GM Service Manual Online
For 1990-2009 cars only

Step

Action

Value(s)

Yes

No

Schematic Reference: Automatic Level Control Schematics

1

Did you review the automatic level control suspension system operation and perform the necessary inspections?

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Go to Step 2

Go to Symptoms - Automatic Level Control

2

Verify that the automatic level control compressor motor does not activate.

Does the automatic level control system operate normally?

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Go to Testing for Intermittent Conditions and Poor Connections in Wiring Systems

Go to Step 3

3

Inspect the LD LEV Fuse for an open.

Is the fuse open?

--

Go to Step 15

Go to Step 4

4

  1. Ensure that the automatic level control inflator air switch is in the OFF position.
  2. Turn OFF the ignition.
  3. Disconnect the automatic level control air compressor connector.
  4. Turn ON the ignition, with the engine OFF.
  5. Using a DMM, measure the voltage at the automatic level control air compressor battery positive voltage circuits.

Does the voltage measure within the specified value at both circuits?

11-16 V

Go to Step 5

Go to Step 16

5

Inspect the IGN E Fuse for an open.

Is the fuse open?

--

Go to Step 20

Go to Step 6

6

  1. Turn the ignition ON, with the engine OFF.
  2. Measure the voltage of the ignition 1 voltage circuit at the automatic level control compressor connector.

Does the voltage measure within the specified value?

11-16 V

Go to Step 7

Go to Step 19

7

Connect a test lamp from the battery positive voltage circuit to the automatic level control compressor ground circuit at the automatic level control compressor connector.

Does the test lamp illuminate?

--

Go to Step 8

Go to Step 18

8

  1. Turn OFF the ignition.
  2. Reconnect the automatic level control air compressor connector.
  3. Disconnect the automatic level control height sensor.
  4. Turn ON the ignition, with the engine OFF.
  5. Test the ignition 1 voltage circuit for voltage.

Does the voltage measure within the specified value?

11-16 V

Go to Step 9

Go to Step 17

9

Connect a test lamp from the ignition 1 voltage circuit to the sensor ground circuit at the automatic level control height sensor connector .

Does the test lamp illuminate?

--

Go to Step 10

Go to Step 14

10

Test the automatic level control inflation timer relay circuit for an open, short to ground and a short to voltage. Refer to Testing for Continuity , Testing for Short to Ground , Testing for a Short to Voltage and Wiring Repairs in Wiring Systems.

Did you find and correct the condition?

--

Go to Step 27

Go to Step 11

11

Test the automatic level control relay coil supply voltage circuit for an open, short to ground and a short to voltage. Refer to Testing for Continuity , Testing for Short to Ground , Testing for a Short to Voltage and Wiring Repairs in Wiring Systems.

Did you find and correct the condition?

--

Go to Step 27

Go to Step 12

12

  1. Turn the ignition ON, with the engine OFF.
  2. Connect a 3 amp fused jumper wire between the electronic level control relay coil supply voltage circuit and a good ground.

Does the compressor start and run?

--

Go to Step 25

Go to Step 13

13

  1. Connect a test lamp between a known good ground and the automatic level control motor relay output circuit at the automatic level control compressor relay.
  2. Turn ON the ignition, with the engine OFF.
  3. Wait 40 seconds.

Does the test lamp illuminate?

--

Go to Step 24

Go to Step 23

14

Repair the open or high resistance in the sensor ground circuit. Refer to Wiring Repairs in Wiring Systems.

Did you complete the repair?

--

Go to Step 27

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15

Repair the short to ground in the battery positive circuit. Refer to Testing for Short to Ground and Wiring Repairs in Wiring Systems.

Replace the LD LEV Fuse.

Did you complete the repair?

--

Go to Step 27

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16

Repair the open in the automatic level control battery positive circuit to automatic level control air compressor. Refer to Circuit Testing and Wiring Repairs in Wiring Systems.

Is the repair complete?

--

Go to Step 27

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17

Repair the open in the ignition 1 voltage circuit. Refer to Wiring Repairs in Wiring Systems.

Did you complete the repair?

--

Go to Step 27

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18

Repair the open or high resistance in the automatic level control air compressor ground circuit. Refer to Wiring Repairs in Wiring Systems.

Did you complete the repair?

--

Go to Step 27

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19

Repair the open or high resistance in the ignition 1 circuit. Refer to Wiring Repairs in Wiring Systems.

Did you complete the repair?

--

Go to Step 27

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20

Repair the short to ground in the ignition 1 circuit. Refer to Testing for Short to Ground and Wiring Repairs in Wiring Systems.

Did you complete the repair?

--

Go to Step 27

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21

Repair the open or high resistance in the battery positive voltage circuit. Refer to Wiring Repairs in Wiring Systems.

Did you complete the repair?

--

Go to Step 27

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22

Repair the open in the automatic level control inflation timer relay output between the automatic level control timer relay and the automatic level control sensor. Refer to Circuit Testing and Wiring Repairs in Wiring Systems.

Is the repair complete?

--

Go to Step 27

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23

Replace the automatic level control air compressor relay. Refer to Air Compressor Relay Replacement .

Is the replacement complete?

--

Go to Step 27

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24

Replace the automatic level control air compressor. Refer to Air Compressor Replacement .

Is the replacement complete?

--

Go to Step 27

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25

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

Did you complete the replacement?

--

Go to Step 27

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26

Replace the automatic level control timer relay. Refer to Automatic Level Control Relay Replacement .

Is the replacement complete?

--

Go to Step 27

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27

Operate the system in order to verify the repair.

Did you correct the condition?

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System OK

Go to Step 3