LS400 Air Suspension

1990 LS400 250,000 mi - electronic air suspension

I realize the electronic air suspension is an issue on early LSs. I have replaced one air unit (rear) a few months ago. The car performed well for a few months but now the suspension is acting up.

The car will hold the suspension correctly for several days/weeks and ride great. The suspension will (ususally) be at the same height when left parked overnight.

But the car may drop in the rear to the ground while driving or parked. When the car drops, the height indicator (on dash) remains in the one position and does not respond the height switch. If indicator reads "HI", indicator will continue to read HI even with switch in normal.

The ON/Off switch in the truck seems to have no effect when the car drops

I have noticed a hissing noise coming from the driver rear tire on those instances when the car is dropping after parking. The ride may come right back up when the car is started.

At this point the suspension is unreliable and I need to make a decision. Should I continue to replace the bad air suspension parts or go with a non-air aftermarket suspension system. I have replaced one rear unit.

Thx Chip L

Reply to
Chip L
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I would try to find out where the hissing sound is coming from. The problem could be as simple as a loose or leaky connection.

Reply to
Ray O

Thx Ray. Do you know where the specific location of the Air Suspension computer/controller is located?

Chip L

Reply to
Chip L

Chip,

Sorry, I do not know where the air suspension computer is located. Since the system is designed to keep the car level, it probably has to have a means of sensing the vehicle's attitude, either through a separate sensor or one built into the computer. Most of the car's computers are located either under the dashboard or in the driver or passenger side kick panels. I beleive there is also a computer under the center console.

Reply to
Ray O

Thx Ray. I traced it tonite. The air suspension computer and relay are located above the CD changer in the truck on the passenger side.

Reply to
Chip L

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