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2018 Kinetic Blue Ex-Cab ZR2 V6
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Discussion Starter · #1 · (Edited)
Thread summary
Issue:
Steering wheel randomly locked up during long drive. Power assist was degraded at the time.

Factors leading up to cause:
Poor fitting universal steering boots/bellows were used for an experimental heim joint tie rod setup. Boots did not adequately fit or seal the steering rack from the elements. Additionally, tears in the boots were formed and dirt/debris/water was allowed to enter.

Root cause:
Contaminated power assist mechanism dramatically increased friction and created a very gritty rotational action, similar to an extremely dirty ball bearing unit. The dirty mechanism, translated what was a small bind, into a fully locked steering input shaft(steering wheel). Due to the loss of power assist at the time, it was virtually impossible to push through the bind. Loss of assist was likely linked to water intrusion in the main control harness connector at the assist motor. Dirt was found inside the connector, while all other connectors were clean.

The temp fix to get home:
Shaking the wheel back and forth was able to kick the assist back on and push through the bind. Restarting the truck reset the power assist. It was observed that the longer steering input was not received, it increased the chances of it stopping, so a constant feed of small movements was needed to keep the assist working. Was able to drive home like that.

The actual fix:
  • First fix attempt will be to clean all components of old grease and dirt, refill with fresh heavy duty grease and reassemble.
    • Next attempt, if needed, will be to replace steering rack shaft and Electric assist mechanism (sleeve, main unit bearing and loose ball bearings).
    • Last attempt will be to replace the entire rack with new ZR2 unit (PN 84670798).
    • Possible assist motor replacement for ZR2: PN 84494269
  • Clean all electrical connectors thoroughly and use dielectric grease to help protect connections from future water intrusion.
  • Replace steering boots/bellows to achieve good fitment and sealing.

Removing rack:
  • 18mm top bolts (one on each side, top of front engine crossmember)
  • 13/16" lower bolts (one on each side, front face of engine crossmember)
  • 7/16" input shaft bolt (must be taken completely out, steering wheel straight)
  • Disconnect locker and axle disconnect connectors.
  • Easier to remove two large plugs at front of engine crossmember vs plugs on assist motor.

Removing rack shaft:
  • Remove dust cover/seal from input shaft
  • Remove four 10mm bolts holding torque sensor cover.
  • Remove cover.
  • Unplug torque sensor
  • Remove input shaft nut cover
  • Remove input shaft retaining nut
  • Tap input shaft outwards, through top of rack.
  • OPTIONAL: Remove shaft preload tensioner.
  • Push rack shaft towards driver's side
    • Catch any loose ball bearings as the rack shaft exits the assist mechanism
  • Remove all remaining ball bearings from assist mechanism (72 total)
  • Remove rack shaft.

How to remove assist mechanism from housing:
  • Use a drift or punch to unthread and remove locking collar.
  • Grab assist pulley and pull straight out. Unit bearing is NOT a press fit. Tap housing with rubber mallet if needed.
  • NOTE: there is a shim on either side of the unit bearing. (Rack housing, shim, unit bearing, shim, locking collar.) When reinstalling locking collar, collar should sit flush or slightly recessed from housing surface.

Misc notes:
  • 18mm top bolts (one on each side, top of front engine crossmember)
  • 13/16" lower bolts (one on each side, front face of engine crossmember)
  • 7/16" input shaft bolt (must be taken completely out, steering wheel straight)
  • 10mm bolts for all small fasteners on rack.
  • 15/16" Input shaft cover bolt
  • 17mm input shaft nut
  • 46mm tensioner lock nut (1-13/16" can be used, but not ideal)
  • 1" hex - tensioner bolt

------------------------------------Original post----------------------------
Making this its own thread.

Had a rather large scare a little bit ago. Preface this by saying that my steering has been acting up since I went chasing for puddles after a rainstorm a couple weeks ago. Was on my way to the Grand Canyon, along the I-15 when the steering assist faded. Ok, not a massive deal, it usually just does that for a few degrees of wheel movement, then it's back. But this time, I tried to make a slightly larger correction and the steering completely locked up. Felt like the steering wheel lock when it's in park, but it wasn't the column lock, it was from the rack. Was able to slow down and get it to abruptly break free which made the truck swerve. Played with the wheel to see behavior and it was really notchy with a couple instances of locking. Turned the truck off, then back on 馃槀 and it reset. Was able to limp it home. One of the characteristics of the issue is that if you stop providing steering input for a while, it happens. So I proceeded to jiggle the wheel for a whole hour back home. The "spaghetti bowl" near downtown Vegas was extremely sketchy with the thought of my steering locking up, in the back of my head.

Luckily I was on a straightaway when it happened, or it could have been catastrophic. Rack is coming out tomorrow for examination. My hunch is that it's full of water and causing stuff to freak out. Ever since those puddles, it was loud during steering movement, almost like a gritty bearing, so water definitely got into it. I would take it to the dealer, but I have a heim inner tie rod setup with some kinda janky boots, so they would more than likely refuse warranty since I opened and modified the system. They have refused me for less. Time to learn more about the crappy steering on these trucks. Yay!
 

Premium Member
2018 Kinetic Blue Ex-Cab ZR2 V6
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2,497 Posts
Discussion Starter · #3 ·
Well that sucks. I saw your inner tie rods, time for better boots? Electric steering is great for economy but I'm not 100% sold on reliability. Could it be a chipped tooth? Or does it bind in different positions?
I have better boots waiting to install. I'm not convinced it's a chipped tooth or debris, as it was binding dead center. All it took to temporarily resolve was a restart, so i'm almost certain it's an electrical issue. I plan on completely disassembling the rack, so i'll know more after that happens.
 

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2018 Kinetic Blue Ex-Cab ZR2 V6
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Discussion Starter · #7 ·
This little write up may help?
Could also be a rock or something down in the area directly below the oil filter. I dropped a socket down there and backed out of the garage to get more light on it. The steering was completely locked by the socket, which I retrieved with a magnet but almost impossible to see even with an inspection scope. Obviously a really bad "trap" in that area. This might not fit your description, but something to be aware of.
Thanks guys, I'll take a look into those. I'm just gonna chill for the rest of the day. Something about realizing that this issue could have played out dramatically different, really changes the mood. And this is the second major steering related incident I've luckily come out of unscathed.
 

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2018 Kinetic Blue Ex-Cab ZR2 V6
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2,497 Posts
Discussion Starter · #8 ·
This little write up may help?
This is likely part of the problem since it started after basically driving through a flood, but it only points out the loss of power assist. My issue was the wheel completely locking up. Almost like the electric motor seized or was powered on for left and right assist at the same time. I didn't get any warnings or CEL either.
 

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2018 Kinetic Blue Ex-Cab ZR2 V6
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2,497 Posts
Discussion Starter · #10 ·
I wonder if this is in any way related to the 2015 MY recall, even though your truck probably doesn't fall in the VIN range?
That's the same recall as mentioned above. I'm definitely not in the VIN range. I believe it's part of the problem. I mentioned that the assist mechanism is very loud, so that's evidence of dirty water getting into the main tube of the rack. With the electric motor at the bottom of the rack, I'm guessing it's filled with water, along with every other orifice. 馃し馃徎鈥嶁檪锔
 

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2018 Kinetic Blue Ex-Cab ZR2 V6
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Discussion Starter · #12 ·
IIRC, GM had expanded the recall to some later model years or was looking into it? Might be worth some more research.

That electric power steering is one thing I wish they had not put on these trucks, I think a traditional hydraulic power steering would be less vulnerable to these kind of issues.
After getting denied a shock warranty because of scrapes on the frame, I'm extremely doubtful they will accept me for a recall after I modified my steering. I'll definitely be doing more research, but I still need to tear the rack apart and at least clean it out.

I would love to do a traditional hydro steering and never have to worry about this ever again. The only thing they are susceptible to is a slipping or broken belt.
 

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2018 Kinetic Blue Ex-Cab ZR2 V6
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Discussion Starter · #14 ·
That had to be a very scary experience.
Like you said, the puddle play would seem to only explain a power steering lose. The streering whell locking is totally differemt.
Did anything else stop working while it was locked up? Doesn't even sound to have any of teh same characteristics as the ignition problem GM had in the past. Then faulty ignition switches, which could shut off the engine while the vehicle was in motion.
The truck was cruising at 75, with no issue or warnings on the dash. The steering wheel just wouldn't budge. It was the first time in a very long time, where I had virtually no control of what was happening. I'm just EXTREMELY fortunate it happened on a straight away. I like to drive my truck like a sports car in the canyons, both on and off dirt.

This will definitely not be a wasted second chance. I'm hoping to at least gain some knowledge on how to disassemble the rack, look for any vulnerabilities and maybe even find some places to improve strength/performance. I may even look to see if hydro steering is possible. Won't know until I get in there.
 

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2018 Kinetic Blue Ex-Cab ZR2 V6
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Discussion Starter · #21 ·
Is the steering wheel lock mechanical or electronic on the 2nd generation? It would be nuts to make it electronic, but things that don't need to be electronic on vehicles have been such since at least the mid-80s.
I'll check.

When electrical power steering goes out on these trucks, it is much harder than the old hydraulic power steering. The first thought is that it is locked up. It is almost impossible to steer.
Trust me, I know the difference between locked and no assist. I've been into my front suspension and steering well over a dozen times, and I turn the wheel unassisted all the time. This system is easier to turn vs a traditional hydro. I had nearly all my strength into trying to turn the wheel when it was locked. It was locked.
 

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2018 Kinetic Blue Ex-Cab ZR2 V6
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Discussion Starter · #27 ·
It was hot, so I stopped at the first sign of "I think I should get a new rack."

It's been two weeks since it went swimming in the puddles and the boot still had water in it. Some water dripped out as I took the boot off. The spiral for the E-assist had some good rust pits on the outer edges and a fair amount of dirt/debris/grit caked into the greased portion where the assist works it's magic. That's definitely what is making the rack loud when I turn.

I'm gonna be buying a used rack, to swap and compare parts, just incase something is worn or failed.

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2018 Kinetic Blue Ex-Cab ZR2 V6
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Discussion Starter · #30 ·
Well definitely having the debris in the is not good.

I would of thought being that these are 4 wheel drive vehicles and capible of off road activity that that would of been sealed up a lttle better
For a stock truck with factory steering components, they are very well sealed. But I have a retrofitted UTV heim clevis with custom inner tie rods. Long story short, the boots I'm using are not large enough for the heim joint retrofit. Both sides have tears in them. It's very difficult to find a steering boot with a 2.5" large opening that isn't necked down after that flange.

The next step up that I found, is specifically for a full size Raptor heim setup, which I have on the table. I was planning to modify those boots to seal up the rack. Here's the size difference.

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2018 Kinetic Blue Ex-Cab ZR2 V6
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Discussion Starter · #45 ·
Sounds kind of like you knew it could get water in it with those boots and you weren't all that surprised it failed?
Yes, I knew about the potential for water entry, and I was ok with a simple failure. I've had the notchy steering at center before and it went away. But this lockup was completely out of left field.

Wonder if there鈥檚 an alternative. (Imagines Saginaw box in there lol)
I'll be looking to see if there is any room for activities. I'm not sure a Saginaw box would fit since the radiator is somewhat close to the front crossmember. A traditional hydro rack and pinion with pump should definitely be possible. I know the V6 Camaros around 2013 had a hydro setup. After some looking and measuring, I'll be able to make a better assumption. The main problem would be what rack and how far do I wanna go to make it work. Nothing is going to be a direct bolt in, so a bunch of fab work is gonna be required. Shorten the rack, steering shaft, mounts, plumbing.

I will repeat. I have driven vehicles where hydraulic power steering went out. When my Canyon PS went out, there was no comparison in the effort required. You could turn it, but both hands gripping the wheel and pretty much all you could exert. My wife would be dead if it had happened to her.

However, it was not like the steering column was locked, but if you were not rolling, was no chance of turning that wheel.

In my case, a restart fixed the problem temporarily and I got to experience it about a dozen times before I got it in the shop.
Interesting. I turn my wheel with the truck off all the time, on and off the ground. Yes, it takes a good amount of effort when not moving, but I don't struggle. I wasn't able to move the wheel while doing 75. It broke free as I was slowing down to pull over.

A restart did temporarily resolve it as well. When it was happening, it was very notchy and locked a couple more times, but as soon as the restart happened, it went back to normal.
 

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2018 Kinetic Blue Ex-Cab ZR2 V6
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Discussion Starter · #47 ·
Got the rack out, which had some water in it. Pulled the cover from the recall that was mentioned, and everything was clean and dry.

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It was definitely dirty and gritty, but after pulling the motor out, I found something interesting....

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At this point, the only things acting on the rack shaft are that roller sleeve (which is just a ball bearing unit that slides in the spiral grooves on the rack shaft) and the actual steering input shaft. Here's some very interesting video of it binding up. Gonna continue to disassemble but my theory is the small amount of grit in the roller sleeve is what is stopping the movement. The intermittent loss of assist is what is making it dangerous. The sleeve spins 7-8 times per one input shaft rotation, so the reduction is significant enough that a small bind from a piece of grit translates to a locked feeling at the input shaft. Kind of like riding a bike in the high gear from a stop. On a smooth surface, no big deal, but something as minor as a curb will stop you in your tracks.

 

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2018 Kinetic Blue Ex-Cab ZR2 V6
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Discussion Starter · #48 ·
She nasty. The ball bearings (there are 72, for four separate spiral channels) were dry as hell and the layer of dirt on the spiral shaft is gnarly. Also the bearing unit for the sleeve is gritty. Forgot to mention that all the plugs had silt in them, which means water was in them. Some dielectric grease should solve that part. The spiral portion has pitting underneath the dirt, from being dirty, so that is trashed and needs to be replaced as well. Looks like I'll have some spare parts. 馃し馃徎鈥嶁檪锔

I'm 100% positive the root cause of the lockup was the filthy assist mechanism. With the assist working, it can push through the grit, but without it, the reduction ratio is too much to overcome manually. To put it into perspective, the assist motor has a 2.7:1 reduction on the sleeve (41 and 111 tooth pulleys) and the sleeve has a 7.5:1 reduction on the input shaft.

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2018 Kinetic Blue Ex-Cab ZR2 V6
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Discussion Starter · #50 ·
That is ugly.

These things are extremely sensitive. I can see where that amount of crud, the technical term for the residue you see, could easily cause the system to fault out.
Ya, it is bad. Moral of the story is if you open the system, make damn sure it's sealed back up. I knew it was possible to damage the rack with the heim tie rods, but it never crossed my mind that I would damage the E-assist with some dirt.

I really just need a new shaft and the assist sleeve assembly. Debating on buying a cheaper used rack and just salvaging those parts specifically to rebuild my rack. I don't even necessarily need to replace the electronic parts either, just make sure they are cleaned and the connectors sealed up with dielectric grease. Don't really want to spend $900 on a new rack, if I don't have to. Looking at some part numbers online, the rack appears to be compatible cross the board. Some specific part numbers in the motor and tie rods, but the center section seems the same. 馃し馃徎鈥嶁檪锔 Just need to make a decision soon.

Side note, there's really not much room for improvement on these racks. About the only thing I can see is to try and prevent any flex in the housing and save it from breaking. Polyurethane bushings and/or a center mount/brace would be the fix. The assist mechanism has steel gears and a somewhat thin, but wide belt, so that should be fine. I doubt the assist motor can produce even half as much torque to break that. Would be nice to source spare belts though. Overall, reducing the effects of shaft flex transferring into the housing, and making sure the connectors are greased up to keep water out, would be my main recommendations. Then people can feel better about running tie rod sleeves. It'll just end up bending the tie rod in a different location. 馃槀
 

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2018 Kinetic Blue Ex-Cab ZR2 V6
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Discussion Starter · #54 ·
Steering locking up at 75 mph, ahhh
Hope I never have a problem, bad enough going down a steep hill to a T intersection and blowing a break line, shoved in 1st and work the clutch to slow down fast.

That looks rough, glad you got it figured out.
Does anything look chipped, broken or excessive wear?
Had a chance to tear down an thoroughly cleaned for closer inspection, so see about after cleaned, re lube and put back together, atleast out of curiosity if there is play or worn, ir still locks ?
Everything looks ok, as far as I can tell. The bearing surfaces are pretty rough though, but it could be thrown back together without replacing anything. It would require a really deep cleaning. The grease had a ton of dirt in it, so the locking problem would probably be resolved with fresh lube.

I would like to replace the parts, but a clean and lube isn't a terrible idea to get me back on the road. Really wishing I had a bench grinder with wire wheel attachment right about now. 馃槀
 

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2018 Kinetic Blue Ex-Cab ZR2 V6
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Discussion Starter · #59 ·
This scenario is extremely specific to a broken, and neglected boot. I probably have 1000 miles of offroad dirt in there and a couple good rainstorms to help it flow into the sensitive bearing areas.

I'm definitely not keeping trail spares with me. I know what happened and how to prevent it from happening again. Once I get the raptor boots to fit, I won't have to worry about dirt intrusion, so no more locked up episodes, which is my main concern.

A boot inspection as well as a full vehicle once over, is always good practice before and after big adventures. The more common issue is the intermittent loss of assist. That is more electronics related, therefore the connector cleaning and greasing would be appropriate. I'm hoping that can solve that issue for me as well, but I won't hold my breathe. The input torque sensor harness does plug directly into the assist motor, so it makes sense how the swim could have affected that connection.

After some thinking, I'm just gonna clean everything and put it back together. I almost feel obligated to try to fix it instead of abandoning a potentially usable rack. A new unit costs $900+, and if this cleaning can save myself and others some coin, that's worth it. As of right now, I haven't used any special tools.
 

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2018 Kinetic Blue Ex-Cab ZR2 V6
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Discussion Starter · #61 ·
Got everything cleaned up but I overlooked the shaft preload tensioner. It's a 1-13/16" or 46mm lock ring, with a 1" hex. I tried to reassemble the rack, but I need to loosen that tensioner or the shaft is never going back in. Gave her one careful try with the pipe wrench, and stopped before I destroyed the lock nut. Ordered the 1-13/16" socket, then I'll use a 1" nut for the hex.

Fun!

Maybe I'll chop up that socket into smaller pieces and make a tool for anyone else wanting to dive in. Could also get a wrench, but it's twice as much as the socket. And with lock nut is all of 3/16" thick.

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2018 Kinetic Blue Ex-Cab ZR2 V6
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Discussion Starter · #64 ·
Well gents, I just pulled the harness off the assist motor and found the main, multiwire control harness has dust all over the inside of it. All the other connectors were clean. So, I might just be right and sealing this is the fix for the assist loss....hopefully.

@Mtn_man that recall is specific to replacing the torque sensor cover, for water intrusion at the torque sensor. That is seemingly resolved in the later model years. So, pushing that recall for my incident doesn't make sense.

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2018 Kinetic Blue Ex-Cab ZR2 V6
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Discussion Starter · #66 ·
So it looks like the off-roading caused the issue.
Remember, the actual locked up issue was two things happening at the same time. Dirty steering rack AND loss of assist. Not one or the other, both at the same time.

To call it off road related is not a fair assumption. The poor quality and fitting steering boots that I used for experimenting with heim steering, allowed a chain of events to occur and lead to the rack feeling locked, ONLY when my assist failed. Had I found the right boots that worked, this would not have happened no matter the amount of offroading.

The assist loss could happen to anyone in wet conditions, since it's a plug on the rack. Hell, the water I went through was on public city roads. 馃し馃徎鈥嶁檪锔
 
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