GM Service Manual Online
For 1990-2009 cars only

Step

Action

Value(s)

Yes

No

1

Did you perform the ALC Suspension System Check?

--

Go to Step 2

Go to Automatic Level Control Suspension System Check

2

  1. Turn the ignition switch to the RUN position. Do not start the engine.
  2. Disconnect the load leveling timer relay.

Does the load leveling pump stop running?

--

Go to Step 3

Go to Step 8

3

Test CKT 1250 (BLK) at terminal F, of the load leveling timer relay for a short to ground.

Is a short to ground present in CKT 1250 (BLK)?

--

Go to Step 4

Go to Step 7

4

  1. Disconnect the load leveling air inflator switch.
  2. Test CKT 1250 (BLK) at terminal F of the load leveling timer relay for a short to ground.

Is a short to ground present in CKT 1250 (BLK)?

--

Go to Step 5

Go to Step 6

5

Repair the short to ground in CKT 1250 (BLK).

Is the repair complete?

--

Go to Automatic Level Control Suspension System Check

--

6

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

Is the replacement complete?

--

Go to Automatic Level Control Suspension System Check

--

7

Replace the load leveling timer relay. Refer to Automatic Level Control Relay Replacement .

Is the replacement complete?

--

Go to Automatic Level Control Suspension System Check

--

8

Disconnect the load leveling height sensor.

Does the load leveling pump stop running?

--

Go to Step 9

Go to Step 10

9

Replace the load leveling height sensor. Refer to Automatic Level Control Sensor and Bracket Replacement .

Is the replacement complete?

--

Go to Automatic Level Control Suspension System Check

--

10

  1. Turn the ignition switch to the OFF position.
  2. Disconnect the load leveling pump.
  3. Test CKT 321 (YEL) of the load leveling pump for a short to ground.

Is a short to ground present in CKT 321 (YEL)

--

Go to Step 11

Go to Step 12

11

Repair the short to ground in CKT 321 (YEL).

Is the repair complete?

--

Go to Automatic Level Control Suspension System Check

--

12

  1. Remove the relay in the load leveling pump.
  2. Reconnect the load leveling pump.

Does the load leveling pump run?

--

Go to Step 13

Go to Step 14

13

Repair the short to voltage on the BLK/LT GRN wire.

Is the repair complete?

--

Go to Automatic Level Control Suspension System Check

--

14

Replace the relay in the load leveling pump. Refer to Air Compressor Relay Replacement .

Is the replacement complete?

--

Go to Automatic Level Control Suspension System Check

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