Ok fellas, I've done extensive searching on the site but can't find an answer. I am working with a 2001 WT Silverado w/o AC and installed a 34" radiator and E-fans from a 2010 Silverado with the upgraded cooling package (oil cooler). I put it all together with a black bear harness hooking the green wire in the harness to the green wire in the loom by the alternator and the blue 42 pin in the PCM as per instructions. So here's my problem...

My truck doesn't have AC and every thread I found about these issues people talk about the green or green/black wire. I hooked it up to the green, and no HIGH fan operation. There is no green/black wire in the loom, but a green/white wire and tried that too, but no fan HIGH operation. Fans work correctly on LOW operation via the PCM as checked with HPTuners and when we tried to turn the fans on manually with tuners nothing happened. So what am I missing? I've seen in some of the other install threads that there's a blue wire that runs to the PCM that controls fan high operation? I'm thinking that's the problem because as of now I have fans that only work on low.

Sorry for the lengthy post but I didn't want to leave anything out, wow my fingers hurt. Thanks for looking.

 

Tried pin #33 and nothing, anyone have any ideas? Help a brother out!

 

I was having the typical problems after installing my BB harness. After trying everything I could find on here, as well as as having a few buddies check it out.
I took it to a local shop where another buddy works and after spending several hours checking everything he could think of, he decided to put the basic fan segment in my tune and it works like a charm!

The BB harness is installed per instructions.

 

Do you have air conditioning on your truck? So you have the green wire from the black bear harness running to the green wire on the harness by the alternator?

 

Yes I have AC, and the harness is connected per the instructions that came with it.

 

AFAIK the 99-02 pcms just have single speed control through the pcm. The high operation comes on the same time as the compressor clutch, as is actually connected to that wire.

 

This can be fixed.




You have to change your stock settings to this to make the PCM have two fan outputs. Now then for a truck with AC such as mine and 05+ series parallel fans in order to get decent fan operation with the AC on here is what you have to do. If you find some stock fan settings say for a 05+ truck and plug in the settings on a 99-02 your fans won't come on with the AC until the AC system pressure reaches 325 psi. The reason is there is no variable AC high pressure switch on the 99-02s. Instead what it works off of is the AC high pressure recirculation switch which was there to provide an input to the PCM to tell it to ground pin 33 to turn the AC on recirculate once the system pressure got to high. What you have to do to get around this is set the G0903 #1 fan turn on by AC temp to something like like 50 degrees F. By doing this anytime the PCM receives an AC request with the coolant temp above 50 degrees F the PCM will automatically turn the low speed fans on. The downside to this is you only get low speed fan operation with the AC on regardless of system pressure. However I have never found the need for the high speed fans. It got to 116 degrees this summer and I could sit there idling at Sonic blowing 38 degree air.

 

I think you guys are missing the point of this thread. His truck doesn't have A/C, so there are no pressure switches, no compressor, no HVAC control head, etc.

How can we get a second(for high speed) signal from the PCM for the BlackBear harness? I'm still digging on this one for you Jake.

 

Why not a manual switch?

 

Would like to have the fans 100% controlled by the PCM. A manual over-ride switch could be added if he wants to, but I don't know if he wants one.

There has to be a way to do this, I just haven't figured it out. For now, it's just running one fan speed.