View Full Version : leveling sensor testing procedure

08-17-10, 10:00 AM
Hello again,
Does anyone have the testing procedure for the leveling sensor?
I played with it under the car and it seems to work if I move it a lot. But the car still sags a bit after changins the shocks and the compressor ldoes not always come on after I turned the key to the on position. When I disconnect the arm of the sensor and move it up the compressor comes on and lifts the car, when I move it down the compressor delfates the shocks and the car comes down but when it is at the regular position it does not do much even if I play with the adjustment allowed by the slot.
So I am wondering if the sensor does not work properly close to its regular position or something else is wrong in the system.

08-17-10, 02:48 PM
From what you are describing (is the exact procedure described in my service manual), indicates the height sensor is operating properly. The height sensor activates the compressor after 7-14 seconds, of reading the body as being beyond an inch of normal ride height.

The next step is addressing why the body is still sagging. The sagging condition would be abnormal if the rear fenders are covering the top of your hubcaps. A severe sag should be causing the compressor to run more often, but that can be addressed later. The sag could be caused by weak or broken rear springs.

After the body sag has been addressed, the issues with the compressor not engaging at startup or at other times can be better diagnosed. It is more than likely a poor connection, being that it's intermittent, but I have the diagnostic procedure, which requires the suspension to be in proper maintenance to confirm the problem.

08-17-10, 06:56 PM
The sensor is just a switch. If it's making the car go up and down it's working. Assuming you didn't bother changing the springs yet the air shocks should still put it at the proper height, unless the new air shocks don't get as long as the old ones. How much does it really sag? Is it just your opinion or did you compare it to pictures of other ones. Like sven914 said if the hubcaps aren't buried in the wheel wells its probably sitting normal.

08-18-10, 08:00 AM
Thanks guys.
The sagging is not that much. But when I went on a trip with my GF and parents in the back over the week end the back did not seem to raise to the normal height although the compressor was activating from time to time. Besides the fact that the compressor does not seem to come on every time I start the car the system seems to do what it;s supposed to do. I did compare it to some pics and it seems a bit low. I will try to post a pic of it later today. To some pics it seems normal, to other it seems low but I am wondering if the cars that have the back end higher have the original system on or the shocks were changed with regular ones or ones with the relocated valve (no compressor needed).

08-18-10, 06:40 PM
ok so here are some pics I had.
The surface is not perfectly level so one side looks good the other one not. I guess it also depends how far away from the car the camera is and its angle



08-18-10, 08:09 PM
Looks like one side sits lower. But I think the easiest thing to do is get the shocks with the valve at the bumper. Just raise and lower when you want.

08-18-10, 09:26 PM
I checked again on a more level surface and both sides seem pretty equal and not far off normal.
I already have some stiffer springs (used) so if I go ahead with those I will probably buy some Monroe severe duty shocks. In two months I will store the car anyways so it will give me some time to think if I keep it stock or go ahead with changing springs, shocks, adding sway bars and swapping the engine

08-18-10, 09:33 PM
That is a little lower than normal, but I don't think it's anything to worry about.

If I understood your first post, you said you already changed the shocks. Did you also check or replace the air lines. They might not be able to deliver all 14psi necessary to lift the vehicle. And as for the issue with the compressor not engaging at start up, there might a an issue with the black wire that runs from the sensor to the compressor.

08-19-10, 07:40 AM
No I did not really check the lines. Actually I replaced part of them, but only the rear portion that goes to the shocks. I did not check the line that comes from the front. I should do that. I will also check that black wire

08-20-10, 03:39 PM
That's normal height. I wouldn't do anything more with it.

08-20-10, 04:54 PM
I'll say normal, too.

Here's my 81:


08-20-10, 09:24 PM
First off you have a nice Caddy, I love that red color.

And I'd say another for it "looks normal", as that's about the height of mine too.