Off subject - GM auto leveling suspension problem
06-19-2006, 09:42 PM
#1
Race Director
Thread Starter
Off subject - GM auto leveling suspension problem
Grasping for straws as internet search hasn't yielded much help. My daily driver 97 LeSabre with rear level control has adopted the classic 70's street racer profile with it's rear end permanently hiked up in the air. Obviously the air compressor for the rear shocks is working but something else isn't. Since so many of the members here are hands-on guys I thought I would take a chance that someone else ran into this with a GM car and successfully diagnosed it. If the post gets trounced for being off-subject I understand.
Thanks
Dan
06-19-2006, 09:58 PM
#2
Safety Car
Originally Posted by DansYellow66
Grasping for straws as internet search hasn't yielded much help. My daily driver 97 LeSabre with rear level control has adopted the classic 70's street racer profile with it's rear end permanently hiked up in the air. Obviously the air compressor for the rear shocks is working but something else isn't. Since so many of the members here are hands-on guys I thought I would take a chance that someone else ran into this with a GM car and successfully diagnosed it. If the post gets trounced for being off-subject I understand.
Thanks
Dan
My WAG is that the rear ride height sensor has gone south, and not providing feedback to the compressor.
Dave
06-19-2006, 09:59 PM
#3
Safety Car
Member Since: Nov 2004
Location: going faster miles an hour...with the radio on in browns mills new jersey
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Section 15 - 13 of your 1966 chassis service manual might help you solve your problem. I have no clue as to similarities of the two systems but the basic operating principles should be about the same. [Tried to give you a Mid-Year related answer.
]
]
06-19-2006, 10:08 PM
#4
Race Director
Thread Starter
Originally Posted by nassau66427
Section 15 - 13 of your 1966 chassis service manual might help you solve your problem. I have no clue as to similarities of the two systems but the basic operating principles should be about the same. [Tried to give you a Mid-Year related answer. ]
]Dan
06-20-2006, 06:37 AM
#6
Safety Car
My experience is with a Lincoln rear air-bag suspension.
It has a compressor, height sensor, solenoids, and air-springs (there are no standard springs on this car).
The main problem people encounter:
Air-bags develop small cracks and leak -- over time, this causes the dessicant in the compressor to saturate with water vapor and kills the compressor when it tries to pull air through the plugged-up dessicant and can't.
The cure is to replace the air-bags every 100K miles so the dessicant doesn't fill up with water.
The way the Lincoln system is supposed to work:
The compressor sucks air through the dessicant and dries the air before putting it into the air-bags.
When the height sensor calls for lowering the vehicle, the dry air is expelled out through the dessicant and takes the water vapor in the dessicant with it.
So it is a continuous cycle of the air being dryed and then the dry air drying the dessicant on the way back out.
When you have, even small, leaks, the dry air leaks out and the compressor has to draw in moist air to replace it -- that moisture is never taken back out of the dessicant because the dry air leaked. Eventually, the dessicant fills up with water and plugs.
Changing the air-bags in a Lincoln suspension is preventative maintenance -- like changing spark plugs.
Tom Piper
It has a compressor, height sensor, solenoids, and air-springs (there are no standard springs on this car).
The main problem people encounter:
Air-bags develop small cracks and leak -- over time, this causes the dessicant in the compressor to saturate with water vapor and kills the compressor when it tries to pull air through the plugged-up dessicant and can't.
The cure is to replace the air-bags every 100K miles so the dessicant doesn't fill up with water.
The way the Lincoln system is supposed to work:
The compressor sucks air through the dessicant and dries the air before putting it into the air-bags.
When the height sensor calls for lowering the vehicle, the dry air is expelled out through the dessicant and takes the water vapor in the dessicant with it.
So it is a continuous cycle of the air being dryed and then the dry air drying the dessicant on the way back out.
When you have, even small, leaks, the dry air leaks out and the compressor has to draw in moist air to replace it -- that moisture is never taken back out of the dessicant because the dry air leaked. Eventually, the dessicant fills up with water and plugs.
Changing the air-bags in a Lincoln suspension is preventative maintenance -- like changing spark plugs.
Tom Piper
Last edited by Tom Piper; 06-20-2006 at 06:43 AM.
06-20-2006, 10:52 AM
#7
Burning Brakes
Originally Posted by Plasticman
Look underneath for the link from the rear axle to the ride hgt. sensor, and see if:
1. Is it still attached at both ends?
Plasticman
1. Is it still attached at both ends?
Plasticman
06-20-2006, 03:04 PM
#8
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I had the same problem several years ago with a '97 Park Avenue.... it would inflate the rear shocks to max height and not level out. Dealer finally found that a relay under the hood that controlled the compressor was bad. Replaced the relay and it was fine after that.
06-20-2006, 05:09 PM
#9
Race Director
Thread Starter
Originally Posted by Plasticman
Look underneath for the link from the rear axle to the ride hgt. sensor, and see if:
1. Is it still attached at both ends?
Plasticman
1. Is it still attached at both ends?
Plasticman
Dan
06-20-2006, 05:11 PM
#10
Race Director
Thread Starter
Originally Posted by Red '66
I had the same problem several years ago with a '97 Park Avenue.... it would inflate the rear shocks to max height and not level out. Dealer finally found that a relay under the hood that controlled the compressor was bad. Replaced the relay and it was fine after that.
Checked the compressor, linkage, wiring, etc. Disconnected the link and ran the compressor and watched it stop when I lowered the link. But nothing releases air to lower the ride height. I found a small relay for the auto leveling system under the pass. dash and will replace it tomorrow and see what happens - hope for the best. Couldn't identify any relays under the hood that looked suspicious, but if my car once had a fuse/relay directory on the underhood cover, it's gone now so I can't tell for sure.
Thanks
Dan
Last edited by DansYellow66; 06-20-2006 at 07:36 PM.
06-25-2006, 08:49 AM
#11
Race Director
Thread Starter
Originally Posted by Red '66
I had the same problem several years ago with a '97 Park Avenue.... it would inflate the rear shocks to max height and not level out. Dealer finally found that a relay under the hood that controlled the compressor was bad. Replaced the relay and it was fine after that.
Dan
