GM Service Manual Online
For 1990-2009 cars only
Makes 🢒 Oldsmobile 🢒 2001 🢒 Silhouette Ext. 🢒 Suspension 🢒 Automatic Level Control 🢒 Automatic Level Control Compressor Motor Does Not Activate

Step

Action

Value(s)

Yes

No

DEFINITION: The ALC compressor motor does not activate when the air inflator switch is turned on.

1

Did you review the Automatic Level Control System Description and Operation and perform the necessary inspections?

--

Go to Step 2

Go to Symptoms - Automatic Level Control

2
  1. Turn ON the ignition, with the engine OFF.
  2. Turn ON the air inflator switch.

Does the ALC air compressor operate normally?

--

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

Go to Step 3

3

Inspect the ELC/TRAILER fuse.

Is the ELC/TRAILER fuse open?

--

Go to Step 19

Go to Step 4

4

Inspect the PWR QTR VENT fuse.

Is the PWR QTR VENT fuse open?

--

Go to Step 20

Go to Step 5

5
  1. Disconnect the ALC air compressor connector.
  2. Measure the voltage between the battery positive voltage circuit and ground.

Does the voltage measure near the specified value?

B+

Go to Step 6

Go to Step 21

6

Measure the voltage between the other battery positive voltage circuit and ground.

Does the voltage measure near the specified value?

B+

Go to Step 7

Go to Step 21

7
  1. Turn ON the ignition, with the engine OFF.
  2. Measure the voltage between the accessory voltage circuit of the ALC air compressor connector and a good ground.

Does the voltage measure near the specified value?

B+

Go to Step 8

Go to Step 22

8

Measure the voltage between the accessory voltage circuit and the ground circuit of the ALC air compressor connector.

Does the voltage measure near the specified value?

B+

Go to Step 9

Go to Step 23

9
  1. Turn OFF the ignition.
  2. Disconnect the ALC air inflator relay connector.
  3. Measure the voltage between the battery positive voltage circuit of the ALC air inflator relay connector and a good ground.

Does the voltage measure near the specified value?

B+

Go to Step 10

Go to Step 24

10

Measure the voltage between the battery positive voltage circuit and the ground circuit of the ALC air inflator relay connector.

Does the voltage measure near the specified value?

B+

Go to Step 11

Go to Step 25

11
  1. Disconnect the ALC sensor connector.
  2. Connect a 10 A fused jumper wire between the battery positive voltage circuit and the ALC relay coil supply voltage circuit of the ALC air compressor connector.
  3. Measure the voltage from the ALC relay coil supply voltage circuit of the ALC air inflator relay connector to a good ground.

Does the voltage measure near the specified value?

B+

Go to Step 12

Go to Step 26

12

Measure the voltage from the ALC relay coil supply voltage circuit of the ALC sensor connector to a good ground.

Does the voltage measure near the specified value?

B+

Go to Step 13

Go to Step 26

13
  1. Disconnect the jumper wire from the battery positive voltage circuit and the ALC relay coil supply voltage circuit of the ALC air compressor connector.
  2. Connect a 10 A fused jumper wire between the battery positive voltage circuit and the ALC height sensor circuit of the ALC air inflator relay connector.
  3. Measure the voltage from the ALC height sensor circuit of the ALC sensor connector to a good ground.

Does the voltage measure near the specified value?

B+

Go to Step 14

Go to Step 27

14
  1. Reconnect the following connectors:
    2. • The ALC air compressor connector
    • The ALC air inflator relay connector
    • The ALC sensor connector
  2. Disconnect the air inflator switch connector.
  3. Turn ON the ignition, with the engine OFF.
  4. Measure the voltage from the ALC inflation timer relay coil control circuit of the air inflator switch connector to a good ground.

Does the voltage measure near the specified value?

B+

Go to Step 15

Go to Step 16

15
  1. Turn OFF the ignition.
  2. Connect a 10 A fused jumper wire between the ALC inflation timer relay coil control circuit and the ground circuit of the air inflator switch connector.
  3. Turn ON the ignition, with the engine OFF.

Did the ALC air compressor activate?

--

Go to Step 29

Go to Step 17

16

Test the ALC inflation timer relay coil 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 32

Go to Step 28

17

Test the ground circuit of the air inflator switch for an open. Refer to Circuit Testing and Wiring Repairs in Wiring Systems.

Did you find and correct the condition?

--

Go to Step 32

Go to Step 18

18
  1. Turn OFF the ignition.
  2. Remove the ALC air compressor relay.
  3. Connect a 10 A fused jumper wire between the battery positive circuit and the compressor signal circuit of the air compressor relay connector.
  4. Turn ON the ignition, with the engine OFF.

Did the ALC air compressor activate?

--

Go to Step 30

Go to Step 31

19

Repair the short to ground in the battery positive voltage circuit. Refer to Wiring Repairs in Wiring Systems.

Did you complete the repair?

--

Go to Step 32

--

20

Repair the short to ground in the accessory voltage circuit. Refer to Wiring Repairs in Wiring Systems.

Did you complete the repair?

--

Go to Step 32

--

21

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

Did you complete the repair?

--

Go to Step 32

--

22

Repair the open in the accessory voltage circuit of the ALC air compressor. Refer to Wiring Repairs in Wiring Systems.

Did you complete the repair?

--

Go to Step 32

--

23

Repair the open in the ground circuit to the ALC air compressor. Refer to Wiring Repairs in Wiring Systems.

Did you complete the repair?

--

Go to Step 32

--

24

Repair the open in the battery positive voltage circuit of the ALC air inflator relay connector. Refer to Wiring Repairs in Wiring Systems.

Did you complete the repair?

--

Go to Step 32

--

25

Repair the open in the ground circuit of the ALC air inflator relay. Refer to Wiring Repairs in Wiring Systems.

Did you complete the repair?

--

Go to Step 32

--

26

Repair the open in the ALC relay coil supply voltage circuit. Refer to Wiring Repairs in Wiring Systems.

Did you complete the repair?

--

Go to Step 32

--

27

Repair the open in the ALC height sensor circuit. Refer to Wiring Repairs in Wiring Systems.

Did you complete the repair?

--

Go to Step 32

--

28

Replace the ALC air inflator relay. Refer to Automatic Level Control Relay Replacement .

Did you complete the replacement?

--

Go to Step 32

--

29

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

Did you complete the replacement?

--

Go to Step 32

--

30

Replace the ALC air compressor relay.

Did you complete the replacement?

--

Go to Step 32

--

31

Replace the ALC air compressor. Refer to Air Compressor Replacement .

Did you complete the replacement?

--

Go to Step 32

--

32

Operate the system in order to verify the repair.

Did you correct the condition?

--

System OK

Go to Step 3