83 k10 700r4 no lock up

[the427chevy]

hii all i'm new to this forum, but not to (in my opinion) the sharpest looking trucks on the road. the square body chevy, i have an 83 k10 all original, just bought it, and i have no torque converter lock up, the vacuum switch is there, i have 12 volts to the switch, nothing coming out key on engine running, i've checked the brake pedal switches they all appear to be functioning, i have 12 volts to the B pin (left most on the retainer clip side) and nothing to the other two. i've owned several of these trucks and the lock up just always worked i never had to mess with anything, anyone who could shed some light on what i need to diagnose from here would be appreciated

 

[the427chevy]

I will continue to share what i learn as i go with diagnosing this, i have verified the vacuum switch works correctly, engine running it passes power, at about half throttle engine working the switch cuts out, I have found a two wire connector, light blue with 12volts, and a yellow, continuity test tells me the yellow wire is going to D pin on the trans plug, anyone know what this was hooked to? temperature controlled switch maybe?

 

[chengny]

I will continue to share what i learn as i go with diagnosing this, i have verified the vacuum switch works correctly, engine running it passes power, at about half throttle engine working the switch cuts out, I have found a two wire connector, light blue with 12volts, and a yellow, continuity test tells me the yellow wire is going to D pin on the trans plug, anyone know what this was hooked to? temperature controlled switch maybe?

Sorry for the delay - I forgot about this post. Anyway, it appears that the EGR solenoid is missing (or that the LT BLU & YELLOW wires are just not connected to it). See the attached wiring diagram.