Model FC
LT1 385 LE ported DART heads_ T56 
8.8 IRS
Ricardo

Offline halfspec

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Re: Two speed Taurus fan wiring (GM PCM)
« Reply #1 on: May 29, 2010, 11:50:12 AM »
Well done. I drew up the same diagram at home and was going to eventually post it, but yours is better as it's actually done with spice/cad and mine was hand drawn :)

Might be worth mentioning in this thread that the relays for this circuit should be able to handle at least 40A.

Lane

Offline RX7V8Builder

Re: Two speed Taurus fan wiring (GM PCM)
« Reply #2 on: May 29, 2010, 12:06:18 PM »
You are right.  the relays must be able to handle at least 40 Amps and must be SPDT also. 
I chose  these Flosser relays capable of handling 70/60 Amps.
« Last Edit: May 29, 2010, 12:28:20 PM by RX7V8Builder »

'87 Base Model FC
LT1 385 LE ported DART heads_ T56 
8.8 IRS
Ricardo

Offline digitalsolo

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Re: Two speed Taurus fan wiring (GM PCM)
« Reply #3 on: May 29, 2010, 12:52:14 PM »
Nice post, thanks!
Blake MF'ing McBride
1988 Mazda RX7 - Turbo LS1/T56/ProEFI/8.8/Not Slow...   sold.
1965 Mustang Coupe - TT Coyote, TR6060, modern brakes/suspension...  project car
2016 BMW 428i xDrive Gran Coupe - Completely stock...ish

Offline bikedad

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Re: Two speed Taurus fan wiring (GM PCM)
« Reply #4 on: May 29, 2010, 12:54:28 PM »
I went with this setup from http://www.hollisterroad.com/ for my 95 Taurus 2 speed fan.

Just throwing another option out.

I purchased the kit with the 180 and 195 sensors.
Was very simple to install. The wires are very heavy gauge (10 Gauge off the 3 heavy duty relays)
I ordered a Painless 3 wire connector at the fan plug in to make it weather proof and easily maintainable.

On my setup the low speed fan comes on at 180 (20 amp draw) if needed it then steps up to high speed at 195 but with a low start draw because the fan is already spinning. (low speed shuts off) Typically would be in the 40 to 50 amp range depending on the age of your fan motor.
When it drops to 180 then the high speed shuts off and low starts etc..

I received a bad 180 sensor when I purchased the kit. It was easily bypassed until I could determine what was happening. I emailed him that I didn't think it was working as described and left my cell phone number. He called me the next day (and also gave me his number) and had me do a simple ground test with the fan to verify that the motor was indeed working correctly. He said it was a bad sensor and he overnighted me a new one. (great support

I went with this setup because they got great reviews and I'm not a wiring expert. I probably could have made one similar/cheaper after seeing it but the amount of time I would have spent figuring it out would have out weighed the cost. (in my opinion)

FYI,  This setup will work with LS series motors and PCM's

Couple of pics of setup.







Don Teifke  :drive:
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Offline ImprovedRacing

Re: Two speed Taurus fan wiring (GM PCM)
« Reply #5 on: June 01, 2010, 01:42:23 AM »
You are right.  the relays must be able to handle at least 40 Amps and must be SPDT also. 
I chose  these Flosser relays capable of handling 70/60 Amps.

Where did you purchase those relays? I'm having a hard time finding a high-power SPDT relay. I was going to use two SPST relays and the air pump relay to interrupt the low fan signal, but it would be nice to eliminate the extra relay.
Michael


Improved Racing Products
Tel (407) 705-3054

Offline RX7V8Builder

Re: Two speed Taurus fan wiring (GM PCM)
« Reply #6 on: June 01, 2010, 02:02:29 PM »
You are right.  the relays must be able to handle at least 40 Amps and must be SPDT also. 
I chose  these Flosser relays capable of handling 70/60 Amps.

Where did you purchase those relays? I'm having a hard time finding a high-power SPDT relay. I was going to use two SPST relays and the air pump relay to interrupt the low fan signal, but it would be nice to eliminate the extra relay.

I dont know if you can find the Flosser Brand in the US, but here is the very same product carried by Allied Electronics

Its the AZ 979-1C-12D Automotive relay

http://www.alliedelec.com/search/productdetail.aspx?SKU=6860277
« Last Edit: June 01, 2010, 02:19:01 PM by RX7V8Builder »

'87 Base Model FC
LT1 385 LE ported DART heads_ T56 
8.8 IRS
Ricardo

Offline ImprovedRacing

Re: Two speed Taurus fan wiring (GM PCM)
« Reply #7 on: June 01, 2010, 03:14:39 PM »
Awesome, just purchased a couple. Thanks!
Michael


Improved Racing Products
Tel (407) 705-3054

Offline TheSocio

Re: Two speed Taurus fan wiring (GM PCM)
« Reply #8 on: June 05, 2010, 01:54:52 PM »
hey guys im kinda of a retard when it comes to reading squematics....can someone please post a simpler diagram like the one Pez has for his AC intallation ( indicating how to hookup up the relays)

Offline digitalsolo

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Re: Two speed Taurus fan wiring (GM PCM)
« Reply #9 on: June 05, 2010, 08:03:41 PM »
hey guys im kinda of a retard when it comes to reading squematics....can someone please post a simpler diagram like the one Pez has for his AC intallation ( indicating how to hookup up the relays)

How's this?



edit:   Tweaked slightly to mirror the +12 IGN addition in RX7V8Builder's drawing up top.
« Last Edit: June 08, 2010, 01:06:02 PM by digitalsolo »
Blake MF'ing McBride
1988 Mazda RX7 - Turbo LS1/T56/ProEFI/8.8/Not Slow...   sold.
1965 Mustang Coupe - TT Coyote, TR6060, modern brakes/suspension...  project car
2016 BMW 428i xDrive Gran Coupe - Completely stock...ish

Offline bikedad

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Re: Two speed Taurus fan wiring (GM PCM)
« Reply #10 on: June 05, 2010, 11:12:40 PM »
Nice Blake.
I should have asked for that schematic before I spent $100 on my setup.

Doh!
Don Teifke  :drive:
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Offline digitalsolo

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Re: Two speed Taurus fan wiring (GM PCM)
« Reply #11 on: June 06, 2010, 09:09:47 PM »
LOL, as long as your setup works, that's what matters.

You don't have a PCM to control it anyway, do you ?
Blake MF'ing McBride
1988 Mazda RX7 - Turbo LS1/T56/ProEFI/8.8/Not Slow...   sold.
1965 Mustang Coupe - TT Coyote, TR6060, modern brakes/suspension...  project car
2016 BMW 428i xDrive Gran Coupe - Completely stock...ish

Offline bikedad

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Re: Two speed Taurus fan wiring (GM PCM)
« Reply #12 on: June 06, 2010, 11:27:15 PM »
No. not a PCM
My fan is controlled buy 2 thermostatic switches. 180 degree and 195 degree.
I also hard wired the high speed to a manual switch for when I just want to cool the motor while stopped.
Don Teifke  :drive:
[smg id=8489]
"Life is tough.,, Life is even tougher if you're stupid."
-----John Wayne-----

Offline TheSocio

Re: Two speed Taurus fan wiring (GM PCM)
« Reply #13 on: June 07, 2010, 03:05:05 PM »
thats just what i needed, thanks

Offline Pez

Re: Two speed Taurus fan wiring (GM PCM)
« Reply #14 on: June 07, 2010, 05:41:21 PM »
Don, why do you have an inline fuse when you're getting power from the fuse box?  I just use a 3/16 slide-on terminal lug and use the unused fuse position on the stock fuse box.
FC/FD plug and play wiring harnesses, LSx swap AC systems, LSx swap power steering lines.