Schematic Reference: Automatic Level Control Schematics

Did you perform the Automatic Level Control (ALC) Diagnostic System Check?

Go to Step 2

Go to Diagnostic System Check - Automatic Level Control

1. Turn the ignition ON with the engine OFF.
2. Listen for the ALC air compressor to activate.

Is the ALC air compressor running for more than 5 minutes?

Go to Step 3

Go to Step 6

1. Turn the ignition OFF.
2. Remove the ALC compressor relay.
3. Turn the ignition ON with the engine OFF.

Is the air compressor running?

Go to Step 4

Go to Step 5

1. Turn the ignition OFF.
2. Reinstall the ALC compressor relay.
3. Repair the short to voltage in the ALC air compressor motor control circuit.

Is the repair complete?

Go to Step 13

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1. Turn the ignition OFF.
2. Replace the ALC air compressor relay.

Is the repair complete?

Go to Step 13

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Inspect the left and right rear position sensors for damage and disconnected links.

Are any damaged sensors or disconnected links present?

Go to Step 7

Go to Step 8

Replace the damaged rear position sensor or reconnect the link.

Is the repair complete?

Go to Step 13

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1. Remove the ALC intake filter from the vehicle body. Do not remove it from the ALC air compressor or hose.
2. Using the scan tool, cycle ALC air compressor.
3. After 1 minute, stop cycling.
4. Cycle the ALC exhaust solenoid while checking to see if air is exiting the ALC intake air filter.

Is air exiting the ALC intake air filter?

Go to Step 11

Go to Step 9

1. Disconnect the air tubes from both rear shock absorbers.
2. Connect the J 22124-B ALC pressure gage between both air tubes.
3. Open the gage toggle valve.
4. Disconnect the air tube from the ALC air dryer.
5. Apply shop air to the gage schrader valve.

Is air exiting both of the air tubes at the ALC air dryer connection?

Go to Step 10

Go to Step 12

1. Turn the ignition OFF.
2. Replace the ALC air compressor assembly. Refer to Air Compressor Replacement .
3. Install the ALC intake air filter on the vehicle body.

Are all of the replacements and/or installations complete?

Go to Step 13

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1. Turn the ignition OFF.
2. Connect the scan tool.
3. Turn the ignition ON with the engine OFF.
4. Perform the ESC/ALC recalibration procedure.

Has the recalibration procedure been completed?

Go to Step 13

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Replace the air tube going from the air dryer to both rear shock absorbers. Refer to Air Tube Replacement .

Is the repair complete?

Go to Step 13

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1. Turn the ignition OFF.
2. Turn the ignition ON with the engine OFF.
3. Wait for at least 5 minutes.

Is the rear of the vehicle at trim level?

Go to Step 14

Go to Step 2

Operate the system in order to verify the repair.

Did you correct the condition?

System OK

Go to Step 2

Schematic Reference: Automatic Level Control Schematics

Did you review the ALC System Description and Operation and perform the necessary inspections?

Go to Step 2

Go to Symptoms - Automatic Level Control

1. Disconnect the auto level control sensor connector.
2. Connect a test lamp between the battery positive voltage circuit of the ALC sensor and a good ground.

Does the test lamp illuminate?

Go to Step 3

Go to Step 10

Connect a test lamp between the battery positive voltage circuit and the ground circuit of the ALC sensor.

Does the test lamp illuminate?

Go to Step 4

Go to Step 11

1. Turn ON the ignition, with the engine OFF.
2. Connect a test lamp between the ignition 3 voltage circuit of the ALC sensor and a good ground.

Does the test lamp illuminate?

Go to Step 5

Go to Step 12

Connect a 10 A fused jumper between the automatic level control exhaust solenoid control circuit of the ALC sensor and a good ground.

Does the exhaust solenoid activate and vent air?

Go to Step 14

Go to Step 6

Inspect the fuse in the jumper wire.

Did the fuse in the jumper open?

Go to Step 13

Go to Step 7

1. Leave the 10 A fused jumper connected.
2. Disconnect the ALC air compressor connector.
3. Connect a test lamp between the battery positive voltage circuit and the automatic level control exhaust solenoid control circuit of the ALC compressor.

Does the test lamp illuminate?

Go to Step 15

Go to Step 8

Test the automatic level control exhaust solenoid control circuit for an open. Refer to Circuit Testing and Wiring Repairs in Wiring Systems.

Did you find and correct the condition?

Go to Step 16

Go to Step 9

Repair the open in the battery positive voltage circuit of the ALC compressor. Refer to Circuit Testing and Wiring Repairs in Wiring Systems.

Did you complete the repair?

Go to Step 16

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Repair the open in the battery positive voltage circuit of the ALC sensor. Refer to Circuit Testing and Wiring Repairs in Wiring Systems.

Did you complete the repair?

Go to Step 16

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Repair the open in the automatic level control sensor ground circuit. Refer to Circuit Testing and Wiring Repairs in Wiring Systems.

Did you complete the repair?

Go to Step 16

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Repair the open in the ignition 3 voltage circuit of the ALC sensor. Refer to Circuit Testing and Wiring Repairs in Wiring Systems.

Did you complete the repair?

Go to Step 16

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Repair the short to voltage in the automatic level control exhaust solenoid control circuit. Refer to Circuit Testing and Wiring Repairs in Wiring Systems.

Did you complete the repair?

Go to Step 16

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Replace the auto level control sensor. Refer to Automatic Level Control Sensor and Bracket Replacement .

Did you complete the replacement?

Go to Step 16

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Replace the auto level control air compressor head. Refer to Automatic Level Control Air Compressor Head Replacement .

Did you complete the replacement?

Go to Step 16

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Operate the system in order to verify the repair.

Did you correct the condition?

System OK

Go to Step 3