E fan issue

[livingez_123]

I put the OEM fans on my 01 Denali. I used the OEM harness. The ac control works perfect, but I cant get the low speed fans to turn on. I have 2 custom tunes and neither one works. The harness has been tested both on the truck and on the bench, and all works fine. I tested the pin at the ECM and can trigger the low speed fan like it should. I replaced the ECM pin just in case, but that didn't work either. I have gone through the wiring from ECM to the relays. I checked the lead from pin #42 with a test light, and it won't trigger at any temp. I'm out of ideas.
The tunes are coming from the guys at Diablo.
Any thoughts?

 

[YukonXL04]

Are you sure the truck is getting up to temperature to signal the fans to come on?

 

[livingez_123]

Are you sure the truck is getting up to temperature to signal the fans to come on?

Most definitely, I had my tuner plugged in, and I sat in the driveway and watched the temp go up. I finally kicked the ac fan on when it hit 240°, and it sure cooled down fast. So I think it's getting up to temp. Driving around the temp never went higher than 198°

 

[Rivieraracing]

Just got your message, can you post up the wiring diagram that you have for the '03-'06's, I'd like to take a look at it!

 

[JennaBear]

I believe the problem is that you have an 01. Need to change OS.

 

[livingez_123]

I believe the problem is that you have an 01. Need to change OS.

Explain please Jenna.

All of the people I have talked too say it's just a programing change. LS1 Fans, Nelson say the same thing, it should work with the fans turned on in the programing.

 

[livingez_123]

Just got your message, can you post up the wiring diagram that you have for the '03-'06's, I'd like to take a look at it!

Here you go.

Other than the AC being changed to a 12v trigger, it's should work.

 

[Time2Kill]

*EDIT*

Nevermind, just realized it was a Diablo tune.

 

[Rivieraracing]

Here you go.

Other than the AC being changed to a 12v trigger, it's should work.

Got your email and printed it out to look at it tonight and show some of my electrical smarter coworkers!

 

[livingez_123]

I think it just might be the ECM/PCM. There is nothing else it can be.

 

[scoobyxj]

I think it just might be the ECM/PCM. There is nothing else it can be.

I was thinking I read somewhere that the 00-02 ECM's did not have the ability to control E fans. That if you did E fans on a 00-02 you needed to use a standalone system that basically monitored the coolant temp via a sensor..

 

[livingez_123]

I was thinking I read somewhere that the 00-02 ECM's did not have the ability to control E fans. That if you did E fans on a 00-02 you needed to use a standalone system that basically monitored the coolant temp via a sensor..

If that's the case, there are a bunch of company's out there that make the harness for the 00-02 trucks and it plugs into the ECM. You just need to get the ECM programed properly.

 

[Rivieraracing]

I was thinking I read somewhere that the 00-02 ECM's did not have the ability to control E fans. That if you did E fans on a 00-02 you needed to use a standalone system that basically monitored the coolant temp via a sensor..

They sure can control e fans as long as you get someone with EFI live (Blackbear can do it) to turn on the appropriate pins to do so! Been running electric fans for about 3 years now in our '02 denali and they work great!

---------- Post added at 06:40 PM ---------- Previous post was at 06:38 PM ----------

Hey Robert, you don't happen to have a schematic of the ECU pin layout for our '00-'02's, do you? Want to compare a few things to the schematic you sent me and can't seem to find what I'm after online!

 

[YukonXL04]

So I was under the impression that only the 03+ used the dual ecm pins, and the 00-02 used a single ecm pin and then a AC trigger. So there is another way for the 00-02 crowd?

 

[livingez_123]

So I was under the impression that only the 03+ used the dual ecm pins, and the 00-02 used a single ecm pin and then a AC trigger. So there is another way for the 00-02 crowd?

You are correct, one pin up to 02 and the ac is tapped into under the fuse/relay center under the hood.

You could always go with a stand alone system like the Flex-a-lite controller

 

[ccapehartusarmyINF.(ret)]

okay what is the point of E fans because i live in probably the hottest state in the country and my tahoe never overheats in the dead of july 115 dagrees plus with my stereo im pretty close to the limits of my 250 amp alternator current wise

 

[Rivieraracing]

okay what is the point of E fans because i live in probably the hottest state in the country and my tahoe never overheats in the dead of july 115 dagrees plus with my stereo im pretty close to the limits of my 250 amp alternator current wise

Heck, just the ice cold AC all the time from having e-fans would be well worth the money for you, also nice to not have the extra drag on the serp belt as well!

 

[ccapehartusarmyINF.(ret)]

dude my AC is to freakin cold my perents when they owned said this to if i turn my ac on full in the summer in 30 minutes you could hang meat in my car there would be ice cicles hanging from my nose when the fan is just blowing on the cold setting its like almost running as cold as the AC asside from running a power hungry car stereo a 250 amp alternator helps with alot of other minor issues

just curious i see on yer tahoe youve done a black bear tune do they tell you to run high octane gas with there tunes, unless a tune increases your compression ratio over 10:1(wich im pretty sure it doesnt) then yer wasting yer money like that was topic gone over in depth when i went to school cars like corvettes with an LS1 or LS6 have a high compression ratio like 13:1 unleaded has a higher flash point then super

 

[Time2Kill]

dude my AC is to freakin cold my perents when they owned said this to if i turn my ac on full in the summer in 30 minutes you could hang meat in my car there would be ice cicles hanging from my nose when the fan is just blowing on the cold setting its like almost running as cold as the AC asside from running a power hungry car stereo a 250 amp alternator helps with alot of other minor issues

just curious i see on yer tahoe youve done a black bear tune do they tell you to run high octane gas with there tunes, unless a tune increases your compression ratio over 10:1(wich im pretty sure it doesnt) then yer wasting yer money like that was topic gone over in depth when i went to school cars like corvettes with an LS1 or LS6 have a high compression ratio like 13:1 unleaded has a higher flash point then super

You run 93 octane with tunes because they increase the timing which REQUIRES high octane. You can't change compression with a tune.

LS1/LS6 is no wheres near 13:1, its 10.5:1

 

[livingez_123]

Well the dealer showed me today that my ECM is current, and no updates are available. So, I'm not sure what to do next. the fans are wired correctly, the ac fan works, but no signal from the ECM to trigger the low speed fans. I guess maybe find a core ECM and start over, or just sell my Diablo Trinity and go with EFI live and have BlackBear tune it.