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1987-1991 Parley with regards to your 1987 to 1991 Bonneville, Olds 88 or Buick Le Sabre Please use General Chat for non-mechanical issues, and Performance and Brainstorming for improvements.

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Old 07-14-2007, 12:54 PM   #1
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Default ELC questions!!

I finally got a couple of air struts, and was finally able to get my ELC working again.
Along with the air struts, the car has brand new FE2 springs, front swaybar and bushings, and all 4 strut mounts (front bearings too) were replaced.

Man, I was driving the car last night, and this thing feels SWEET. Even with a bad alignment, it still felt great. I can only imagine the improvement once I get it lined up. That'll have to wait at least a week so the springs can settle. I got it close anyways so it won't hurt the tires.

I do have a few questions regarding the system operation.

When I turn the key on, the compressor starts up after the delay, and runs for a few seconds. The rear is filled with air as normal. But the compressor only runs for a few seconds, is it supposed to run for a longer period? Or is it not needed as I have nothing in the car?
Last night, i manually made my compressor turn on, and ran it for a little while. I then unplugged it, and the air pressire stayed in the struts. (man, i just love playing with the system ) This morning, the shocks were completly empty of air. I wonder if this is normal? It did seem to hold pressure for a while last night, and delievered a nice firm ride. It was not punishing, and actually, i think it got softer and more controlled over the rough pavement. I really like it!!!!

Another thing, my tires? They are 15 inch 205/70 r15 Goodyear Regatta 2 They ride well, but am I missing out on anything? I prolly will not upgrade to 16 inch rims and the 225/60/16 tires yet until next year. Besides, the tires that are on it will last a while anyways.

Anyways, gotta go get a few things for the car. Still gotta find a rear sway bar, which is difficult..
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Old 07-14-2007, 01:22 PM   #2
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The ELC compressor shuts on and off by a pressure actuator , not time related.

Being new shocks, they should stay up all night..Check for leaks, especially where it connects into the rear shock with some soapy water. The coupler you put into the rear shock with the catch pin in it has an O-ring. They tend to shrink and get cracks. A little Vaseline smeared in coupler can help if it the O-ring isnt split. Given the year of your car, the ELC sensor or exhaust selenoid may also be on it'* way out.

This is how the system works: i.e.... Everything you want to know but were afraid to ask about ELC, and I'm feeling gabby this AM.


The Electronic Level Control (ELC) system adjusts rear trim height in response to changes in vehicle loading. This system consists of an air compressor assembly, air dryer, exhaust solenoid, compressor relay, height sensor, air adjustable shocks and air tubing. The compressor is activated when the ignition is On and weight is added to the vehicle. The exhaust solenoid is connected directly to the positive side of the battery, allowing the system to exhaust when the ignition is Off and excess weight is removed.

When a load is added to the vehicle, the body is moved down causing the height sensor arm to rotate upward. This movement activates the internal timing circuit which, after a predetermined delay of 8-15 seconds, grounds pin No. 3, thus completing the compressor relay circuit to ground. When the relay circuit is energized, the circuit to the compressor is complete, allowing the compressor to send pressurized air to the shocks. As the shocks inflate, the vehicle body moves upward, causing the sensor arm to rotate downward. Once the body reaches its original height, the sensor opens the compressor relay circuit and shuts the compressor Off.

When excess load is removed from the rear of the vehicle, the body rises upward, which causes the sensor arm to rotate downward. This movement activates the internal timing circuit which, after a predetermined delay of 8-15 seconds, allows the sensor to complete the exhaust solenoid circuit to ground. With the solenoid energized, air exhausts from the shocks back through the air dryer and exhaust solenoid valve.

As the vehicle body lowers, the height sensor arm is rotated upward until the vehicle reaches its original height. When this height is reached, the sensor opens the exhaust solenoid circuit which prevents air from escaping.

The height sensor position is checked when the ignition is turned On. If the height sensor indicates that it is not necessary to raise or lower the vehicle, the internal timer circuit is activated. After 40 seconds, the compressor will run for four seconds. This ensures the shocks are filled with the proper residual pressure (7-14 psi). If weight is added or removed from the vehicle during this 40 second delay, the air replenishment cycle will be overridden and the vehicle will raise or lower after normal delay.

If the vehicle is staying at the maximum height without the compressor running, you have a bad ELC Height Sensor. If the compressor is running, then you have a bad relay or a short to ground.

The ELC Height Sensor is located on the left rear lower control arm. The Exhaust solonoid is located inside the compressor assembly and also acts as a safety valve to prevent too much pressure from building up.

Hope this helps.
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Old 07-14-2007, 01:28 PM   #3
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A couple corrections. The system shuts off and turns on based on the input from the level sensor, not pressure.

The sensor on the earlier (92-99 and probably the 90/91) are on the RIGHT rear control arm, not left. But he probably knows that already.

In addition, the Early 90'* ELC run without the ignition being on. The system is active at all times at least through 1993.
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Old 07-25-2009, 10:51 PM   #4
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Do you konw where can I find a schematic for the elc system on a 92 - I want to make an ignition controlled relay to only activate my elc when the car is on.
Thany you,
Chris 1992 SSe
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Old 08-05-2009, 09:40 AM   #5
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Chilton'* for your year range, or Dealer Service desk may print it out for you if you ask nicely. It depends on the dealership. Would be a great mod. Alot of older GM air ride cars become a pain when the system starts to leak a bit and it drains the battery overnight. I used to pull the air compressor connection plug when I got home on my 92 Park Ave.
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