Help diagnose a power steering issue on my 99' GMC

[txgp17]

Thanks for all the input. I own the OEM service manuals for 99 Chev/GMC/Cadillac C/K series GMTs. The section on ABS is in book #1. I browsed it today but didn't see anything that jumped out at me, but I'm a total novice to ABS.

That being said, I broke out my mechanic's stethoscope and put it on the ABS unit while my wife pressed the brakes to induce the pulsing noise. It was absolutely not coming from the ABS unit on the driver's side of the engine compartment. I repeated the same while I was touching the stethoscope to the PS pump housing, and BINGO, that is absolutely the source of the pulsing/noise.

Now, I gotta read up on the EVO bypass that GM offered so I can implement that when this repair takes place.

I'd also check the ball joints, tie rod ends, and anything else.

Those were all replaced in the last 15,000 miles, and it was sorely needed. I couldn't believe how much better is drove after that.

 

[GoToGuy]

You want answers. I'll do my best to give the right answer based on the provided information. Not some WAG . For those they don't know, download the factory service manuals for your year vehicle here in the forum.
It will be your new best friend. It's written at a grade school reading level so anybody should be able to understand it. I did recommend the 98 service manual book 2 section 5, covers power steering pump and evo. The answers you get are based on the information you provide.
I will not write 18 paragraphs of system explanation or a detailed step by step on complex repairs. . If your here you can read the manual for the complex repair or diagnostic just as well as anyone else.
Carpe Diem.

 

[df2x4]

Here's a link to the GM service manual thread, it's stickied at the top of the "Engine Performance + Maintenance" section. They're searchable PDFs, free to download. '99 is in there, you just have to keep scrolling past the original post. Other members have added to the collection over time.

https://www.gmt400.com/threads/88-98-service-manuals.43575/

Now, I gotta read up on the EVO bypass that GM offered so I can implement that when this repair takes place.

FYI, you can delete the EVO by replacing the pump and pressure line with parts from a '96. This will give you one less fitting to potentially leak vs the delete kit that GM offers (part number 19168825). I used the GM delete kit on both of my '97s, but if my pumps ever go out I'll probably just replace them and the lines with '96 units to eliminate that extra potential point of failure.