1997 Suburban Steering Issues

[tommywass]

I have a 1997 K1500 Suburban. It's my wife's daily driver so I don't drive it everyday, but probably every two or three days. I got in it about a week ago and the steering was not re-centering very well after a turn or even while driving on a curve. I can let go of the steering wheel on a curve and it just keeps following the road instead of wanting to straighten out the wheels. It's strange because it's not a problem that gradually appeared. One day it was totally fine and a day or two later, we have a problem!
I decided to start with a peek underneath while having my wife rock the steering wheel back and forth. Everything looked tight. Next, I had an alignment done and the caster was fine (they fine tuned some stuff but nothing was way out of whack). I was secretly hoping the caster was way off because in my mind, the symptoms point to that. That is as far as I've gotten. I feel like I'd be throwing likely unneeded parts at it with my lack of diagnosis ideas on this one.
What else can I say about the symptoms?
-There's not much play (if any) in the steering wheel that I can tell.
-Vehicle's steering won't recenter well after turns.
-When driving straight, the vehicle has no self-correcting tendencies. There's no binding, tightness or noises/clunking in the steering.
-If you were to turn the truck within 5 or 10 degrees of center and took your hands off the wheel, it would keep going in the direction you pointed it instead of straightening out.
Thank you for any ideas you guys may have!

 

[OR VietVet]

The first thing I thought about is a caster problem. That seems to have been ruled out. I would also assume the alignment tech inspected the whole front end for a sign of what is causing the problem and I was then going to say a binding ball joint and that could still be something to do with it since inspection on a rack or the feel sitting still may not show the problem but it may when under a load driving. The next best guess is that you are having an internal problem in the steering gear and while you are inspecting for that, check the frame mount of the gear for any cracking.

 

[tommywass]

Thank you for the suggestions. I have recently (maybe 6 months ago) replaced the upper ball joints because a previous alignment revealed some play. I was wondering about the lower ball joints. I'll check those for play and/or binding. Do you have any idea how I could check the steering gear?
I did go back to Firestone (where I had the alignment done) to talk about the problem. I suggested tweaking the caster a bit even though it was within spec. They told me you shouldn't tweak an alignment that is withing spec to accomplish desired driving "feel." They essentially told me it's a old vehicle so it's going to have some play. I don't want to give up that easy! I'll let you know what I find with the ball joints.

 

[OR VietVet]

The print out on the alignment should show a bit of a caster lead, higher caster number, on the right side to allow for road crown. If is even or has a left lead, have a qualified alignment tech adjust accordingly. Hell, post the last alignment readings here so I can see what the tech was saying cannot be adjusted. I hate lazy techs like that. The specs could very well be where I would desire them but he should have pointed that out to you with the readout.

Checking out the steering gear is best left to a professional and I have, at a time or two over the years, disconnected the center link from the pitman arm and then can turn with engine off and on and see how smooth it is. Look at the gear mount at the frame for any frame cracks. They can be small but really show under a load.

 

[exp500]

Try flushing the steering = about 2 quarts of ATF. Jack up front, turn ignition switch out of lock and move tires full left full right while its draining a few times, to feel for binding ball joints or something else. Then flush with fresh fluid, while still jacked, cycle steering full left right a few times. Try to stay off the stops while cycling steering as the relief valve will pop. if you are moving junk around in the system don't want it under relief valve ball.The steering gear adjustment on top of box may have been tightened too tight. look for wrench marks on the lock nut.Too tight and pump is on pressure all the time. Remember that shops these days don't have experience, just shit utube told them.These trucks are nearly impossible to get too much caster,usually its a chore to get enough to drive straight and hold. I believe 3-1/2 degrees is factory max recommended, 2 is ok, 1-1/2 will wander unless toe is 1/8 inch or more.Toe should be.040-.080, otherwise too much scrub,tire wear and poor gas mileage.. 1/2 degree max left right difference for crown. (0-0) for camber. With ride height at factory settings. Get out a tape measure too. I don't trust any alignment shops I've found last few years.

 

[tommywass]

Thanks for the responses guys. Here's my alignment report. Based on the chat, it sounds like 2.9 should be fine. That number is consistent with another alignment I had done about a year ago when I bought new tires. Because there's no change between the two, I doubt that's the source of my problem.

Maybe I'll try flushing the system. Also I can't see any play in the lower ball joints. I'm still scratching my head because one day it was good and the next, it was messed up. So I doubt it's some part gradually wearing out (like a ball joint). It's something that was fine one day, and broken (or clogged) the next. I considered the EVO sensor, but it doesn't seem like the symptoms match up.

Also (long shot), my wife mentioned that the cruise control stopped working at about the same time time the steering started acting weird. I can't imagine they're related, but I figured I'd mention it anyway.

 

[OR VietVet]

I always insist on a caster lead on the right front. I see it is set at even. No play in ball joints but what about binding?

 

[tommywass]

I'm not sure about binding. I was going to take the steering knuckle off yesterday to feel for any irregularities but I stopped because once I saw how much I'd have to take apart to get to it, I figured I'd just replace them. So I have to get a set before I jump in so I can get the job done all at once.

 

[OR VietVet]

You can separate the tie rods from the knuckle and turn them by hand to see if you feel a binding. Careful not to damage the grease boot when you separate. Don't use a pickle fork. Remove the nut except for the last 2-3 threads and get a BFH and hit the knuckle where the tie rod stabs in the hole and it will drop loose and then remove nut to allow it to drop all the way out.

 

[exp500]

Try jacking the front and moving the tires L & R by hand, should move by hand without disconnecting steering gear. Maybe you will find something likely wrong.

 

[tommywass]

I'll check out the binding by taking off the tie rod ends. The wheels turn freely when I jack up the front and turn them by hand.
After some more research I'm really starting to think it's an issue with the EVO steering system. If any of you really know that system and how to diagnose issues with it please let me know! My theory is that I have full steering pressure all the time, which is why the wheel is so easy to turn and the caster is not always enough to center the steering after a turn. I've heard it referred to as "easy steer" in my research. It sounds like most people opt to remove the system and still end up with overly "easy" steering. I'd really prefer to try to fix my system and deal with the EVO issues as they come (probably having to use sensors out of the junkyard because they're not produced anymore).
So far I've replaced the solenoid valve on the back of the PSP with a junk yard part with no change. I don't know how to test the valve though.

 

[Joseph Garcia]

Years ago, I had a steering issue suddenly pop up on my 1997 Yukon SLE. When driving at speed, if I nudged the steering wheel to the left, nothing would happen, and my Yukon would continue going straight. When I nudged the steering wheel a bit more to the left, the Yukon would suddenly lurch to the left, really to the left, and veer into the next lane. Definitely not safe.

I blindly ended up changing the steering box, the power steering pump, the pitman arm, and the idler arm in succession, and my issue did not resolve.

I finally found an EVO system bypass assembly, sold by GM (clearly, GM knew that this particular rendition of this feature was a failure), and I installed it, and my steering issue was resolved. As I recall, it was a simple steel tube with the correct fittings on each end to bypass an electric solenoid connected to the power steering pump and one of the power steering fluid lines. It cost me about $80 from GM, but I could have fabricated it myself for about $10.

I don't know if this has relevance to your issue, but I thought that I'd throw it out there.

 

[tommywass]

Thanks Joseph! That is very relevant to my issue. That's the fix I know most people would suggest. I'm a bit worried because I've read mixed reviews on the bypass. Some say the steering feels loose or "easy." What was your take on how it felt after you bypassed it? I know that everyone has their own opinion on how steering should feel but I'm curious what you thought.

 

[exp500]

I was going to suggest EVO- but the way you described the issue it doesnt fit. My EVO fix was to Replace Power steering pump and pressure line. I used a 96 as components, left the EVO valve plugged in behind the pump,then tywrapped to the bundle out of the way. That prevents EVO codes. I also re-shimmed the pump relief valve to drop the pressure 200 lbs as I'm really picky as how my stuff drives. (I want road feel). I've done this for 3 trucks so far, no codes,complaints, call backs. I do suggest buying a new pump pulley- it seems to me to be about 50/50 chance of destroying it on removal, and I like the one with holes in it so ya don't have to remove pulley to remove pump. I also like Lares rebuilt. (never a problem-Yet). Then you can focus on alignment. There is a 4x4 shop nearby that has been recommended for alignment that I haven't tried.( the 5 that I have tried all suggested repairs that were unnecessary and did alignments by changing toe and ride height, worst one was 2" different L/R.) Been doing my own for last 3/4 years- it works well but takes alot of time to get perfect.

 

[Joseph Garcia]

Thanks Joseph! That is very relevant to my issue. That's the fix I know most people would suggest. I'm a bit worried because I've read mixed reviews on the bypass. Some say the steering feels loose or "easy." What was your take on how it felt after you bypassed it? I know that everyone has their own opinion on how steering should feel but I'm curious what you thought.

The steering was a tad bit less responsive for very small movements in the steering wheel, which was the original intent by GM to improve, with the EVO feature. But, for any larger turns of the steering wheel, I did not notice any difference at all.

For me, it did not make the truck any less driveable, and it made it a whole Hell of a lot safer to drive.

 

[tommywass]

Thanks guys.
I've done some research on both of those options. exp500, what's the reason you used a pump and pressure line off a '96? I thought the '96 components didn't have EVO, but you mentioned still plugging into the EVO valve behind the pump. (maybe you meant a '96 steeeing gear??) Would you mind clarifying a little? Because I'm suspecting my EVO valve isn't working anymore, could I just shim my existing valve in the '97 pump? I do like the idea of being able to adjust the assist by using shims until I get the feel that I like.

 

[exp500]

The EVO valve is a solenoid valve- on is full pump flow/pressure.(thats why steering gets jerky)EVO Valve is on back of p/s pump pressure port. EVO sensor on steering column under hood. The GM bypass kit is a p/s pump fitting on a tube that threads into pump in place of EVO Valve. ($60.00) The 96 power steering hose does the same thing. Any reman pump you get usually comes with a bypass BTW. Just cannot buy them seperately except thru GM. Shim kit Bill's Hotrod P/N 1001.Shim kit adjusts pump relief valve. Maybe Jegs Has it too. Don't go too low on pressure or parking is a squealing pump and hard steering. Sometimes 850# is enough. Tires/wheels change the numbers. Remember everything goes thru computer? Computer controls EVO valve? Leave valve Connected doing nothing.( remove pump, remove valve from pump). If you want to keep your pump you need a relief valve assy.(junkyard) any GM style 80's-90's threads in.

 

[tommywass]

Update: I got a shim kit and a '96 high pressure line. Before I install them, I had a thought which I haven't mentioned on this thread (I thought they were unrelated until now). My cruise control went out about the same time that I noticed the steering over-pressurization. What if they're both getting a bad speed signal from the VCM/ECM (I think they're all one computer). The speed sensor on the transfer case seems to be fine because the speedometer works and the tranny shifts. But what if the speed output, when it comes out of the computer to the EVO steering and the cruise is not good? Then I think I may get all the symptoms I'm experiencing. When I test the speed input prong on the plug that goes into the cruise control module, I'm not getting the results I think I should be getting (according to a YouTube video). All that being said, does anyone know how to test the speed output of the the ECM to make sure the steering (and cruise) is getting the signal it needs? I'd like to confirm that before I start trying to shim the pressure valve in the pump.

 

[wjburken]

Update: I got a shim kit and a '96 high pressure line. Before I install them, I had a thought which I haven't mentioned on this thread (I thought they were unrelated until now). My cruise control went out about the same time that I noticed the steering over-pressurization. What if they're both getting a bad speed signal from the VCM/ECM (I think they're all one computer). The speed sensor on the transfer case seems to be fine because the speedometer works and the tranny shifts. But what if the speed output, when it comes out of the computer to the EVO steering and the cruise is not good? Then I think I may get all the symptoms I'm experiencing. When I test the speed input prong on the plug that goes into the cruise control module, I'm not getting the results I think I should be getting (according to a YouTube video). All that being said, does anyone know how to test the speed output of the the ECM to make sure the steering (and cruise) is getting the signal it needs? I'd like to confirm that before I start trying to shim the pressure valve in the pump.

There are a few reasons that your cruise could have gone out and the timing maybe a mere coincidence. Check to make sure all your brake lights work. GM has a habit of disabling cruise if the vehicle senses a burnt out taillight/brake light as a way to let you know. Also check you brake light switch. Not sure about your generation of vehicle, but on the GMT900’s that switch has been the cause of many a cruise controls to not work.

I’m not saying you don’t have a problem with the modules as you mention, but I’d check some of the more simpler, more common causes of cruise not working before you go down the path of testing/replacing a module.

 

[exp500]

EVO not part of cruise system. Cruise boxes fail alot! As long as you are not having trouble with the combination switch- turn, 4ways, horn ect. then probably cruise box. 40-50$ junkyard. Cruise testing box is dealer only. Swap in your buddies known good box for a day. Trere are a few threads on cruise box they are all interchangeable I think.