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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 😂 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!
 

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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?
 

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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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2021 Black \/6 4WD Z71 Crew Cab Short Box
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This little write up may help?
 
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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.
 

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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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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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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. 🤷🏻‍♂️
 

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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. 🤷🏻‍♂️
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.
 

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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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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.
 
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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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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.
From everything you mentioned. I would lean to something in the steering column or its connection to the front end.

I have had the electric power steer "go out" due to overheating. It just was like not having ant power steering at all. Not being locked up.

Thankful you were going straight ahead at the time.

I hope you find a cause for it. And then a solution so it does not happen again
 
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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.
This is pretty scary. I bet you are right. When power steering fails you should still be able to steer manually! Jeez.
 
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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.
 

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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.
 
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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.
Good question. Sometimes when I hop out of my truck the wheel turns pretty easy. Like the power is still there. I'm not really sure if it even locks, maybe just powers down. I'll let you know after I drive it next. :)
 
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