ELC Level control 2001 LeSabre will not pump. Compressor can be jumped to run. Shocks new. Level sensor good. fuse and relay ok

Anonymous wrote the right answer.

Anonymous Jan 02, 2022

What kind of scan tool ? Will it scan all the modules on the vehicle or is it just OBD2 type ? Did you check wiring diagrams an test electrical circuits for air ride an test with a DVOM - digital volt ohmmeter ? Do you know how to test ALC relay circuits . You replaced a bunch of parts that probably were not needed (,air ride compressor, fuses and ALC relay and the compressor still won't work ) ?

Which of these does your vehicle have

Automatic Level Control
Electronic Suspension Control (ESC)
The vehicles rear leveling compressor motor is switched on and off via a compressor motor relay which is controlled by the suspension control module. The suspension control module provides a switched path to ground whenever compressor activity is required. The suspension control module continually monitors the compressor motor relay circuitry to determine if the voltage level agrees with the commanded state.

DTC C0655 Level Control Compressor Circuit

DTC C0660 Level Control Exhaust Valve Circuit

The exhaust solenoid valve is switched on and off via the suspension control module. The suspension control module provides a switched path to ground whenever exhaust activity is required and during a compressor "head-relief" sequence which occurs at compressor start-up if system pressure is lower than 68.95 kPa (10 psi). The suspension control module continually monitors the exhaust solenoid valve circuitry to determine if the voltage level agrees with the commanded state.

DTC C0711 Level Control Air Pressure Sensor Circuit

Circuit Description
The suspension control module uses a 5-volt analog air pressure sensor to determine the amount of air pressure in the automatic level control (ALC ) system. The valid signal voltage range of the sensor is 0.15-4.85 volts. The sensor signal voltage will increase and decrease within the valid voltage range as system pressure increases and decreases.


Your best bet ,take it to a qualified repair shop that knows what they are doing .

You need to check a few things. Do you ever hear the air compressor at the rear of the vehicle running?
If so, does it run continuously with the ignition on? (that will mean there is usually an air leak either in one of the rear shocks or the air lines/connectors).
If not, either the compressor, or the compressor relay, level switch and/or the fuse may be shot and each will have to be checked.

When you turn the key on, after a couple of seconds the system should cycle the compressor on for a couple seconds at least. If not, you'll need to troubleshoot if it is an electrical problem (fuse, relay, height switch/sensor, wiring in between components/bad connections) or a mechanical problem (compressor, hoses, bladder on air shocks leaking air).

There is a fuse & a relay for the Electronic Level Control/ELC also called Automatic Level Control/ALC under the back seat in the power distribution block/fuse. Switch out a relay with a similar one and check the fuse for a burnt center section.

There is a ride height sensor attached to one of the rear control arms. With the vehicle safely raised and supported, disconnect the 'link' from the sensor to the suspension arm. With the key ON and engine NOT running, push the arm on the ride height to the compressed/riding low setting. After about 15-30 seconds (it is slow to respond or it would kick on and off over every bump) the compressor should turn on and begin filling the air bladders on the rear shocks.

If the compressor still fails to come on, you'll need to unhook the harness connector at the compressor. Again, with the key ON, engine OFF, height sensor compressed connect a voltmeter to the Dark Green wire on the chassis side of the harness connector (there are four wires to the compressor. 2 wires are for the electric motor to raise the car, and 2 wires are for the Vent solenoid the releases air pressure lowers the car) and ground to see if the compressor is being told to turn on by the height sensor. If it is being commanded on and supplied electricity, and still doesn't make noise or pressure, then replace it off a similar year GM vehicle that has rear air suspension (Cadillacs, Buicks, Oldsmobile Auroras). As long as the compressors are the same, you can just remount it in your car's mounting bracket assembly and save some $$.

If the compressor comes on but the car won't rise, check the air lines to each shock from the compressor, the bladders on the shocks themselves, the filter on the compressor intake or even the vent solenoid assembly on the compressor unit has been known to leak/corrode/stick.

Good luck.

Check and make sure that the level control lever that goes to your shocks was reconnected. Might have been overlooked....Hope this helps.

1. Locate the automatic level control height sensor under the rear of the vehicle on the rear suspension support. If the back of the car is too low and will not pump up, ground pin B Yellow wire and see if the compressor will come on and the car will raise.

2. If the car does raise when pin B is grounded, check the powers and grounds to the height sensor.
3. If the powers and grounds are OK and the pump does come on and the car raises when pin B is grounded, the height sensor will need to be replaced.

4. If the car is too high and will not come down, ground pin E White wire at the height sensor to see if the car will lower.

5. If the car lowers when the White wire in pin E is grounded, check the powers and grounds to the height sensor.

6. If powers and grounds are OK and the car does lower when pin E is grounded, the height sensor will need to be replaced. Tech Tips: There are two different automatic level control systems for this car; one is without RPO F45 and one is with RPO F45. The system without F45 has an automatic level control height sensor and with F45 the automatic level control compressor is controlled by the continuously variable road sensing suspension module. Tests/Procedures: 1. Using a head lamp as a load, test the ELC height sensor power/grounds.

2. The power feeds are: Orange wire, pin C and a Brown wire, pin D.

3. The ground is pin A, Black wire.

4. Ground the White wire at the height sensor, check that the vent solenoid in the ELC compressor clicks and vents the air from the system. Author: Bill Siegmann

Dynaride means that your rear shocks have electronic level control. There is a sensor mounted to the rear suspension. If you add some luggage or persons to the car the rear lowers. The sensor senses this down movement and starts the air compressor which is mounted in under the hood (left fender area). This compressor pumps air into the rear shocks compensating the additional load, so the car remains at proper level all the time. If you start the engine with a delay of about 20 secs the compressor should run for a view seconds to build up the minimal pressure the system needs. If the engine is stopped also with some delay of 30 sec. the release valve opens to vent out all the air.

Hello: S036 concerns the road sensing suspension, in this code it tells us the electronic level control (ELC) compressor relay has a short to ground or an open circuit. Fuses to this system (2) one 10 amp in the engine compartment. The other fuse is a 30amp located in the trunk compartment. There is also a relay in the trunk compartment relay center, #2mirco relay center ELC relay "A". I hope this helps you.

Check for a fuse that indicates radio and replace it if it's burnt through or melted or discolored. The Buicks have dash controls that require expensive repairs sometimes to get the temperature controls to work so some people jump around the controls by installing a separate toggle switch that directly turns the AC unit off and on for 92 through 94 Buicks. Any AC shop can install the bypass wires.

The lines to the compressor likely have cracks or the pump isn't working. Worst case is the airbags in the shocks are shot.

elc system doesn't automatically level car