Steering issues... how does the steering system work?

[1-8-4-3-6-5-7-2]

My truck is a 97 C1500 4.3

I know the alignment is way out by how it skips on pavement at slows speeds when turning and it pulls to the right at highway speed. I want to replace all front end parts before getting an alignment. I don't think the alignment is part of the next problem:

My problem is that on the highway, if I start to move the steering wheel either way it will move a bit and then go to nearly no resistance and move way too far, jerking the truck somewhat quickly towards either the other lane or the ditch. Imagine as I start to turn the wheel as working hard to climb a hill and then breaking over at the top and taking off effortlessly down the other side... that's how my steering feels. Kind of like it gets in a bind just off center then overcomes it all at once as I turn.

While typing this I thought "I wonder if something is binding on the shaft between the steering wheel and steering box", but I don't recall noticing this at lower speeds. I'll have to take it for a test drive today and pay more attention. With CV19 going around I'm on my 3rd week out of work and haven't been driving anywhere much.

Please provide any info on anything that I may need to check. Also, could someone explain a bit about how the system works? What are all of the parts and components? I see there looks like an electrical connector on the pump and I've read about something on the steering column.

 

[Pinger]

How does it feel on the way back, ie, centering? Just as jumpy or smoother?

Going a bit leftfield here... the anti-roll bar (sway bar) can influence the steering 'off centre'. Are the drop links and bushes permitting free (in intended directions) motion?

I know I've just arrived on this forum - but why is a steering question in the 'engine' section?

 

[1-8-4-3-6-5-7-2]

How does it feel on the way back, ie, centering? Just as jumpy or smoother?

Going a bit leftfield here... the anti-roll bar (sway bar) can influence the steering 'off centre'. Are the drop links and bushes permitting free (in intended directions) motion?

I know I've just arrived on this forum - but why is a steering question in the 'engine' section?

From memory it returns smoothly. Good point and good thing to check, which is partially why I'm asking so I know what to check for on my test drive later.

Why is it posted here? I'm mostly a wandering idiot and do sill things, and I didn't see any other place either. Off road has a suspension section but not street trucks. If it's in the wrong section hopefully a mod will move it.

 

[2001ZR2]

It's a 97 which has the Electronic Variable steering which is a MFer. Replaced the pump on my 97 Burb and it would bind up like no power steering now it is almost always on the edge of power assist so driving is a bit unsettling if you aren't prepared.

This summer a new steering box and pit man arm and I will add upper control arms to the job so I can have it aligned once.

 

[df2x4]

Your issue on the highway sounds like a textbook EVO column sensor failure. Unplug it temporarily. If it gets worse, might not be your issue. If nothing changes, it is. Unplugging the sensor will put the system in full boost at all times. The sensor in question is GM part number 26064468.

https://www.amazon.com/gp/product/B00GV8PRNK

I've seen them fail in two different ways, one is they go into full boost all the time and the other is they go full boost intermittently. That's why I said if things get worse after unplugging it, it might not be your issue. It still could be.

 

[1-8-4-3-6-5-7-2]

Your issue on the highway sounds like a textbook EVO column sensor failure. Unplug it temporarily. If it gets worse, might not be your issue. If nothing changes, it is. Unplugging the sensor will put the system in full boost at all times. The sensor in question is GM part number 26064468.

https://www.amazon.com/gp/product/B00GV8PRNK

I've seen them fail in two different ways, one is they go into full boost all the time and the other is they go full boost intermittently. That's why I said if things get worse after unplugging it, it might not be your issue. It still could be.

Thanks for that link! I did some searching now that I know what the system is called and I found a post from you from back in 2016 stating this part as what is needed to disable the EVO system, is this the best and most affordable method? https://www.amazon.com/Genuine-1916...=1475693283&ref=plSrch&ref_=mp_s_a_1_1&sr=8-1

Also in that thread someone descibed the problem as feeling like an invisible hand was jerking on the steering wheel, which accurately describes what I feel. I found the connect on the column to unplug the sensor, I'll try that and report back with the results.

 

[1-8-4-3-6-5-7-2]

It's a 97 which has the Electronic Variable steering which is a MFer. Replaced the pump on my 97 Burb and it would bind up like no power steering now it is almost always on the edge of power assist so driving is a bit unsettling if you aren't prepared.

This summer a new steering box and pit man arm and I will add upper control arms to the job so I can have it aligned once.

I find the problem annoying but not unbearable. I am afraid to let my wife drive the truck though because I'm afraid she'll panic and jerk the wheel the other way and then back and forth and out of control...

It would be nice to fix it though for pulling a trailer, I certainly don't need the truck darting around the highway then. I'm leaning towards the "disable" option if the EVO system is my problem, which from what I've read it is.

 

[alpinecrick]

Not familiar with the EVO, but didn't that start sometime in 97? Can the PS pump and steering gear be replaced with say, a 96 pump and gear to eliminate the EVO? Or is there more to it?

 

[1-8-4-3-6-5-7-2]

Well I'm confused now. I unplugged the connector on the steering column and took it for a test drive (50 mph) and the invisible hand jerking on the wheel was gone. It seemed like it steered really easy, so I'm guessing full boost. I plugged the connector back together and it still seemed the same and the invisible hand is still gone. Idk if fiddling with the wires finally broke it for good or what.

 

[sewlow]

The EVO is that thing on the back of the pump which the line connects to.

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Need to remove the C-clip so as to remove the 1st part. It'll slide off once the C-clip is off.
Then you need to turn that thin nut next to 2nd part of the EVO. You can see the threads on the other side which screw into the P/S pump. This will remove it from the pump's housing.

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GM figured out that the system had flaws so they offer an EVO Delete Kit. I looked at that and saw another junction that could be prone to leakage.
I could of just bought the pre '96 line, but I'm cheap. I did mine with low mile pre-'96 wrecker parts.
Just need the one line & this part. $5.00!

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This is the pre '96 line with the extra bend that it needs to get around to the rear of the pump. Also shows where & why you need that 2nd part. Be careful when you pull the EVO off of the pump as there's a puck inside there that will fall out. There's a spring behind it. Just make sure to take note of which way the puck faces before it does drop. It has a crimped edge along one side. I don''t know if it makes a diff, but I don't want to have to take all this apart again if it does matter.

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