Electric Cooling Fans Running S..L..O...W

[Badger69]

Wrapping up my LS build and my damn cooling fans won't spool up.

I have them wired from the ECM and am using a dual LS1 set up from a 2000 Camaro. First fan runs when I hit 205, second is supposed to kick on at 215 per my program.

When I run the truck, the temp climbs to 205 and the first fan kicks on, but it spins super slow. Then at 215, the second fan starts up, but also spins VERY slow.

I used HP Tuners to force the fans on and I can hear my relays clicking. Getting 12 volts to the fans. Fans work when disconnected and wired directly to the battery. Verified temp gauge is correct by running HP Scanner. I assume it is a grounding issue, but my ground meters out.

Any ideas of what to check next?

Thanks all!

[mongocanfly]

Are the fans getting the full 12 volts when run by the ecm?

[Daaaanz67]

Don't think the ECM supply the 12 volts only provide ground circuit to turn on relay, 12volts comes from relay via another 12 volt circuit that comes from battery supply through relay, relay carries the amp load.

[mongocanfly]

I just remembered I had the same issue on mine...dang getting old...on mine my ecm was only running one fan slowly and wouldn't run fan 2 when I talked to my tuner he said they just had the same problem on another truck and figured out the problem was the truck ecm was only setup from the factory to run one fan not two.something about them adding the second fan into the program was messing up the signals. I sent him my ecm and he fixed it and sent it back to me..worked perfect..

[homemade87]

I think you have it wire wrong . If only one fan is running than it is wrong . Both fans run at the same time on low speed ( run in series ) and high speed ( run in parallel ) . You have to have a 3-relay system for the fans to run like GM intended .

In low speed both fans will run half speed . In high speed both fans will run full speed . So if you only have one of the fans powering up one at a time it is wired wrong .

And also early pcm have to have fan 2 turned on . I think 04 and newer they were moving to all electric fans . Some 04 may have to have it turned on if it had a reg fan .

[mongocanfly]

..

[mongocanfly]

Homeade that's not how mine works...mine works just like badgers only at different temps..when they fixed my fan problem they set it up for where fan 1 comes on full speed at 150..fan 2 don't run..when it hits 170 fan 2 comes on at full speed and then both fans are running full speed. And yeah, I've caught grief on here for my fan temps being set so low already but it works. I used the psi harness and it only has 2 relays. One for each fan so it controls each one separately..my problem was with the truck ecm from factory it only had one fan to control and having 2 temp setpoints was causing my problem..but they figured out how to fix it

[dayj1]

Originally Posted by Badger69

Any ideas of what to check next?

Thanks all!

HP tuners has several options for the "fan type" that you are using. If you have it set to "PWM electric" or "variable speed" it would behave just as you're describing. It would be worth a double check to make sure you've got it set right. Based on how you've described your setup, I believe you'd want is set for 2 "discrete" fans.

[Badger69]

Great suggestions.

I have my fans programmed in Hp tuners as discrete and am set up to run two fans. PCM should be supplying ground in my set up. My harness came from Tempe Speed and has been great so far. Maybe there was a wire swap some where in the triple relay setup.

I thought it was strange that only one was running so this kind of confirms my suspicions.

I need to pull my seat to get to everything. All the electronics are under there.

[aknovaman]

What ecu and file are you running?

[Badger69]

Originally Posted by aknovaman

What ecu and file are you running?

Running a 2009 e38.

[Matt Cramer]

Check to be sure that both your power feed and ground wires can handle the full current of the fans. A bad ground can also do this.

[aknovaman]

If the relays are clicking, the fan settings are incorrect

[Badger69]

Originally Posted by aknovaman

If the relays are clicking, the fan settings are incorrect

Can you share your fan settings so I can compare? I am set to descrete, 2 fans, but maybe the other settings are wrong.

[Badger69]

Originally Posted by Matt Cramer

Check to be sure that both your power feed and ground wires can handle the full current of the fans. A bad ground can also do this.

I used good wire and metered my ground. All seem fine

[aknovaman]

OP pm me your email and i can send you a file to compare yours against.

[Hart_Rod]

Originally Posted by aknovaman

OP pm me your email and i can send you a file to compare yours against.

[aknovaman]

Waiting on PM. ................. ?

[Badger69]

Originally Posted by aknovaman

Waiting on PM. ................. ?

PM sent....thx.

[Andy4639]

This is how mine is setup. I don't think any ECU is suppose to run the fans straight off the ECU ground wire it's only a trigger wire for the relays.

http://www.hawksmotorsports.com/dual...ans-3-100-cfm/

PRODUCT DESCRIPTION
Dual Fan kit, 82-02 Dual Fan Kit 12" Fans 3,100 CFM, This is a universal dual fan kit for pretty much all 82-02 f-bodies. it comes with (2) 12" fans with 225 watt heavy duty fan motors that produce 3,100 CFM, it also comes with a wiring harness, 185 degree temperature switch, and a nylon tie kit to attach it to your radiator. Shipping is not included, call or email for a shipping estimate.

Deminsions:
26" wide x 15" tall
Flows 3,100 CFM
3.94" Depth
26.6 Amp Draw

[aknovaman]

It's not a wiring issue, its the PCM file settings that are wrong. The ls2 and ls3 ecu settings are different than the ls1 PCM. When not running an inline PWM controller, the ecu settings need changed to make the ecu output go to a constant ground (not variable speed) like they run on a factory vette,etc setup when fans are commanded on.

[Badger69]

Originally Posted by aknovaman

It's not a wiring issue, its the PCM file settings that are wrong. The ls2 and ls3 ecu settings are different than the ls1 PCM. When not running an inline PWM controller, the ecu settings need changed to make the ecu output go to a constant ground (not variable speed) like they run on a factory vette,etc setup when fans are commanded on.

Thanks for the tune file. I checked it against what I already had and they were very close. I made a few tweaks based on what you had aned loaded it up.

Fans came on as expected and both spool very slow again.

This has to be some kind of wiring issue so I will have to pull my seat out and get to all my wiring and walk through each piece step by step.

At this point I'm thinking about buying a fan controller and just skipping the computer all together. I just really wanted to make it all work as it should. I just had back surgery so I'm pretty limited on what I can do right now. I have a good friend who is very mechanical who can throw a controller and for me and at least I'll be able to drive it.

Thanks again for all the help everyone. If there are any other suggestions please let me know.

Very best,

David

[mongocanfly]

Did you ever get someone to look at your ecm setup for the fans? That's what caused my fan issues

[aknovaman]

If you have hp tuners, can you command them on using scanner and do they run at full speed?

[Badger69]

Originally Posted by aknovaman

If you have hp tuners, can you command them on using scanner and do they run at full speed?

I tried that as well and no, they do not run full speed.