It is right behind the right headlight under the battery box attached to the inner fender.
Modulates pressure that controls shift points.
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.
as far as I understand , it does not have a modulator. e4od are electronic. no vacuum shift modulator
On some of the older vehicles the vacuum modulator controlled the shift points of the transmission by using the vacuum supplied from the engine.
Could be no vacuum to the modulator.
I assume your refering to the vacuum modulator which controls transmission shift points. Remove the vacuum hose from the modulator. Using a small screwdriver, turn the screw inside the modulator. It may take several tries to get it right.
Never heard of a "front wheel modulator" on a S-10 Blazer. If you mean hub, it is the wheel bearing assembly. If you meant 4x4 shift solenoid then depends if it is shift on the fly or not. The ABS has a modulator, but not sure what you mean.
Assuming you mean the modulator on an automatic transmission... The modulator help to control the timing of the changing of gears in the tansmission. The modulator uses manifold vacuum to finetune the shift point, lower vacuum means higher load, throttle is open wider, shift point will be delayed.
It's for a modulator valve. The later cars all shift by electronics and signals from the ECM. Yours however still uses a modulator valve and vacuum to assist in determining shift points.
That transmission does not have a modulator valve that makes it shift it is all computor controlled. Therefore it don't have a vacuum line on it anywhere. it does have a small rubber line on it that is a VENT hose.
the modulator valve does not have a screw, however, the modulator located outside the modulator valve may or may not have one.
I had this problem on a car once. If it won't shift by itself, but it does shift when you go through the gears manually, it's the vacuum modulator. Replace it and you'll be good to go.