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 inflator fill valve is inoperative.

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

  1. Turn OFF the ignition.
  2. Disconnect the automatic level control inflator switch.
  3. Disconnect the automatic level control solenoid valve.
  4. Connect a test lamp between the ground circuit of the automatic level control inflator air switch and a battery positive voltage circuit.

Does the test lamp illuminate?

--

Go to Step 4

Go to Step 12

4

Connect a test lamp between the ground circuit of the automatic level control solenoid valve and a battery positive voltage circuit.

Does the test lamp illuminate?

--

Go to Step 5

Go to Step 12

5

  1. Turn ON the ignition, with the engine OFF.
  2. Connect a 3 amp fused jumper wire between the automatic level control reset signal circuit of the ALC inflator air switch to the ground circuit of the ALC inflator air switch.

Does the automatic level control air compressor pump run?

--

Go to Step 15

Go to Step 6

6

Connect a 3 amp fused jumper wire between the automatic level control relay coil supply voltage circuit of the automatic level control timer relay to the ground circuit of the automatic level control timer relay.

Does the automatic level control air compressor pump run?

--

Go to Step 7

Go to Step 13

7

  1. Ensure that the jumper wire remains connected.
  2. Measure the voltage from the automatic level control inflator solenoid valve supply voltage circuit of the automatic level control solenoid valve to a good ground.

Does the voltage measure within the specified value?

11-16 V

Go to Step 9

Go to Step 8

8

  1. Ensure that the jumper wire remains connected.
  2. Measure the voltage from the automatic level control inflator solenoid valve supply voltage circuit of the automatic level control timer relay to a good ground

Does the voltage measure within the specified value?

11-16 V

Go to Step 11

Go to Step 16

9

Measure the resistance of the automatic level control solenoid valve.

Does the resistance measure within the specified range?

20-100 ohms

Go to Step 10

Go to Step 17

10

  1. Turn the ignition OFF.
  2. Disconnect the ALC timer relay.
  3. Connect a test lamp between the automatic level control reset signal circuit of the automatic level control timer relay and a battery positive voltage circuit.

Does the test lamp illuminate?

--

Go to Step 14

Go to Step 16

11

Repair the open in the automatic level control inflator solenoid valve supply voltage circuit. Refer to Wiring Repairs in Wiring Systems.

Did you complete the repair?

--

Go to Step 18

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12

Repair the open in the component ground circuit. Refer to Wiring Repairs in Wiring Systems.

Did you complete the repair?

--

Go to Step 18

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13

Repair the open in the automatic level control relay coil supply voltage circuit. Refer to Wiring Repairs in Wiring Systems.

Did you complete the repair?

--

Go to Step 18

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14

Repair the short to ground in the automatic level control reset signal circuit. Refer to Wiring Repairs in Wiring Systems.

Did you complete the repair?

--

Go to Step 18

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15

Replace the automatic level control inflator air switch. Refer to Automatic Level Control Inflator Air Switch Replacement .

Did you complete the replacement?

--

Go to Step 18

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16

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

Did you complete the replacement?

--

Go to Step 18

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17

Replace the automatic level control solenoid valve. Refer to Automatic Level Control Solenoid Valve Replacement .

Did you complete the replacement?

--

Go to Step 18

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18

Operate the system in order to verify the repair.

Did you correct the condition?

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System OK

Go to Step 3