So I've been struggling for a LONG time with this one:

Situation:
94 Blazer, SBC removed, BBC installed
16197427 PCM
4L60 Trans from Finish Line Trans- top of the line build
Tune from a guy here in Denver

Symptoms:
After a couple years I noticed that TCC would hunt in and out around 30 MPH 4th gear. Would finally engage solid at higher speed and light load


Troubleshooting:
Long story- here is the short of it
Modified bin (using Tuner Pro) to completely remove TCC activation- still would hunt in and out... as verified by touching the brake (then it would stop).
Put o-scope on TCC tan/black wire
The ECM is pulsing the TCC clutch - even in park huh???
100ms period or so, 20ms engaged, 80ms disengaged
tap the brake, pulsing stops
get up to cruising speed and the line goes low as expected to engage the TCC
Whenever the TCC is supposed to be dis-engaged... the signal pulses

After a LOT of time I determined (binary search) that the Enable Throttle Kicker flag is the culprit.

Disable Throttle kicker, TCC line does not pulse and works as it should
Enable Throttle kicker, TCC line pulses


This seems VERY jacked up. But I confirmed it 6-ways to Sunday.

Maybe you guys all know about this... but in case not... I wanted to share... maybe it will help someone someday.


If anyone is interested, I can post a link to a video of all of this.