FAQ: Automatic Leveling Control (ALC) Concerns

Brian,
Thanks for posting the diagrams. I don't have the ability to do that.

No problem. Took me a while to collect them all and sort them, but I have pretty much every diagram for the 96 done. I'm eventually going to have them all up and posted, but I need to find somewhere else to host them as Picasa doesn't allow sub albums. I might have to post them all over to Flickr unless someone else has a suggestion.

Hi: Thaks to all.
I'll see if I can purge the air by way of the exhaust valve.

Ciro,
When I bought my car used I had bad shocks.
After replacing the shocks I found the compressor worked good as far as pumping them up, but they would not go back down.
At first i just disconnected the line at one of the shocks to make sure the compressor and the control switch worked.
Basically I simulated a leak to see and hear the pump working.
The next step for me was to remove the compressor and mount assembly completely from the car to find out why it wasn't exhausting the air as necessary.
I removed the compressor from the right rear fender well area by removing 2 bolts that hold up the tailpipes and the fasteners that hold the compressor assembly in the rear fender from under the car.
Once I had the unit on the bench and tested it, I could then see the exhaust port was full of corrosion and was able to clear it out using an Awl and some small drill bits.
Be carefull if you have to remove the compressor head to this on yours. Things can easily go wrong.
I'm not saying that this is the problem with yours as it could be the control unit that is on the drivers side of the car.
Actually I would recommend jacking up the back end and putting jack stands under each rear control arm. Then unhook the arm that goes to the drivers side lower control arm and move the arm up and down with the key on and see what the pump does.
There is a delay from when you move the arm to when you can expect a reaction from the compressor pump. Please keep this in mind, I forget just how many seconds the delay is, but be patient.
What you are trying to do is simulate the car having had a load put in the trunk or removed.
This is when I found my shocks would get inflated by the compressor pump but would not deflate. Then I removed the compressor assy and looked further.
Good luck and don't hesitate to ask questions as you go along if you need help.

Here is the proper torque info.

Purge it or just pull the air line off each shock. Check to make sure the self-leveling arm (on the LR control arm) didn't break and move causing the shocks to pump up and stay......

Abaddon wrote:

Purge it or just pull the air line off each shock. Check to make sure the self-leveling arm (on the LR control arm) didn't break and move causing the shocks to pump up and stay......

If the self-leveling arm on the control unit gets broken or disconnected for some reason you will most likely find that the arm will drop from gravity.
If that happens, that will simulate a car that is too HIGH and command the exhaust solenoid in the compressor head to relieve pressure, not add air.
That is if the arm drops, though.

One other thing I forgot to mention is when you do remove this arm from the lower control arm to manually operate it is that not only is there a lengthy delay (40 or so seconds) before it will either pump up the shocks (lever arm UP) but after you have commanded it to one way and have gotten a response or not, you then have to go back into the car and turn off the ignition switch and turn it back on to get the system to respond to your next command.
Also, when you are commanding the compressor to exhaust air (control arm Down) it has to be very quiet wherever your working. No wind or background noise at all, because you are listening for a very faint sound of the exhaust solenoid opening. You may or may not be able to hear the air being exhausted out if it's working normally.
HTH

I have once taken the compressor off and opened it.
the lines where full of somekind white stuff...there is a filter what can be changed? it was for taking the moisture out of the compressed air.
If it gets old it sucks the drying stuff into the lines and they get cloaked.

There is a drier assembly.

The air dryer has desiccant in it.
I guess it can find it's way into the system if something fails.
I thought about adding that desiccant dryer Assembly to my Preventive Maintenance schedule a while back but something stopped me and I can't remember right now.
It was either lack of availability or cost.????

Hi: Thank you all.
I'm going to work on her tomorrow.
Thanks again.
Ciro

Ciro, if you just want to get it down for now without worrying about anything else (since our rear springs are usually pretty high by themselves, anyway) here's the fast & dirty way out:

-Pull the ELC fuse in the right rear fuse block
-Reach into one rear wheel well and pull the spring-clip in the connector sideways to pop it off the shock... That will exhaust the whole system.

Hey guys,

I just now, for some reason, got back to reading this because now that it's warm outside, I'm going to get this stupid leveling system fixed.

I read that you can put power to the compressor wires without undoing the compressor. Great. That's the first step. If the compressor doesn't run when I put power to it on those direct wires, it's safe to assume the compressor is bad?

So after the compressor is sorted out, if it still doesn't work, I'll move on to the leveling sensor. Once that is deemed working, if the system still doesn't work, it would likely be a wiring issue?

How does this all sound as a plan of attack? The fuse and relay is good, the bad, old, but still semi-trustworthy shocks are still holding air since who knows how long ago. I guess my air lines are good enough too since my ride height hasn't really gone down at all since i bought the car.

Thoughts? Comments? I do have access to Mitchell's so I'll be consulting that. Thanks guys!

I learned a bunch in 3 minutes with only a test light and the level sensor disconnected.
That would be the first thing to do, see if there is power to 2 pins with the key on and if the compressor runs or purges by hitting the appropriate pin with your grounded test lamp

98inSFl wrote:

I learned a bunch in 3 minutes with only a test light and the level sensor disconnected.
That would be the first thing to do, see if there is power to 2 pins with the key on and if the compressor runs or purges by hitting the appropriate pin with your grounded test lamp

Basically your using your test light as a power source, Yes.?
Similar to using a "Power Probe".
If you don't have one they are the handiest replacements to a standard test light.
I still keep both though. But I find more and more use for the Power Probe and have come to reach for it first, before my aging, yet still working, Snap-On test light.

I was using the light looking for power at the sensor plug and accidentally discovered I could toggle the run relay using the test light

Z-type wrote:

...the bad, old, but still semi-trustworthy shocks are still holding air since who knows how long ago. I guess my air lines are good enough too since my ride height hasn't really gone down at all since i bought the car.

The first thing I'd do is test that assumption... I just posted this in another thread, but unlike the Cadillacs that originally used the Level Ride system, these Rivi's have quite stout rear springs. If you reach into a wheel well and remove one of the air connections, I think you'll find that the car is sitting on the springs alone, not any residual air. Just pull the metal clip out sideways and the connector will pull right off.

Then if the compressor aint working there it sits.... just squeeze the shock and you will be able to tell

Also, I don't know if you ever found a '95 schematic, but an easier way to try to run the compressor manually is to jump the contacts in the rear seat relay box... If they at least use the same relay, regardless of the circuit labels and wire colors, the terminals that feed the pump motor are the ones that connect to relay pins 87 and 30.

Hmm I like the idea of trying to jump them at the relay pins. Now, let's say i pull the relay. Looking down on where the relay was, which pins exactly am i jumping? Are they numbered? I haven't looked yet...been too busy.

Also, I noticed that the connections on my shocks are actually the threaded ones! Odd....hanging on the air line is the original clipped connector for the shocks! It's really...strange.

It does make sense to me that the rear is sitting on just springs. I never really fully inspected my shocks...they're pretty much completely useless.

however, my ultimate goal is to get the whole system working again. Im really going to try to test the compressor jumping Sunday after i take care of my fish tanks, then move on to the next step.

Thank you all SO much for the information. Couldn't do it without you guys!

From what you describe, especially the clip connectors hanging further down the tubes, the original Delco air shocks have been replaced with aftermarket units...

As for the terminal connections, I can only repeat what I said before because I don't have '95 information: If the relay has those numbered terminals, then jump the corresponding sockets in the car.

Yeah I had to assume they were aftermarket...but they're in horrible shape. Anyway, yes I understand what you're saying now about the relay. Thanks!

Oh and I'll be springing for FSM's soon...I have other issues other than this lol. I know I should have had them a long time ago but I hadn't been making much money until recently.

Will update on what I find! Stay tuned...

I got a set of brand new Delco Air Shocks in the box if ya need em. They retail for bout $300......They are the all steel kind with the air bags covered.....not exposed. Let me know if you want em.

Andrew, when you get serious about getting the FSM message me.

Well, I just got done with some testing. I am led to believe that my compressor is bad. Here goes:

First thing I did was pull the relay out and check out if there were numbered pins or not. No 87's or 30's anywhere. Just pins 3, 5, 1, and 2. So I pulled the trunk relay to see which pin got power when the relay closed....5. So I put direct power from the battery to pin 5, and as I expected, no running compressor. I then went under the car and unplugged the compressor harness by the e-brake cable - put direct power to the yellow cable, nada. No running compressor.

The compressor is rather rusty and i don't expect it works very well because of that lol. I'm going back out to pull it off right now. I'll be contacting a few of you soon probably...

EDIT: Here's what I pulled out from under the car: