Background: '97 SR5 4WD 5vzfe, 5spd, 385,000 miles, and owned since 2018 purchased with 348,000mi. Few months ago the power steering began to groan but worked fine. Added fluid, cool, groaning stopped. Noticed a fluid leak had developed in the pump area, cleaned all around real good, drained all the old fluid out, replaced with new dex/merc atf and tightened everything up, cool. Leak largely gone, no groaning, all good. Month goes by, fluid stays constant, no groaning, but now the PS is nonexistent at idle, or very low speeds, fine while moving over 10mph, or if you throttle up to 2k+. Today I removed the reservoir cleaned out the screen (huge thanks to MTBTim for this) new fluid, air hoses cleaned and tightened up. Problem not resolved, no groaning, no belt squeal. The truck does not idle up when stopped and steering angle applied. Saw some threads about the PS pressure sensor/switch. There is the single wire going to a gray connector behind the pump, I can trace one end of it to what appears a ground on the pump housing itself, the other end I lose down near back of the pump near the pulley itself. Is it possible this sensor has crapped out? If so, possible to diagnose without removing entire pump, or can the sensor be removed and replaced? UBJ's, LBJ's, sway bar links, and some other suspension bits in the area have been replaced during my ownership. There are no abnormal suspension noises or steering rack noises during use. Any thoughts or suggestions. I do appreciate the upper body workout in parking lots, wifey can't drive it like this and she's a real good DD to have.
Thank you all in advance.

Had similar issue on my wife's sequoia. Idle and low rpms was hard to turn, if I increase the RPMs it was easier. I replaced the pump and that fixed it. However, the first time it acted up, I put Lucss power steering conditioner in it and that worked for a few months before reverting back to stiff steering

Good luck

MikeM

Might give that a try. I have a suspicion the sensor that idles up the engine has crapped out. But for the life of me I can't figure out where the frig this sensor is.

Clean the screen in the power steering reservoir . By now your power steering pump maybe damaged from being starved for fluid. You can look in the folders on the top of the folder 3rd Gen T4R DIY Maintenance, Repair and Modification Videos for links to the DIY videos on how to do this project. :-)

Screen has been cleaned. Didn't resolve the issue. I'm attempting to confirm or deny that there is an electric sensor to idle the engine up. One is shown on Rockauto for the '97. Heard that the older ones only have vacuum. Anyone out there with extra brain power able to confirm this? And if there is one, can a pic get posted of exactly where the damn thing is?

'96-'98 is vacuum, '99-'02 is electric. Right on the bottom of the pump. Either two vacuum lines (early) or a small electrical connector (late).

In either case, it is something like 25rpm boost to the engine - mainly it keeps the extra load from the pump from dragging RPM down under heavy loads, not really boosting it up.

-Charlie

OK, definitely vacuum. Those hoses are clear on both ends. I suppose at this point it's a replacement pump then.