Converting back the Z55 Air Ride Suspension

[swathdiver]

Joe, I was poking around All-Data tonight trying to help a guy with a new 2022 Sierra Denali and came across the ALC Automatic Level Control Trimset Procedure and Bumpstop Setup, saying it must be performed anytime a suspension component is replaced. I think the latter is only for Z95 but not sure. Have you seen this before?

 

[91RS]

All of them have a trim height reset.

 

[Joseph Garcia]

Joe, I was poking around All-Data tonight trying to help a guy with a new 2022 Sierra Denali and came across the ALC Automatic Level Control Trimset Procedure and Bumpstop Setup, saying it must be performed anytime a suspension component is replaced. I think the latter is only for Z95 but not sure. Have you seen this before?

Yes, I have seen them both, and I have performed the ACL procedure when I made suspension changes using the Tech 2. I have not yet found any explanation of the specific steps involved in the Bumpstop procedure, nor what model years it applies to. I even reached out to experts here in the Forum, and they were not able to provide any information on it.

If you have found an explanation of the specific steps involved in the Bumpstop procedure, please let me know.

 

[petethepug]

True. Arnott sells rebuilt OEM. Arnott also sells new units which are sourced from BWI in Mexico where the OEM are manufactured.

This info is openly available and listed as new or rebuilt accordingly, via different part numbers. Other retailers seem to be straightforward about what they sell too.

 

[91RS]

Where does Arnott say their shocks are made by BWI? They look nothing like the BWI shocks, and I have never seen that said anywhere. I just Googled Arnott and BWI and nothing came up. Safe to say, Arnott shocks are NOT made by BWI. They drive terrible compared to the OEM's in good condition so there is no way.

 

[petethepug]

I just got off the phone with Arnott to warranty one of our Audi bags. I spent about 40 min chatting with one of the long term salty’s there.

Clearing up the specs on z55 & z95 struts and manufacturing came up. Yes, they get their magnetorheological fluid for rebuilding cores & new z95 struts from BWI. z55 or Autoride are filled with hydraulic fluid / oil but still an active shock.

That’s the 411 I’m sharing from the horse’s mouth. I’ve got no ponies in the race for promoting or discrediting them. If there’s some snake oil in what they’re saying let’s post up the facts to back things up. Pics, stats, sources besides 3rd party stories. Again, I’ve got no dogs, ponies or interest in this except verifiable info.

 

[91RS]

I’ve never looked, installed, or serviced their Z95 shocks but they do indeed look just like the OEMs based on the picture, so I’ll give you that one, but otherwise, I stand by what I’ve always said. I’ve driven tons of these trucks since they were new and I know how they are supposed to feel and the Arnott isn’t it. And don’t misunderstand what I’m saying, I’m not saying OEM is the only thing that’s good. There are other quality shocks out there but they’re not cheap. I fully support the Atomic Fab/Viking coilovers and shocks and Bilstein 5100 shocks. I also believe the Fox coilovers are great but I’ve only driven one truck with them.

 

[HACK BLOCK]

Update and Solution

I reprogrammed the existing ESCM, and that did not change the response of the 4 Damper Actuators, as they still predominantly ranged between the 0% - 20% settings on my dirt test road. The process to re-program the ESCM was another separate challenge, and I've created a separate thread to discuss that experience (Migration from ACDelco TIS to GM Techline Connect for Tech 2 Users). As such, I removed the existing ESCM and I replaced it with a new ESCM, and then I programmed it to my truck. The old ESCM literally came apart from its frame from corrosion, as I removed it.

The response of the Damper Actuators changed dramatically with the new ESCM, with the range increasing to the full 0% - 95% settings range. In addition, I saw each Damper Actuator fluctuating on its own, rather that all 4 Damper Actuators essentially fluctuating together, as I had with the old ESCM. The movements within this extended range are not as dramatic as the test logged by @George B , and still show more 20% setting than any other setting number, other than 0%, but I believe that the reduced fluctuations are a result of my Hellwig sway bars, which permit very little roll of the truck. I noticed on my dirt road tests that the steering angle, the tilt/roll, and the lateral acceleration of the truck in cornering are large components of what drive the change in the solenoid office settings in the Damper Actuators.

So, at this time, I believe that I have successfully completed the conversion back to the OEM Z55 electronic/air suspension, and I thank all of you who participated virtually on this project and shared your knowledge and sage advice with me.

I'm noticing this problem now after my new rears, nothing higher than 20%. should I just go straight for a new ESCM?

 

[Joseph Garcia]

I'm noticing this problem now after my new rears, nothing higher than 20%. should I just go straight for a new ESCM?

The main question here is, while driving on a bumpy and/or winding road and monitoring the live data with your scanner, do all 4 dampers appearing to fluctuate on their own, particularly right versus left, as apposed to all 4 fluctuating in exactly the same manner at the same time?

Do you have a tow/haul mode on your truck, if yes, how to the actuators fluctuate in that mode?

 

[George B]

@Joseph Garcia what front suspension codes do you have?