2000 Silverado E-Fan Question...

[GAMEOVER]

I installed an 18" Electric fan on a 2000 Silverado 5.3ltr 4WD. I wired up a relay and used pin #42 on PCM blue connector. I know pin #42 supplies the ground to turn on relay....In the tune I made changes so fan will turn on! But as soon as I start the truck the fan click's on and stay's on. I changed the turn on/off temps, switched to series parallel fans and then to back to auxiliary fan...:help2:
In the scan tool under DVT controls I activate the cooling fan setting and the fan turns off. Weird!!! I can turn on and off the fan while under DVT controls... But as soon as I de-activate the fans turn on again...!!!:shock: Anyone know why the fan is staying on? Should I try pin 33 on red connector? This is a first for me.....Will post up tune file.....

Thanks in advance!

[GAMEOVER]

Anyone?

[Aloicious]

Anyone?

is this a mark VIII 2 speed fan by any chance?

it sounds like a wiring issue to me.

if it helps, here is the schematic I used for my Mark VIII fan, its a single 18" 2 speed fan, I have it tuned as low speed is fan #1 programming, and fan #2 is high speed. using series/parallel settings IIRC. I'm not at my tuning computer at the moment. the diodes, LED(s), and maual override switch aren't required, but they are optional. I also didn't draw them in, but the power lines should be fused for safety.

if you're not using a 2 speed fan, you can wire it the same as the low speed side, just pull your 12v switched to pin 85 on the low relay and ignore all the high speed stuff.

http://i461.photobucket.com/albums/qq337/guitargeek1968/2speedfanwiring2relay.gif

[GAMEOVER]

I have it wired just like your low speed diagram, except 85 is wired to Pin #42 for negative trigger from PCM, and 86 is wired to 12 volts.
The fan is a Jegs or summit 18" 1 speed fan... I'm trying to find out why the PCM is triggering the Fan on on start-up and doesn't turn off. It just stays on.... Maybe it's something in the tune that Im overlooking....

[Aloicious]

I have it wired just like your low speed diagram, except 85 is wired to Pin #42 for negative trigger from PCM, and 86 is wired to 12 volts.
The fan is a Jegs or summit 18" 1 speed fan... I'm trying to find out why the PCM is triggering the Fan on on start-up and doesn't turn off. It just stays on.... Maybe it's something in the tune that Im overlooking....

hmm...I can't take a look at it right now, but I'll try later.

[Chevy366]

I think 30 should be (+) to fan and 87 battery (+) . 30 at rest contacts 87a , triggered 87 .

[Aloicious]

I think 30 should be (+) to fan and 87 battery (+) . 30 at rest contacts 87a , triggered 87 .

it doesn't matter if 87a isn't used.

[GAMEOVER]

I'm using a 4 pin relay... I'm 99% sure Battery goes to 30 and fan + goes to 87 and since it's negative trigger(PCM pin #42) 85 goes to pin #42..... 86 any 12+ volt source
Maybe it needs to be a 0411 PCM... IDK!
I'm pretty much stuck right now! Owner is picking truck up later this evening......

[Aloicious]

I'm using a 4 pin relay... I'm 99% sure Battery goes to 30 and fan + goes to 87 and since it's negative trigger(PCM pin #42) 85 goes to pin #42..... 86 any 12+ volt source
Maybe it needs to be a 0411 PCM... IDK!
I'm pretty much stuck right now! Owner is picking truck up later this evening......

you are correct on the relay wiring.

I thought you were using a 411. I would think your PCM would be the same, but perhaps that is the issue. Paul or Ross may have to answer that for you.

I still can't check the tune, I'm at work without wireless internet on my tuning laptop, but make sure like the AC pressure settings aren't too low, making it switch on all the time or something.

[GAMEOVER]

It's the stock PCM from the truck, it's a 2000 Silverado with OS 09381344. I replaced the stock fan & clutch....These are the parameters i tried lowering and raising but PCM doesn't respond

[Mr. P.]

The trigger (ground) wire goes to Pin 42. On your PCM, Pin 33 is internally wired for another purpose; on the trucks, the PCM does not support 2-speed efan operation until 2003 and the redesign of the AC climate control circuit.

Mr. P. :)

[GAMEOVER]

The trigger (ground) wire goes to Pin 42. On your PCM, Pin 33 is internally wired for another purpose; on the trucks, the PCM does not support 2-speed efan operation until 2003 and the redesign of the AC climate control circuit.

Mr. P. :)

OK, but what would be causing the fan to stay on, on start-up? Maybe the PCM is bad? Maybe the 1999-2000 OS don't support e-fan operation!
Every 01-02 0411 PCM that I've used for transplants has always worked...Man I hope I don't have to change the OS or PCM...

[Mr. P.]

OK, but what would be causing the fan to stay on, on start-up? Maybe the PCM is bad? Maybe the 1999-2000 OS don't support e-fan operation!
Every 01-02 0411 PCM that I've used for transplants has always worked...Man I hope I don't have to change the OS or PCM...

Pin 33 in your PCM is used to control the recirculating door (climate control); when Delphi made that PCM that pin is grounded all the time. We have run into the same issue 3 times now installing efans into pre-2002 trucks, I resorted to a custom relay box with the high trigger wire plugged into pin 42 and the low trigger wire activatedby the AC compressor.

If your AC system has the simple AC high-side safety switch then your PCM will only support one fan circuit; if you have the later (2003+) high-side pressure sensor then your PCM will have both the internal circuit and OS support for dual-speed efans.

Mr. P.

[gmh308]

Is your A/C all gassed up to pressure?

[GAMEOVER]

Yes, AC is gassed up... I've tried different pressure settings and fan is still on....

[GAMEOVER]

Pin 33 in your PCM is used to control the recirculating door (climate control); when Delphi made that PCM that pin is grounded all the time. We have run into the same issue 3 times now installing efans into pre-2002 trucks, I resorted to a custom relay box with the high trigger wire plugged into pin 42 and the low trigger wire activatedby the AC compressor.

If your AC system has the simple AC high-side safety switch then your PCM will only support one fan circuit; if you have the later (2003+) high-side pressure sensor then your PCM will have both the internal circuit and OS support for dual-speed efans.

Mr. P.
Mr. P.
I am using PIN#42, I'm not using pin#33
That makes me believe that pin#42 is grounded all the time too....What else would it be?

[67SS509]

When using that OS select the "Auxillary Fan" instead of "Series Parallel Fans" and it will work fine. Just ignore fan settings for fan #2.

[GAMEOVER]

I already tried that, no luck though....

[67SS509]

I already tried that, no luck though....

Missed that in your posts. Don't have access to my laptop right now but I have done that year model. It was pin 42 and I used Aux Fan setting but can't say which OS right now. The OS can make a difference.

I suggest taking a digital volt meter from 12v to pin 42 and see if indeed the PCM is turning the fan on.

[GAMEOVER]

Missed that in your posts. Don't have access to my laptop right now but I have done that year model. It was pin 42 and I used Aux Fan setting but can't say which OS right now. The OS can make a difference.

I suggest taking a digital volt meter from 12v to pin 42 and see if indeed the PCM is turning the fan on.

Yeah, that's what I'm starting to think, OS must make a difference...

[Chevy366]

Okay , my stock 2005 HD 1500 fans run at first start , I used a modified Nelson Harness (they ran a full speed at start up then) , by me , at first , then found the stock harness part # for a 2005 1/2 ton and got the harness from GM (had to buy a forward light harness that had the fan harness attached , striped the fan part out) , it runs at start up both fans , then turns off after 15 seconds , something to think about .
Why , my theory is the PCM is doing a fan check .
Seems weird the scantool can turn it on and off correcly .

[GAMEOVER]

I guess I'm going to try & convince owner to replace his 2000 PCM with a 2001-2002 0411 PCM:nixweiss:

[ScarabEpic22]

I guess I'm going to try & convince owner to replace his 2000 PCM with a 2001-2002 0411 PCM:nixweiss:

Arent they the same physical PCM?? Can you just full flash the 112151226 (or whatever OS you know Im taking about, 02 Fbody OS) in?

[GAMEOVER]

We'll thats what I thought...:)

[GAMEOVER]

Man, this sucks couldn't figure out why fans were staying on... I had to buy and install a E-Fan thermostat...

[cme265]

what O.S. were you trying to use, i had the same problem with a 2000 tahoe O.S. 12205612, ended up using O.S. 12208322 out of a 2001 silverado and the fans worked just fine (had to use the auxillary fan setting to turn both fans on, no big deal for what i was working on)