FastKat

iTrader: (10)

I was looking at some schematics for a 2002 truck, and noticed that there were no provisions for electric fans.

Can the 2002 and older truck PCM + harness be setup to run hi speed and low speed fans? Will the fans have full functionality, such as turning on the A/C, turning off on highway, etc?

Are there any disadvantages to running the red-blue truck harnesses (? to 2004) over the blue-green truck harnesses? (05-06 I think)

t72ss402

iTrader: (10)

Yes you can.

Pin 42 - empty - Fan 1 Control - This will be empty on 99-2002 harnesses. A pin can be added for electric fan control. Programming will enable the fan control. PCM supplies a GROUND to turn on a relay. If you have two fans, keep reading, pin for fan 2 will be on the RED connector C2. You must wire your fans through a relay.

Pin 33 - Dk Green - Fan 2 Control - some 99-02 harnesses will have a pin here, this was used for the HVAC Recirculation Door control. The PCM would control the A/C recirculation to help cool the a/c system if it got too hot. In an engine swap, programming can be changed to let this control a second cooling fan. Again, PCM supplies a GROUND to run on a relay. You must wire your fans through a relay.

Got this info from www.lt1swap.com.

Tim.

FastKat

iTrader: (10)

Has anyone here actually done it successfully?

It seems like my options are 1) buy an 2005-2006 harness and have someone program in the single-wire A/C request, or 2) buy a 2002 harness and have someone program in the electric fans.

Is there any year/vehicle truck that has both single-wire A/C request (not serial-bus) and electric fans?

Also, any benefits of red-green vs. blue-green harness and PCM?

TurboS10

iTrader: (12)

Trucks never came from factory with electric fan.

FastKat

iTrader: (10)

I am pretty sure they did - I feel like I've seen them in trucks at the junkyard. On the one I remember seeing, the cooling fan relays were housed in a small fuse box separate from the main fuse box.

Plus, I just dug up a cooling fan diagram from ARRC for a 2006 Silverado 1500 4.8L.

garys 68

iTrader: (1)

I'm running an 02 411 ecu with both fan controls programmed. Works ok on mine, but ended up only using 1 fan.
Dont bother trying to get AC request going through the ecu. Just use a trinary switch (~$30) to control a fan. I'm doing this on 2 swaps, works great.

96gt4.6

iTrader: (5)

Yes it can be done, have done it many times on many swaps.

Pin the ECU like stated a few posts above.

Then, use your tuning software to change the pin outputs from Recirc operation to Fan operation.

I would provide screenshots in HP Tuners of this, but not at home computer at the moment.

But yes, it without a doudt can be done.

And yes, Silverado's cam with electric fans starting around 2005-6ish. My 2006 Silverado has them.

psiconversion

iTrader: (5)

Second 96GT. We tune all of our truck computers for electric fan control (unless a customer doesnt want it).

Jon
PSI

t72ss402

iTrader: (10)

I think 2005 is when the trucks came out with eletric fans. My 05 truck has them. Caddi's and Yukons may have come out with them sooner, not sure on that though.

Tim.

aknovaman

iTrader: (7)

Easily done as the PCM and operating system are the same as a 2002 camaro. Copy the PCM settings from the camaro file, set the ac type as above and you are good to go.

01WS6/tamu

iTrader: (37)

It's easier to flash the pcm for a camaro vin and fans and everything works perfectly in relation to fan speed vs ect and fan speed vs ac high side pressure right off the bat. 12200411 pcm used in trucks and cars and a ton of different apps.

G-Body

iTrader: (4)

I only run a single speed on mine but its now easy to switch in HPTuners.

Switching the A/C request to a 12v signal on the green/blue PCM`s is much more difficult than switching the fan on the red/blue.

vannatta20

iTrader: (4)

I have a 2000 PCm from a drive by wire unit in a tahoe.. The electric fan control can not be programmed in. It doesnt work. I found out I have to flash to a new OS that supports the fans. I dont know how to do that.

dirtlmiller26

whats a good switched power wire to splice into for the relays that go to the fans?

camarotucker

Can you elaborate on this. Which pin would A/C request (12+) would be?

G-Body

iTrader: (4)

See this thread http://www.hptuners.com/forum/showth...est-type/page2. HPT just added the A/C request feature. I haven`t tried it yet, but you should be able to reset the blue/green PCM to analog cycling and put a +12v signal to Connector C2 pin 17 Pin 43 will provide a ground output for the a/c clutch relay control and pin 55 will expect a - input from the a/c low pressure sensor. (I can`t confirm but by looking at the 2003 chevy express van diagrams it looks like the PCM expects an open circuit on pin 55 when the A/C pressure is within range and a ground when the a/c pressure drops below minimum)

jpcheef98z28

Can I splice the blue wire for the fan with the existing recirculate wire in pin 33 and have both work at the same time? It should work if the recirculate wire in the pcm is a ground like the blue fan wire.

Kawabuggy

iTrader: (1)

I'm going through this right now myself. Have an '02 Silverado with 6.0L swap, running a 411 PCM with 2001 Silverado O/S, with RED/BLUE connectors, and just did the E-fan conversion today. I got my fans from an '06 Silverado and have the factory wiring harness and fuse/relay box. Everything is wired up, but it's not working correctly. I have the GREEN fan control wire pinned to pos. 42 in the BLUE connector, and the BLUE fan control wire pinned to pos 33 in the RED connector.

Problems;
* Passenger side fan (#2?) starts running as soon as the engine starts and never shuts off
* A/C compressor turns on and runs with the fan controller in any position other than "OFF" regardless of if the A/C button is depressed or not

There was a GREEN wire already in pos 33 in the RED connector which I've learned is a A/C Recirc wire. I pulled that wire and just taped it up and put the BLUE fan control wire into that position.

My questions;
#1 Should I put the A/C Recirc wire back into position 33 and just use a relay to give a (-) signal to turn on the 2nd fan when the A/C is active?
#2 If I wire it such that the 2nd fan is on anytime the A/C is on it will basically run even if I'm doing 65 MPH down the freeway.. Is it really necessary to have the fan running even if there is enough airflow over the A/C condenser & radiator? Should I just wire in a pressure switch that will only kick the fan on at a pre-set A/C pressure? I assume that pressure will build due to heat. Adequate airflow over the condenser should keep the heat and resultant pressure below the threshold of the switch. Work?
#3 WHY is my low speed fan staying on all the time?

I'm reading all I can right now about this and there are HUNDREDS of posts scattered across the web with conflicting information. I have HP tuners and have presently copied the fan control data from a '02 Camaro F-body. I will try those settings in the morning to see if the fans work better, same, or worse.

Kawabuggy

iTrader: (1)

JPcheef-I do not believe that you can join the fan control wire, with the A/C Recirc wire like you are mentioning. They are two completely different circuits, meant to do two completely different things. Further, when you *attempt* to turn pin 33 into a fan control circuit, you have to go into the tune and change the circuit type to "fan control #2". Look here; HP Tuners>System>A/C>Hardware>Recirculation Fitted> then choose Fan #2 from the drop down menu. At that point, you are telling the software that you have now added a fan to that pin. You cannot-IMO, tie the 2 wires together.

What I'm learning so far is that even if you change the drop down to show FAN #2 it does not work. Many posts are discussing having to do a complete Over write with a different O/S just to be able to control 2 electric fans independently with the 411 PCM. I'm still looking for a CORRECT answer as well. If I figure something/anything out, I will post back here with the fix.

Pedro C

hello, can you provide me witn a screenshot of the tune settings? i have my ecu hptuned for the fans to turn but they only tunr an a low, the high speed does not work. any ideas?