Marktainium

ARGHHHHHH....

I need help. I can't seem to get my ecm to turn on my fans. From what I have researched, on my LS2 the dark green wire (#58) on my E38 ECM should send a ground signal when switched. When I switch the fans on through HP tuners it does nothing. If I run the motor till it is well into fan on temp, it does nothing....


(2007 corvette LS2, E38 ECM, in a 1972 Camaro)

dsrour

The E38 uses pulse width modulation (PWM) to control the fan. This is a very efficient way to have a variable speed fan.The green wire goes to the Fan Module and the module powers the fan.
To wire it this way you'll need the fan module(ACDelco #15-80803)
and the wiring harness, which I dont think can be purchased separately. It comes with the fan assembly. The module has an unusal connector.
You maybe able to find a used or broken fan and cannibalize for the harness.

You could also, I think, change parameters of fan turnon with HPT and use green wire to a relay like in older pcms.
The variable speed, though, is cool IMHO.

Marktainium

Now there's some info I can use!!!

Marktainium

A big thanks to rsz288 ! Gave me the parameters to get my fans going. Without these forums this build would be impossible! Thanks to all!

hellbents10

iTrader: (10)

He gave you the proper state diagram? You do not need the module to run the fans just the proper cal in the ECM.

Marktainium

Yes, that's what he explained to me. No module. Works for me now.

samckitt

iTrader: (5)

This is great information. Now I wonder can I wire up my GMPP LS2 controller kit to run the PWM module. Obviously it will need a reprogram to send the correct signal.

eboch

Hi All;

I'm adding to this thread because I think I have a similar stumbling block.

I have a 63 corvette with an LS3 & E38 ECU. The setup is out of a 2008 Corvette (C6). I'm running a Dewitts radiator with SPAL. I have the SPAL connected to a relay which the ECU controls. I have tried a lot of combinations of E38 fan control settings ... but I cant get the fan to work properly. I can get it to come on .... but it stays on. On this is that the LS3 thermostat is a 192degF unit and the Dewitts radiator cap overheats around 215 degF. I'd like the fan to come on somewhere around 200 degF.

I have the fan setting to "discrete" ..... I'm not running a variable speed with PWM controller (I have an on-off relay ... thats it).

Since I only have one fan, I've set the "Desired% vs state" so that the 0>1 cell is 60%, and the 0>1 cell is 40%.. It doesnt seem to make much difference if I use other numbers .... 70% & 50% for example. seems to kick the fan on when the engine is a bit hotter ..... but it still never turns off. I've even tried values like 10% & 5% ... same result.

In the "Output Control vs State" table ... I have 1's in row 1 starting at state 1 (for fan #1). The rest of this table is all 0's.

On HPtuners .... the E38 fan control doesnt seem to have a simple on-temp, off-temp configuration option .... its all variable speed.
Anyone have any suggetsions?

In the "desired % vs ECT" table ... there is only 1 row in that table .... I have 0's up to 97 degC ....and 1's for the temperature above that.

Thanks for any help!!

Cheers
Erik

manny79

HI eboch, did you get this sorted? as I am having the same issue..

eboch

Hi Manny79;

sorted out ... sort of. I'm running a 182deg thermostat and this seems to keep the engine around 198 - 200deg. If you set the fan to come on before that, it'll be on full time. The problem I have is that my rad starts to overflow around 215deg ... so the window for the ECm to control the fan is pretty small. When my fan comes on ... it can only reduce the temp back down to about 200deg ... where the thermostat is holding. So the fan doesn't get turned off by the ECM once its turned on. I think if I ran a cooler thermostat the problem may be solvable. I ordered one to try this ... but the PoS was a dud, didnt open at all. So I have to try and get another one to try out.

Cheers
eboch

Michael Yount

iTrader: (1)

Interesting. I run a new crate LS3 on an 08 Corvette E38 ecu. My new motor came with 187F t’stat. Tested it begins opening at 185F and is fully open by 188F. This results in the driver's side head sensor (where coolant is leaving the block) showing operating temps of 195-197F. I set my aftermarket PWM controller to operate the fans to maintain a 203F operating temp. Under cruise the fans stay off and temps are 195-197F. Slow down, fans come in and fan speed is varied to maintain 203F.

manny79

thanks for the reply, im really after the settings needed to put into HP tuners for me to activate the fan relay. I dont have the PWM system, just a aftermarket thermo, but cannot for the life of me get the setting in the PCM to activate the fans. They either come on all the time or not at all.

eboch

Hi Michael;

I observed similar temps being different (thermostat, head temp). I have two temp sensors ... one at the head-rear for my guage, and the factory one (head-front-drivers side) for the ECU. Under normal driving conditions, the fan doesnt come on. When the car is stationary and its hot out, the temp rises and the ECU turns the fan on.

Does the ECU turn your fans then off once the temp is brought back down to ~ 200deg? .... mine doesnt seem to turn off once the ECU activates it, even though I can see the fans have brought the temp back down to the 200deg area.

Regards
eboch

.

eboch

Manny79

here is my tune. as I've noted, my fan control isnt really 100% working properly. I'm running an LS3 with tremec 5spd. the engine (and tune) were orginally out of an 08 Corvette with auto trans.

My park-neutral and clutch switch arent connected to the ECU.

manny79

Excellent Eboch

Ill have a look and compare what I have in my settings. Thanks a lot mate.

Michael Yount

iTrader: (1)

epoch - I don't use the ecu controlling relays to control the fans. I don't like the big surge of on/off voltage/current that creates with big fans. I use an aftermarket variable speed pulse width modulated controller. It varies the speed of the fans to hold the temperature constant --- as opposed to constant rising/falling temps between set points with the relays. When it's colder out it takes longer for the fans to come on and they don't have to spin as fast to keep the car at the 203F set point. When hotter, the fans come on sooner and spin faster --- but when under fan control, the operating temp sits right at 203F. When I'm moving fast enough that I don't need the fans -- operating temps are controlled by the t'stat -- and my front head temp is 195F-197F. When it's really cool out, I think the little bypass around the t'stat moves enough coolant that I'll see temps a bit lower than 195F. All this with a 187F t'stat. Of course, the set point of the fans (temp off) has to be ABOVE the operating temp you'd see if the t'stat were controlling. Otherwise, once the fans come on, they won't turn off -- because they're trying to control down to a temp that the t'stat won't let it reach.

eboch

Thanks for this info Michael.

I'll recheck my fan on/off settings and see if I can adjust them to better fit with what I'm seeing on the engine temps.

Thanks!
eboch

G Atsma

Michael, I am trying to remember which PWM controller you are using, but maybe the DCC FK45?
How do you like it so far?

Michael Yount

iTrader: (1)

I have two from DCC - the one on the LS3 is one of the originals purchased back in '03 or so. Used first on a 5.0L that was in the car at that time with the dual 11" SPAL shrouded fans. Worked so well I transferred it to the new radiator/engine combo in '15. Worked so well for so long I bought an FK45 to drive a SPAL single 12" for the Corolla a little over a year ago. Equally pleased.

G Atsma

I'm betting the first one is an FK35, which the FK45 replaced. I think I'll go that direction too in the near future.
Did either one take very long to get? I understand summertime has longer delivery times...
I talked with Brian Baskin once with a few questions. Nice guy with thorough answers!