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If I can share this link, yes the gas gauge was also acting weird since I got the car, and the wiper sprayer quit. Sometimes the auto wipers will come on in clear sunny weather too. I see this SAM and also issues of the CAN BUS..which Im needing to look into.

These make sense with the error codes Im getting and not clear on their meaning.

If there's no signal from the height sensor then that would explain why it won't pump up to ride height. It could also be that the plug is dirty or wiring to the sensor is damaged. It's not particularly well protected. Going from memory the sensor is is just slightly toward the driver side bolted to the aluminum subframe.

When I get home tonight I'll take some screen shots of the foxwell with the height sensor info.

If you're getting error codes for the suspension then the computer is probably fine.

The foxwell is not the most intuitive scan tool in the world.

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Reading further about the SAM I believe this is what you are calling the suspension computer? Signal Aquisition Module which coordinates a lot of electrical functions and I have other issues such as a finicky fuel level indicator, sometimes goes off or indicates full at random. Then comes back. This also is a bad SAM symptom, and it appears to be basically the rear fuse box and relays with the printed circuit board and whatever chips are involved. And they say this can be damaged by bad battery replacement, and I find a new interstate battery installed, by the PO..who was a poor mechanic by his own admission. And there are other gremilins too.

I will read more codes in the morning and I now find what I supposed was the air pump cycling is actually the sound of the SBC brakes booting up on unlocking the car. I find this system needs a new battery and the controller appears to have errors. Lots to do! But the air system is great now that I was able to 'hot wire' the pump to an independent power source and inflate the struts. No leakdown!

One feature of the Arnott pump I like is the push-in automatic air line seal which has no threaded compression nut and ring, those can leak and corode and theyre tough to fit well in tight spaces..Its a solid little component.

I'm not sure you're in the right menu.

Go:
Control units > chassis > suspension > active test or live data

That's where you can see the position of the sensor and manipulate the suspension up and down. The suspension computer is its own separate module mounted underneath the passenger floorboard. It is not the SAM.

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Okay yes, I see these computers for sale but nothing on the foxwell menu besides the SAM, and mine is showing faults that affect the washer pump and headlight and it also has a gas gage gremlin. So its great to have the foxwell NT520 to troubleshoot these faults. It shows several SAM units but all with the same fault and I suspect its reading the same unit over in each case. Nothing about the suspension computer on the menu.

But I see these for sale although I dont see this computer mentioned in any repair guides. Youre right its likely damaged in my car and not functional. Not outrageously expensive. But replacement likely requires a programming installation.

I do get function control over the air release valves in the system and tried the air release, heard no hissing, but the shocks went down about an inch when I tried the function. And the compressor test doesn't work. I get a normal ride height indication now but the old low rear end message comes back even though its now high after I manually pressurized the system. It gives a left/right control function on the shocks but it seems to just affect both at the same time equally.

And I need to replace the SBC battery as well. It shows low voltage or bad connections and its indeed crusty looking. The ECU codes mentioned above were actually SAM codes Im now seeing. The ECU passes OK with codes cleared and do not come back.

So Im running the system on manual inflation to the point the relief valve pops which gives a great ride, firm like an SUV and what I wanted. Does not bleed down unless I do the release air function in testing, which I did. Now Ive got to pressurize it up again.

Now researching the procedures to install a new suspension computer and thanks again tjts1 for the pointers..(as well as getting that SAM unit repaired/replaced. Clearly messed up )

Do you have the key in position 2 and going through the drill down menu manually? The SAM modules are in a completely different part of the drill down menu and it has nothing to with diagnosing the air suspension.
https://imgur.com/a/cbc7v9A

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where did I read the SAM collects data from nearby sensors and communicates with the other control units, like the ride height indicator. Of course Im getting a good ride height indication now but still if the SAM which has issues was in the loop, it would possibly be an issue. I see this SAM has high amp links which can melt out leaving circuits with no power supply.. Probably as you say the suspension computer is the issue, and I get no communication with the compressor although I CAN communicate with the control valves to fill or empty the struts.

(Yes Ive been through all the menus with key on.)

It seemed to make no diff which strut one fills or empties, it appears to affect both equally. It seems like the way the foxwell identifies several SAM units, left right and rear and reads the same codes on all of them. Its just the rear..

Thanks for the link on the foxwell tjts1 and Im about to remove that suspension computer and check for any obvious damage. Very likely this is the culprit but I find no service or troubleshooting references to the part, just lots of used ones for sale..

The car just drives great with the air struts completely full and compressed to the system limit! I love it..stiffer ride and sits more level and handles roughness of roads really well in this condition.

Ive read extensive chats on MBworld and BenzWorld and some are very detailed with photos and lots of great information that the official data says is wrong in order to sell parts when a hose clamp repair can easily save the system (accumulator leaks) but nobody includes mention of that suspension computer. Im looking forward to getting to the bottom of this!

Those links are likely shunts for measuring current and not primarily designed as a fuse.

If you are running the compressor until the safety relief pops, that stresses the system beyond typical operating limits.

Thanks SL..I'll be careful..

I just love the great ride fully compressed. Hopefully the relief valve is set where it will keep the system safe from damage. Im not sure if the pump relief valve is actuating electronically. Could be it is. I do have that connected to the system, but not the power leads.

And there are lots of shop reports of getting the SAM unit repaired, replaced and a host of issues resolve as a result. I know I have several related and without the exact details, just noticing the connectors feeding into the suspension control module it takes inputs from a myriad of sources, and most of these units are totally integrated with the whole car and affected by speed and ride height and more inputs than will fit on ten pages. All through the CAN bus, right? And my foxwell cannot get into this because of the bad SAMs..

tjts1 is likely correct, its the suspension module but it Could Be that the SAM inputs cause the module to lose power. And yes, probably shunts and yet they do burn out given an overload which I definitely did have..Stuck relay and the fuse failed to blow..
and need repaired or replaced so that various equipment can get power.

In view of the many compressor pump issues we read about (there was even a class action lawsuit) Im seeing that 40 amp should be a 30 or maybe even less! This is a change I will make once my electronics are working properly again.

https://www.youtube.com/watch?v=W2NbMdtKHvU

also many other cases of related power loss from bad SAM, Im having a headlight and wiper washer and at times, gas gage loss. Then back again. It could be a bad power supply connection to the SAM, low voltage. (one of the foxwell codes read) Or this AND a burned link. If its not one thing, its two.

Scanning through the Control Units menu and reading codes and getting data, one significant issue is "Cannot communicate with the Special Vehicle Multifunction Control Module." So this unit may be de-powered or malfunctioning.

Most of my SAM codes cleared and did not return, but still have no wiper washer and the headlight issue, possibly due to bad components.

The car needs a good thorough electronic troubleshooting and repair. Probably beyond the scope of the foxwell NT520..

The safety relief , using good design practice , is a straight mechanical device that generally consists of a seat , ball and spring. This is the last line of defense against over pressurization. A service manual should give typical operating pressure and relief pressure.

Running the cars compressor against the safety relief is the same as bridging the contacts on a shop air compressor and running it until the safety vents.

So re "bridging the contact points" Id say not really. When you bridge the points the pump would continue. I just ran it until the relief popped and then shut off the pump. I would NEVER bridge the points. Except to test to see if power were available or to test pump operation momentarily.

All thanks for the precaution. In my limited knowledge systems are designed with a safety margin often 30 to 50% more than max operation stress..Aircraft or auto or construction...

So about the system, I did find the fuse under the passenger footwell on the blue dot circuit was bad. Its impossible to see them but I managed to pop the plastic door off and checking with a meter is clearly bad. Just hoping to find a local replacement.

I see lots of chats referring to the Suspension control module and photos and after plulling the floor totally out there is no such module as pictured in my car. It could be this is for the adjustable or the damping control features and mine doesnt have that. All the modules I can find and look up are listed as transmission control modules.

And those fuses take a CROWBAR to get them out. Probably justified with the high amps. Tiny screwdriver under and needle nose above..Anyway Im pretty sure this will renew the system to totally automatic function and that Arnott compressor is a great replacement part. They tell me it may run one hour continuous use without damage. But this would drain most batteries..Anyway no leaks in my shocks or system. It stays up for days without adding pressure. No bleed down..And many of these leaks one finds in the reports are a bad fitting here or there. Repairable with hose clamps or epoxy. I feel the air shocks are getting a bad rap undeserved.

PS Prior to this step I did test for continuity from the actuation relay to the pins at the compressor and also from the other pin to ground. So I know the power leads to the compressor are good, there is a service bulletin out regarding vipration damage to this wiring.

Hope this helps anyone with similar issues! (several helpful chats found on the Just Answer archives) Even a wiring diagram..and no, the SAM has no input to the suspension. tjts1 was right about that..

Okay happy ending, the compressor comes on in response to the foxwell scanner and also on starting. Automatically adjusted to height and stopped. But Im not sure the scanner can adjust the ride height although it seems to read the height angles and it can add or release air from either rear shock. Probably requires a Star system to do that function..

tjts1, if you find you can adj the ride height with the scanner please tell us!

Yes you can adjust the suspension up and down with the foxwell. I'm on vacation so I can't look at it at the moment but it's in there in one of the drill down menus.

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