What is a Happy Knob?
What is an ICCU?
What is IAT and does it really change the timing?
These answers are as follows:
I happy knob is a potentiometer from usually 0-10k ohms. It goes on the IAT (inlet air temperature) wiring.
Will this knob do any good on a stock PCM for the 3800SC 97-03? Not really. Lets look at the timing tables for this PCM.
This is a table lookup for IAT stock. Notice that IAT at 104 degrees and .32 g/cylinder the timing changes to -1 degree. It pulls -1 degree from the called for timing at that moment.
Now this is a modified table for the "Happy Knob"
This table is set for Plus 8 degrees at the most. Your happy knob will dial temperature setting and that will be the degrees added per grams/cylinder of air flow.
The ICCU is sold by ZZ Performance. It will change timing based on this IAT and injector pulse based on MAF.
Notes of interest. 3.3k ohms will give you 69-72 degrees on the IAT reading via a OBDII scanner.