Nelson Harness - Convert 1 Wire To 2 Wire?
 

OK, I bought the harness for my rig, 2000 Tahoe (1 wire to pcm, 1 wire to AC). I'm also using a factory GM 05+ fan assembly.

I got everything installed last weekend and it worked flawlessly. Forgot to mention, I also have EFILive and tuned the pcm to turn on the fans. Again, worked perfectly, turned the fans on at 195, low speed, perfect. Then this morning it was a bit cold outside and needed to use the defrost, which of course kicks on the AC pump. No biggie, worked fine until about half way to work. Now the damn thing only works on low speed even when the AC pump kicks on. Also, I can watch my voltage gauge drop every time it trys to engage the AC so I turned the defrost off and continued on to work. Also smelled very hot at that time. I briefly checked it this morning after I got to work, the low speed fans still operate, didn't feel any hot or melted wires etc..

I realize it's still preliminary and I haven't actually checked the problem completely, but what all is involved with converting the harness to a 2 wire, pcm controlled setup? I read somewhere that it can be done, just didn't find any details about it. Something about changing the positive to negative output of pin 33 (or vice versa) using another relay?

At this point I don't care about not having the recirculation control, I just want a reliable fan setup that operates like it should. :sigh:

Any help is appreciated.

Mike

if it makes you feel any better, i just installed a harness from ls1fans and im not too impressed with it either.

maybe you should be speaking with Alan....Im sure he can troubleshoot your issue and or take care of you

i got a harness from painless. it is not controlled by the PCM but it works flawless. couldnt be happier.

You will still have recirculation with the 2 wire harness. You will just not have auto recirculation where the PCM commands it without selecting it on the dash. They should really just stop selling one wire harnesses.

Good to know.

So has anyone converted their 1 wire harness to be a a 2 wire setup? I'd like to be able to control the high speed fans through the pcm and not some rinky dink, backwoods hill billy way using the ac trigger.

I wished I had done more research on this before pulling the trigger.:sigh:

Mike

i feel your pain. hopefully someone answers.

i might go with a factory harness if i come across another. kicking myself for not pulling it out of the truck i got the fans from. only 05+ ive seen at the self serve yards in last 2 year.

Check out the painless harness. It comes with a temp sensor that goes into your head. Not a BS probe. Its heavy gauged wire and has good relays. Painless has a great rep.

Thanks for the input. I'd rather modify this harness to use the editable on/off temps in the pcm though. That way I can adjust it later if I change out the t-stat etc...

Someone has to have done this conversion. Anyone? I really don't feel like paying another 125.00 for another harness. :( A wiring schematic on the 2 wire setup would probably work too.

Mike

I know you can find the 2 wire harness on this forum if you search.