1996 JDM car and I have gone through everything. Tested everything I can think of. The turbo actuator will open under manual pressure from the hose at the Turbo Control Solenoid. It will also open with manual vacuum.
However, it will not operate with the car running. Now.... get this... if I bypass the Turbo Control Solenoid and just run a piece of tubing between the in and out, the actuator works as soon as the car is started. I tested the Turbo Control Solenoid and it tested good but I still replaced it. Same issue. I'm at a loss... it almost like the ECU (stock) is not telling the Turbo Control Solenoid to open.

Any thoughts on what else to try?

 

Long time since twins! When you say turbo control solenoid in the singular.....just in case you're unaware, there's two, one on the ACV and one in the black box for the vacuum and pressure signals to the actuator.

 

Yes. I have been under the assumption the the one inside the black box is working due to the fact that if I bypass the other one, the actuator moves. Maybe this is a bad assumption?

 

Normally when a snafu occurred in those twin days, I'd power/vacuum/pressure test all pertinent solenoids, actuators, check valves, vacuum and pressure chambers, etc, just because working on the system was not frequent enough to be on top of every permutation......and to minimize murphy.

You should be able to hear it click with power if it's working, even without dissassembling the box. Quite a few over here have found the integrity of the box itself a major part of their problem