It needs to be attached to a full time vacuum source such as a port on the intake manifold.
A small one with vacuum secondaries.
That transmission is electronic controlled. No need for a modulator valve.
The vacuum modulator on a 1989 Chevy K-1500 4wd 5.7 is underneath the transmission. It can be reached from under the car.
It does not have one.
That year model did not have a modulator valve on the transmission.
That year transmission did not use 1
If your speaking of the vacuum modulator for the transmission, they no longer use them on the transmissions with overdrive and electronics. The powerglide, turbo 350 and turbo 400 used to use them.
If your transmission has a modulator it is on the side of the trans and it has a nipple on it for the vaccum line. I you. Mark
If your car has one, take the vacuum line to the modulator off and if there is fluid inside, the modulator is bad.
On the back of the trans. There should be a vacuum line running to it.
On the 440T4 Automatic Overdrive transaxle the modulator is on the front of the case, A vacuum line leads to it from the intake manifold.
The 2001 Chevy Impala vacuum module can be found on the back of the engine. The vacuum module valve will be near the top of the engine.