Steering Angle Sensor - what's it do?

[MultiVAC]

I am planning to replace my lower steering bearing soon to solve some clunking. Underneath the dash, its the green plastic housing that's slotted into the bottom of the steering column. I did some research, watched a few videos and I was surprised to see I have a steering angle sensor connected to it?

As far as I thought, this was pre99 variable steering or a later stabilitrak thing. I found vague mention online that maybe it's wired to abs or maybe autoride? Mine does have 'autoride-lite' no compressor, but has the adjusting shocks and ride height sensors. I've already disabled the autoride computer when I swapped to regular bilsteins. Id rather leave it on the shelf when I do the bearing if it does nothing, if anyone knows.

 

[ORVietVet]

The bearing is not connected. The steering shaft needs to be disconnected for the bearing replacement and if you do not stabilize the steering wheel when you do this, the steering wheel will free wheel and damage the SAS. If you have not done that bearing before, it will be easier if you remove the seat and lay under there to gain access. The reach in to do that work is a PITA when reaching under there. May want to do a new brake light switch while under there. If you have not done already, the roller bearings in the end of the new bearing collar, will pop out and you will see minimal grease. The bearing cage easily pops out and can smear more silicone grease on that and pop back in. Again, if have not done before, I recommend watching several you tube videos of the process. I mean it when I say, PITA until you have done a few. While in there, check your brake pedal pivot bushing for replacement. I have a thread here about that.

 

[MultiVAC]

Thanks for the heads up, yeah I was reading about using the seatbelt to hold it steady.

So, I was only able to find one video of it on a gmt800, but this is the sensor I see in the back of my lower bearing.

In all my other video-watching for how to swap that bearing, the sensor hasn't been there, here's it without the sensor from this video.
This is why I was surprised to see it on mine... and sort of confused what it's doing there?

 

[ORVietVet]

The TRQ video is new to me. I do not see those sensors on my vehicles. I would have to research more.

 

[ORVietVet]

Looks like just another piece to be very careful about when doing the bearing. Again, a PITA.

 

[MultiVAC]

Hmm yeah, its a mystery to me. I think I'm going unplug it and see if any codes throw. I'd like to try and come up with a more HD bearing replacement, I've read the replacements last <10k miles.

I found this company lists these HD models, with sensor vs/ without, ~$100
https://www.wolffeng.com/store/p16/GM109SS_Lower_Steering_Column_Bearing_WITH_Sensor_Housing.html
https://www.wolffeng.com/store/p14/GM109SS_Lower_Steering_Column_Bearing_WITHOUT_Sensor_Housing.html


I sort of wanted to document making my own using a ~$20 sealed flange bearing and a $10 shaft camp off McMaster-Carr that anyone could replicate. But to figure out a way to remount the sensor probably means a one-off 3d print.

 

[ORVietVet]

Hmm yeah, its a mystery to me. I think I'm going unplug it and see if any codes throw. I'd like to try and come up with a more HD bearing replacement, I've read the replacements last <10k miles.

I found this company lists these HD models, with sensor vs/ without, ~$100
https://www.wolffeng.com/store/p16/GM109SS_Lower_Steering_Column_Bearing_WITH_Sensor_Housing.html
https://www.wolffeng.com/store/p14/GM109SS_Lower_Steering_Column_Bearing_WITHOUT_Sensor_Housing.html


I sort of wanted to document making my own using a ~$20 sealed flange bearing and a $10 shaft camp off McMaster-Carr that anyone could replicate. But to figure out a way to remount the sensor probably means a one-off 3d print.

The steering position sensor is an important part of the StabiliTrack Electronic Stability Assist system, which is a sophisticated GM-designed system to improve vehicle stability and steering feel. The system includes a 'steering wheel position sensor,' which has one important function:

• The steering position sensor monitors the angle of the steering input in degrees, and reports that information to the ECU (the main computer in the vehicle)
• The ECU then activates or deactivates something called the Electronic Variable Orifice (EVO), which basically controls the flow of fluid in the power steering system, effecting the amount of 'boost' you get from the steering system.

The intent of this entire system is to provide more boosted steering at slow speeds, and less boost at higher speeds.

The sensor plays a big part in ensuring predictable steering, and if it wears out that can lead to some serious problems, potentially even loss of control over steering.

 

[MultiVAC]

The steering position sensor is an important part of the StabiliTrack Electronic Stability Assist system, which is a sophisticated GM-designed system to improve vehicle stability and steering feel. The system includes a 'steering wheel position sensor,' which has one important function:

• The steering position sensor monitors the angle of the steering input in degrees, and reports that information to the ECU (the main computer in the vehicle)
• The ECU then activates or deactivates something called the Electronic Variable Orifice (EVO), which basically controls the flow of fluid in the power steering system, effecting the amount of 'boost' you get from the steering system.

The intent of this entire system is to provide more boosted steering at slow speeds, and less boost at higher speeds.

The sensor plays a big part in ensuring predictable steering, and if it wears out that can lead to some serious problems, potentially even loss of control over steering.

So I was thinking it was traction control, but everything I found suggests I don't have any version of it.
I believe "EVO" was 97-99, My owners manual suggests stabilitrak for GMT800 was only on "AWD" 1500 Suburban/Yukon/Tahoe/Escalade with a button either by the radio or where the t-case controls goes. I have no traction control button, which I think is normal given I've got 4wd and G80.

I unplugged the sensor for just a minute, nothing yet ... but didn't put any miles on it today.

 

[ORVietVet]

So I was thinking it was traction control, but everything I found suggests I don't have any version of it.
I believe "EVO" was 97-99, My owners manual suggests stabilitrak for GMT800 was only on "AWD" 1500 Suburban/Yukon/Tahoe/Escalade with a button either by the radio or where the t-case controls goes. I have no traction control button, which I think is normal given I've got 4wd and G80.

I unplugged the sensor for just a minute, nothing yet ... but didn't put any miles on it today.

Does the power steering pump have the pressure valve on it or in a line with that valve in it?

 

[MultiVAC]

Does the power steering pump have the pressure valve on it or in a line with that valve in it?

Taken from below, I believe all the lines are straight in or out, don't see a solenoid.

 

[ORVietVet]

But, does one of the lines have a valve or switch in it? The way I understood the SAS explanation is that it is for the power steering valving for engine speed or steering stability control. Signs of that would be in the power steering system or on the dash.

 

[MultiVAC]

Ok I maybe I missed it, but I followed the lines and I really don't see anything. I think if there were something, it would have to be hidden in the hydroboost unit or gearbox itself.



Hmm the difference in deleted vs EVO for 97-99 look like this supposedly, not that that would really matter for gmt800s / 2004.

 

[ORVietVet]

I really am confused that my 2004 Silverado, being a K2500HD and does not have the SAS and your 2004 Suburban being a 3/4 ton, does have the SAS. More digging required here.

 

[MultiVAC]

Weird right? I feel like maybe it's not in use

 

[ORVietVet]

Maybe a steering column swap at one time? Is there and RPO code for it?

 

[MultiVAC]

I sort of doubt it, looks pretty factory to me. I did see people talking about the JL4 code, but nope.
Got JF4 - Power Pedals, JH6 - 4 Wheel disc

Got my build sheet from GM a couple years ago.

 

[ORVietVet]

What RPO code is for EVO or StabiliTrac?

 

[someotherguy]

I *think* Stabilitrak is RPO JL4. Pretty sure there's not one for EVO which wasn't an option, it was standard equipment beginning in 1997 GMT400's.

It makes sense to me now why there are those large slots in the plastic for the lower column bearing, since that sensor fits right into them. Haven't seen one before but I've only done the lower column bearing on our 2 '06 SS's.

Richard

 

[someotherguy]

I really am confused that my 2004 Silverado, being a K2500HD and does not have the SAS and your 2004 Suburban being a 3/4 ton, does have the SAS. More digging required here.

From what I can see in the application list on GMpartsgiant, the sensor was only used in some SUV's, no pickups are shown on the list (not that those lists are always a reliable source of info.) - https://www.gmpartsgiant.com/parts/gm-sensor-26104070.html

I wondered if it's part of the RPO Z55 Autoride system, but you wouldn't think so as that's just the adjustable shocks that are dependent on height sensors at each wheel.

The references I found to the steering position sensor appear to be related to Stabilitrak as suspected (failed sensor results in "Service Stabilitrak" message, but I don't see that on his build sheet. https://www.tahoeyukonforum.com/search/2548449/?q=steering+position+sensor&o=relevance

Richard

 

[MultiVAC]

From what I've read, yeah stabilitrak should be synonymous with the JL4 - "Active Brake Option"

I think I can check is to see if the rear wheels share the same brake circuit or if they have their own like with JL4. There also would be wheel speed sensors on the rear no?