How does the transmission modulator valve come out of the housing for it?

No shift solenoid D in your transmission .
DTC P0982 Shift Solenoid (SS) 4 Control Circuit Low Voltage
The 3-4, 4-5 shift solenoid (SS) valve (S4) controls transmission fluid pressure acting on the U1 shift valve to position the valve for the appropriate gear. The 3-4, 4-5 SS valve (S4) is a normally open exhaust valve located on the front control valve body. The solenoid is case grounded. The output driver module (ODM), within the transmission control module (TCM), commands the solenoid ON or OFF by providing voltage. When the 3-4, 4-5 SS valve (S4) is commanded ON, the TCM senses high voltage. When the 3-4, 4-5 SS valve (S4) is commanded OFF, the TCM senses low voltage.
If the TCM detects a continuous short to ground in the 3-4, 4-5 SS valve (S4) circuit, then DTC P0982 sets. DTC P0982 is a type A DTC.

Inside transmission .

Overdrive is actually inside the torque converter. Look at the transmission control module. Have it tested for proper operation first. There is a solenoid inside the transmission on the valve body that the module operated. Since you didn't get a fail on the solenoid, the OD clutches may be worn enough to slip. No need to replace the entire transmission, just the torque converter.

with a scan tools look for data of transmission.
then look for A,B,C,D switch data and compare with chart
these valve are there to confirm oil pressure has been going to the right component.
see witch one of a b c d switch malfunction and have a test to wire from transmission to pcm
signal to pcm it's only a logic pattern on and off state
on is grounded
off is not grounded then if wire is ground then it send a message of malfunctionning switch or oil pressure inside transmission but do the outside diagnosis before
hope it helps

If its a THM400 the valve should be in the side just above the pan. It would have a vac hose going to it.
If its not a 400 it probably does not use a modulator valve but rather a solenoid inside the transmission.

Hello shanebuerman: My name is Roger and I will help you. If you are using transmission oil and see no leaks on the ground I would look at the transmission as the source of the problem. If you have a turbo-hydromatic 400 transmission look at the modulator valve. It will be on the passenger side of the transmission and have a vacuum line attached to it. This will be a metal line that runs over the top of the bell housing. The other end will be connected to the intake manifold at the rear of the carburator. When the diaphram ruptures the fluid is sucked out of the transmission and burnt in the engine. Pull the vacuum line from the valve and if there is any oil at the vacuum port you will have found the source of fluid loss. If you have a 700R4 overdrive transmission? and no external leaks.Look at the radiator as the source of the problem. The transmission coolers were known to leak in the radiators. This model transmission does not have a modulator valve. Should you need further help please just ask. Please rate the answer. THank You for using Fix Ya. Roger

Hello, the 2003 impala's dont have a transmission modulator valve. this transmission is electronic controlled by the power train control module. the transmission uses a pressure control sol. inside the transmission instead of a vac. operated modulator valve. if you are having a late harsh shifting problem, this would be more in the area of a pressure control sol. at fault

check for a bad vacum to the modulator valve on your transmission,or a bad vacum to the modulator valve on the transmission. the modulator valve to the trans. works off of vacum from the engine,look for loose or disconnected vacum lines around the carb. or the air induction system. look for cracked vacum lines that seem to be sucking air when engine running at idle speed. in park. the modulator valve [usually] located on the drivers side,of the transmission,is the main cause of shifting failure. if the valve itself is bad, it will need replacement. thank you for choosing fixya.com!

The cause for that could be a low transmission fluid level, a faulty vacuum modulator or no vacuum to the vacuum modulator, A faulty front pump assembly or torque converter, a loose valve body or a blown out valve body gasket, the forward or direct clutch pack has lost line pressure to the clutch pack (could be a plugged up transmission filter) or the frictions are burned up in that clutch pack, or the governor has malfunctioned, usually due to missing or stuck governor weights, or a stuck valve inside of the governor, a small plugged up line filter inside the governor fluid channel under the valve body, and most commonly because of a plastic drive gear at the end of the governor that can crack apart or will have sheared off teeth on the drive gear.

Check the transmission fluid level and inspect the vacuum line to the vacuum modulator for any damage and there should be full intake manifold vacuum to the vacuum modulator. Remove the vacuum line at the vacuum modulator and if transmission fluid drips from out of the vacuum line then the vacuum modulator is faulty and should be replaced to eliminate it as the problem, however there might still be a problem with the governor, the valve body, the forward clutch pack, or the torque converter and front pump assembly.

The valve body can be tightened down and the transmission fluid filter can be replaced, and the valve body and the spacer plate gaskets can be carefully replaced, and also inspect for a small inline screen filter inside of the governor fluid feed chanel if the valve body is removed. (there will be check-balls only experienced mechanics should attempt it).

The torque converter, the front pump assembly, and the forward clutch pack can only be repaired by removing the transmission and except for the torque converter dis-assembling the transmission.

The governor can be removed without too much difficulty and the plastic drive gear should be inspected for any damage to the teeth on the governor drive gear and also the worm gear on the output shaft inside of the governor housing that drives the governor gear. Also check the governor or for any missing or stuck weights on the governor or for a stuck valve inside of the governor.

To remove the governor from the transmission remove the clip over the governor cover and then pry the governor cover off, then the governor will pull straight out of the governor housing. (The transmission cross-member might have to be removed on some vehicles to lower the transmission enough to remove the governor)

Here are some images to help assist you inspect the governor, and let me know if you require any further assistance.

This is possible, to check the valve by going under your jeep and looking at the back part of the transmission. You will see a valve with a vacuum line going to it, it is usually located at rear of trans just above trans pan. To check pull vacuum line off, if fluid comes out the valve is bad and needs to be replaced. They can be purchased at most auto parts stores readily. If no fluid the trans may just need serviced.