Chevy Colorado & GMC Canyon banner
  • Hey Everyone! Enter your ride HERE to be a part of this months Ride of the Month Challenge!
101 - 120 of 143 Posts

·
Registered
Joined
·
1,863 Posts
Discussion Starter · #101 ·
As an engineer who works on electronic power steering (EPS) design / integration into a vehicle, this thread peaks my interest for obvious reasons. No, the company I work for doesn't supply the 2nd Gen Colorado / Canyon steering gears so I do not know specifics and I won't share things I shouldn't.

@hoooogan

Great thread and good job investigating this on your own.

I didn't get a chance to read all 100 posts yet in detail, here's some of my thoughts.

On Locked Steering Cause:
1. A chipped rack or pinion tooth causing binding is rare, but can happen due to a high impact event (curb impact, off-roading, etc)
2. Water & Debris intrusion due to leaking boots (bellows) that cause corrosion / contaminant build up on the ball nut and/or rack teeth. This typically happens due to either a cut boot or improper fitting of the clamps. We run destructive testing for this exact scenario, and the pictures you posted look just like our post destructive testing gear tear down. Over time the corrosion / contaminants build up results in lesser assist (higher human input at the steering wheel) and the driver should start to feel or hear a crunching phenomena and possible stickiness during rack movement. The crunching / stickiness / binding are worst after letting the truck sit for a while (overnight), then after you steer left / right the corrosion can "wear-in" to the point where steering starts to feel normal again. Eventually, the corrosion / contaminants either cause a sudden locked steering events requiring very large steering wheel torque by the driver (120+ lb-ft) to break throught the bind or freeze up the whole steering gear. From my experience, the water doesn't intrude into the motor due to a shaft seal, but I'm sure it's happened to someone at some point especially if the motor is below the rack due to packaging reasons.

Torque and Pinion Angle / Position Sensor Connector:
1. There shouldn't be dirt inside the connector. Did you disconnect / reconnect this at some point? Adding a little grease to the connector seal can help prevent future water / contaminant intrusion. Obviously, clean that up as best as possible.
2. If you lose electrical connection between the torque sensors and motor, you will lose assist.
3. If you disconnect the torque sensor connector while the vehicle / steering gear is powered on, you WILL set trouble codes. Typically, reconnecting and cycling ignition will put the trouble codes into history.
4. Torque sensors use a change in the magnetic flux to calculate the driver input torque, so the teeth / gaps you mentioned in post #76 (Steering locked up on freeway - the investigation begins) aren't gears you're feeling engage a tooth at a time nor is the cause of notchy steering feeling. See this US patent as a reference: US9302700B2 - Torque sensor and power steering system using the torque sensor - Google Patents
5. From post #93 (Steering locked up on freeway - the investigation begins), since you reassembled the gear back together not in the same position relative to each other from original, you'll need to clear the learned value and/or retrim the pinion position sensor (S.A.S - steering angle sensor I assume). If the after reinstalling the gear, the pinion sensor reads say 200 degrees at actual mechanical center this is likely this is causing errors in the angle hand off to the ABS brakes computer, setting the stabilitrak warning light.


Other Notes (in no particular order):
1. The tie rods are designed to be the weak point and buckle prior to a damaging load causing rack deformation, EPS housing cracking, etc. Keep this in mind if modifying or beefing up your tie rods, like adding tie rod sleeves or replacing with Heim joints.
2. If using Oetiker clamps for the boots, make sure to have the right tool and avoid damage to the boot during removal. Just buy new Oetiker clamps for reinstall if questionable.
3. EPS is reliable, there's vehicles on the road for decades now (yeah, you could claim my bias here). As with anything, once you start causing events outside the range of original design you will cause the part to eventually fail.
4. Loss of assist from EPS is controllable per ISO safety standards, there's a test for loss of assist while steering into a curve at speed and the steering wheel effort by the human driver must be below a certain torque based on vehicle classification. However, during loss of assist the steering effort by the driver is very heavy especially when vehicle is static or low speeds (less than 3-5mph). Steering a full size truck with no assist is difficult and I'm a pretty fit younger man, so I know my wife couldn't do it no assist.
5. The ball nut acts as a lead screw to translate the rotational torque from the motor into linear force. The tolerance for the balls and rack is high, therefore sensitive to contaminant intrusion.

Let me know if could clarify anything else.
Holy crap, thank you for stepping in! Tons of great info!

Locked steering:
The rough action with slightly increases effort was exactly my experience. The motor had no evidence of water intrusion, so that's good. And I confirmed the lock on the bench, which was cool.

Torque and Pinion Angle / Position Sensor Connector:
I have never touched my connectors until this investigation. In the past, I have experienced smaller episodes of the minor loss of assist at the center, but this time it was coming and going at random. I can only suspect that it was the connector wreaking havoc. I received a scanner today which ended up NOT having the ability to relearn the wheel angle for my model year 🤦🏻‍♂️🤦🏻‍♂️🤦🏻‍♂️🤦🏻‍♂️🤦🏻‍♂️, but I did find the live data showing angle was in the 200+degree range like you mentioned. A few codes were thrown, including connection loss at EBCM (Electronic Brake Control Module), and two references to "Invalid data received" from both the power steering control module and EBCM (looking at either modules' codes), one of which followed by "Not plausible". So this all makes sense. I forced her to rotate past where the assist stopped, so she probably read 800+ degrees on a system that might only see ~600 degrees. Pics of the codes below.

Other notes:
I'm well aware of the risks with heim steering. With so many folks paranoid from two instances of broken racks under very extreme conditions, I found it a challenge to see how far I could realistically take this. It likely helps that I'm much more conscious about it than others. People are cutting tie rod sleeves because of those two isolated incidents, instead of being more careful. I ditched the oetiker clamps this time, in favor of basic worm gear clamps. I make enough DIY changes to my toe, so I need quick access to the inner heim without needing to redo a clamp. I have no doubt that the systems are reliable, I just put off replacing the boots a couple weeks too late. The rack was actually quiet and smooth before the water entered. Hilariously, it's the first water that the rack has seen in a out 1.5 years. I started tinkering with new tie rod setups in May of last year. I theorize that the dirt/contaminants accumulated at the "bottom", then once the flood water made it's way in, it stirred up and pushed into the ball nut. So that's what that's called! I'm just glad it happened before the road started to get curvy.

I've done lots of troubleshooting on many things, but to have completely torn into this new system and then have an actual engineer drop facts, was awesome. I appreciate your time.

As for my next steps, I remembered that I have lifetime alignment at Firestone. Just haven't gone since I started messing with tie rods. 😂 Made an appointment with them for Camber, Caster and an SAS relearn (I'll handle my own toe, as always). Says on their appointment generator that they do the SAS relearn, so fingers crossed I can actually get it done. And for free! I'll take my disappointing new scanner with me to reset the codes if they don't do it. Eventually I wanna track down a better condition shaft and ball nut 😂, and get her back to normal. Maybe even look into building the center section brace when it comes back out. 🤷🏻‍♂️


Code pics

Mobile phone Mobile device Communication Device Telephony Gadget
Gadget Communication Device Font Mobile device Flat panel display
Blue Gadget Communication Device Mobile device Font
 

·
Registered
Joined
·
9,753 Posts
Good call on the clock spring. I definitely installed it one rotation off. When I get some motivation, I'll see if it's possible to remove the steering shaft without dropping the rack. The middle connection is easy to access from the side of the truck, and there is a good amount of throw in the slip shaft. Worst case, it's four bolts to drop the rack.
Well, the clock spring was really and after thought. My real concern is that you got the sensor on the column correct with the rack. There is no reason not too. So, what I do is lock the steering wheel at a certain point when disconnecting the rack. Then make sure it goes back the same way it came off. I bet you have it 360 deg off/wrong. Know what I mean?
You could probably use the lines on the reverse cam to center the wheel then center the rack and bolt the column back up.
 

·
Registered
Joined
·
9,753 Posts
To me this is the most important part. Thanks @JBurg540
1. The tie rods are designed to be the weak point and buckle prior to a damaging load causing rack deformation, EPS housing cracking, etc. Keep this in mind if modifying or beefing up your tie rods, like adding tie rod sleeves or replacing with Heim joints.
This stuff is so overlooked when people decide to re-engineer their truck!!!! Don't do it!
When something is hit hard enough something will break. OEM is good at this stuff. They really do engineer and test things!
 

·
Registered
Joined
·
1,863 Posts
Discussion Starter · #104 ·
Well, the clock spring was really and after thought. My real concern is that you got the sensor on the column correct with the rack. There is no reason not too. So, what I do is lock the steering wheel at a certain point when disconnecting the rack. Then make sure it goes back the same way it came off. I bet you have it 360 deg off/wrong. Know what I mean?
You could probably use the lines on the reverse cam to center the wheel then center the rack and bolt the column back up.
I think there is a certain procedure to trick it back into alignment. I pulled the battery, then lowered the rack and rotated the shaft. She was still saying I was a rotation off....🤷🏻‍♂️ Almost feel like I should have left the battery on to maintain active position. Oh well.

I have an alignment appointment with Firestone tomorrow and their website says they do the SAS relearn. At least I have the clock spring in the correct orientation to avoid possible damage.
 

·
Registered
Joined
·
9,753 Posts
I think there is a certain procedure to trick it back into alignment. I pulled the battery, then lowered the rack and rotated the shaft. She was still saying I was a rotation off....🤷🏻‍♂️ Almost feel like I should have left the battery on to maintain active position. Oh well.

I have an alignment appointment with Firestone tomorrow and their website says they do the SAS relearn. At least I have the clock spring in the correct orientation to avoid possible damage.
As long as it went back like it was you should be A ok.
Let us know how it goes.
 
  • Like
Reactions: hoooogan

·
Registered
Joined
·
86 Posts
I think there is a certain procedure to trick it back into alignment. I pulled the battery, then lowered the rack and rotated the shaft. She was still saying I was a rotation off....🤷🏻‍♂️ Almost feel like I should have left the battery on to maintain active position. Oh well.

I have an alignment appointment with Firestone tomorrow and their website says they do the SAS relearn. At least I have the clock spring in the correct orientation to avoid possible damage.
I can look into what the SAS relearn procedure is, now I'm curious to know as I may have to do this one day to my truck. Some steering gears have an absolute pinion position sensor which would just require a re-trim. Other steering gears don't have an absolute pinion position sensor and learn their position over time (and possibly in conjunction w/ brakes ABS module) and store it in memory, which would require a clear memory and relearn procedure.

Let us know how that goes.

Also @hoooogan, like your attitude and you seem to take this stuff in stride. Personally, I like learning all these nuances about our trucks too.
 

·
Registered
Joined
·
1,863 Posts
Discussion Starter · #107 ·
I can look into what the SAS relearn procedure is, now I'm curious to know as I may have to do this one day to my truck. Some steering gears have an absolute pinion position sensor which would just require a re-trim. Other steering gears don't have an absolute pinion position sensor and learn their position over time (and possibly in conjunction w/ brakes ABS module) and store it in memory, which would require a clear memory and relearn procedure.

Let us know how that goes.

Also @hoooogan, like your attitude and you seem to take this stuff in stride. Personally, I like learning all these nuances about our trucks too.
I can tell you that there is only a torque sensor on the input shaft, then the angle sensor in the column. Perhaps the motor has some sort of sensor it in? There is definitely memory somewhere. And from the sound of those codes, It could be in the EBCM or PSCM.

I saw a couple videos on folks using a scanner to reset the system. Just a matter of initiating the learn sequence(with a scanner that is actually capable), turn left to lock, right to lock, then center.

As my alignment appointment was approaching, I got a call from ADS about my rear shocks. Then it hit me, I don't have any rear shocks on the truck, which was one of the reasons for buying the scanner in the first place and not driving a twerking truck to the dealer...🤦‍♂️ Cancelled the appointment until those show up, so it might be later this week/end or early next week. Doesnt help that i'm on-call for work too, starting tomorrow.... oh life. 😐
 

·
Registered
Joined
·
86 Posts
I can tell you that there is only a torque sensor on the input shaft, then the angle sensor in the column. Perhaps the motor has some sort of sensor it in? There is definitely memory somewhere. And from the sound of those codes, It could be in the EBCM or PSCM.

I saw a couple videos on folks using a scanner to reset the system. Just a matter of initiating the learn sequence(with a scanner that is actually capable), turn left to lock, right to lock, then center.

As my alignment appointment was approaching, I got a call from ADS about my rear shocks. Then it hit me, I don't have any rear shocks on the truck, which was one of the reasons for buying the scanner in the first place and not driving a twerking truck to the dealer...🤦‍♂️ Cancelled the appointment until those show up, so it might be later this week/end or early next week. Doesnt help that i'm on-call for work too, starting tomorrow.... oh life. 😐
From what I can gather too, for the Colorados the torque sensors on the input shaft and position center is on the column. The motor also has its own position sensor for motor control purposes (look up brushless DC motor control). The position relearn sequence you described is learning the end of travel positions, typically checked/reconfirmed during final vehicle inspections at the plant. This is important for protection features so you don't damage the steering gear by slamming it into the travel stops. Like you assumed before, the code U0420-5A indicates another module is flagging the steering system rack travel exceeds the expected value range.
 

·
Registered
Joined
·
1,863 Posts
Discussion Starter · #109 ·
Well fk me. Got a bunch of excuses from Firestone. They are willing to do the alignment and SAS reset, but don't wanna touch the heims, so they "can't" do the alignment which needs to be done in order for the SAS reset to happen. Looks like I'll just throw the stock tie rods back on, get it done and swap the heims back. Fak!
 

·
Registered
Joined
·
1,863 Posts
Discussion Starter · #110 ·
Well, even though Firestone was a bag of disappointment, I sent her on a 500 mile round trip this past weekend and she did great, regardless of the stabilitrak and power steering warnings. Steering was smooth, with a tiny bit more resistance. Doing the parking lot lock to lock turns is when it will occasionally do a light studder, when I hit the perceived end of steering angle, but as long as I make it a quick motion, she continued the assist to lock. I'm definitely a little traumatized after the incident. I two handed every turn that was on a cliff, but she did flawlessly. There was a ton of cliffy turns. 😂

I'll look at swapping the tie rods sometime this week and getting the truck back in for alignment. I'm much more confident about the situation and don't feel a larger sense of urgency to resolve the angle reset. I will still get it done, but I did not find any severe, negative side effects.

Things I've noticed that are effected by the steering angle being off:
Reverse gridlines
Traction control/stabilitrak turned off
"Off-road" DIC page completely blank

Cruise control works fine. Offroad mode turns on. Haven't tried lockers or 4x4.
 

·
Registered
Joined
·
745 Posts
Well, even though Firestone was a bag of disappointment, I sent her on a 500 mile round trip this past weekend and she did great, regardless of the stabilitrak and power steering warnings. Steering was smooth, with a tiny bit more resistance. Doing the parking lot lock to lock turns is when it will occasionally do a light studder, when I hit the perceived end of steering angle, but as long as I make it a quick motion, she continued the assist to lock. I'm definitely a little traumatized after the incident. I two handed every turn that was on a cliff, but she did flawlessly. There was a ton of cliffy turns. 😂

I'll look at swapping the tie rods sometime this week and getting the truck back in for alignment. I'm much more confident about the situation and don't feel a larger sense of urgency to resolve the angle reset. I will still get it done, but I did not find any severe, negative side effects.

Things I've noticed that are effected by the steering angle being off:
Reverse gridlines
Traction control/stabilitrak turned off
"Off-road" DIC page completely blank

Cruise control works fine. Offroad mode turns on. Haven't tried lockers or 4x4.
Sounds great! You have it figured out :rolleyes:
 

·
Registered
Joined
·
1,863 Posts
Discussion Starter · #114 · (Edited)
The saga continues.

Assist went out today. Was driving then it tightened right up. But this time it was different, like what some people were reporting earlier in this thread about needing a ton of strength to steer. It wasn't locked, but it was almost like the assist was trying to keep the wheel dead straight. After muscling it to turn, the wheel would snap right back to center. Restarting the truck would clear the issue for about 20-30 seconds.

I have a major trip coming up in 2 weeks and it is solely based on taking the truck. Decided that paying for a new rack was in my best interest vs taking a gamble with the dealer. I've heard too many stories of people having their trucks stuck at the dealer for extended periods. I just don't have the time for that possibility as I am still trying to wrap up some updates before the trip. The price of a new rack is worth knowing my truck will be ready. It'll probably only take 20-30 minutes to swap the rack, and I'll have a spare for parts.

For what it's worth, I'm not mad at this. I know the damage and reassembly, significantly increased the drag/friction in the rack, and it may just be overloading the sensor and motor. I also have been running the truck without any SAS reset/relearn since it went back together. It has had the codes and lights on the dash ever since. I've logged about 2500 miles and a couple solid crawling trails like this, so not too shabby. The bad bearing noise from the ball nut was also wearing on me, so the replacement was eventually going to happen. And for the whole $10 that I spent to replace the ball bearings, she did good as a temp fix. It was never supposed to be a permanent fix.

Anyway, I should have a new rack mid week, and will reschedule an alignment to get everything reset and hopefully back to square one. I guess this also eliminated the step where I had to swap the old tie rods back on for Firestone to realign. Yup, never got around to that either.

Thanks for watching today's episode of Hogan Just Wants to Turn. 😂
 

·
Registered
Joined
·
1,863 Posts
Discussion Starter · #115 ·
New rack is in. Currently at Firestone for that long awaited alignment and hopefully successful SAS reset.

Entire replacement with several toe adjustments took about 45 min, taking my time. You can finagle the entire thing in/out without taking tie rods off, so that was nice.

Automotive tire Motor vehicle Bicycle part Bumper Asphalt
 

·
Registered
2016 Colorado WT, crew cab long bed
Joined
·
725 Posts
Firestone turned me away for 1.5” lifted Subaru. Did they actually align your truck?


Sent from my iPhone using Tapatalk
 

·
Registered
Joined
·
1,863 Posts
Discussion Starter · #117 ·
It's been a bit since I got back from Firestone, but fk those guys. They couldn't do the work last time because of the tie rods and now with factory tie rods, they won't do it because my suspension is "modified". Not sure how many different ways I can explain that it is factory height and I want factory specs. Called Chevy and got an appointment for Monday morning to do the SAS reset, then I'm reinstalling the heim setup and taking it to a specialty alignment shop to handle the alignment. Might even throw on the Dirt King alignment cams as well. Forgot I had those on the shelf.

Just bugs me that they "changed their minds" this second time around and was "just gonna do it for me" the first time. Fk them.
 

·
Registered
2016 Colorado WT, crew cab long bed
Joined
·
725 Posts
It’s a true pain getting an alignment on a modified vehicle. Everyone will deny you or charge you up the ass. Got charged way too much for my leveled truck and baby lift Subaru and my buddy just did the whole go around trying to get his leveled frontier aligned.


Sent from my iPhone using Tapatalk
 

·
Registered
Joined
·
1,863 Posts
Discussion Starter · #120 ·
It’s a true pain getting an alignment on a modified vehicle. Everyone will deny you or charge you up the ass. Got charged way too much for my leveled truck and baby lift Subaru and my buddy just did the whole go around trying to get his leveled frontier aligned.


Sent from my iPhone using Tapatalk
Ya, part of the reason that I'm stock height is because of this. But man, they freaked out this time. Mind you, this is the same place, same service rep and same alignment tech. They even mentioned the last time, but now all of a sudden, it's too modified with less modifications. They even gave me my prelim numbers last time and I know there is more than adequate adjustment to bring it into spec.

I avoided the other shop because they are usually booked out a month at a time and I can walk-in to Firestone. I literally walked in today on a completely booked day and was only there for a little over an hour. But the other shop specializes in lifted and custom offroad alignments. I just probably won't be able to get an appointment till after my trip and return from my extended stay in Colorado.
 
101 - 120 of 143 Posts
Top