You may want to pick up a cheap vacuum test kit to see if there is sufficient vacuum at the turbo. Check all pipes for leaks.
The solenoids will only get voltage when the ECU wants a vacuum (or not, don’t know which way it goes).
On startup, my EGR vacuum was “sucked” then eased off after a few seconds (10-20)
On startup/idle, my turbo vacuum was sucked and stayed sucking till the van wanted to change its position.
So, on my van, after say 20 seconds, as EGR vacuum request is “off” and Turbo vacuum request was “on”, I’d expect different voltages at the solenoid as they are doing opposite things. Its all from the ECU. Easier to test with vacuum kit.