SCHEMATIC REFERENCE: Automatic Level Control Schematics

Important: Perform a close visual inspection of all air lines, connectors and components.

Did you perform A Diagnostic System Check - Automatic Level Control?

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Go to Step 2

Go to Automatic Level Control Diagnostic System Check

1. Install a scan tool.
2. Turn ON the ignition, with the engine OFF.
3. With a scan tool, command the ALC relay ON and OFF.

Does the ALC relay turn ON and OFF with each command?

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Go to Step 8

Go to Step 3

1. Turn OFF the ignition.
2. Disconnect the ALC relay.
3. Turn ON the ignition, with the engine OFF.
4. Probe the coil side feed circuit of the ALC relay with a test lamp that is connected to a good ground.

Does the test lamp illuminate?

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Go to Step 4

Go to Step 15

1. Connect a test lamp between the control circuit of the ALC relay and the coil side feed circuit of the ALC relay.
2. With a scan tool, command the ALC relay ON and OFF .

Does the test lamp turn ON and OFF with each command?

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Go to Step 11

Go to Step 5

Does the test lamp remain illuminated with each command?

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Go to Step 7

Go to Step 6

Test the control circuit of the ALC relay for a short to voltage or an open. Refer to Circuit Testing Circuit Testing and Wiring Repairs in Wiring Systems.

Did you find and correct the condition?

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Go to Step 19

Go to Step 13

Test the control circuit of the ALC for a short to ground. Refer to Circuit Testing Circuit Testing and Wiring Repairs Wiring Repairs in Wiring Systems.

Did you find and correct the condition?

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Go to Step 19

Go to Step 13

1. Turn OFF the ignition.
2. Disconnect the ALC compressor motor.
3. Turn ON the ignition, with the engine OFF.
4. Probe the ALC compressor motor battery positive feed circuit with a test lamp connected to a good ground.
5. With a scan tool, command the ALC relay ON.

Did the test lamp illuminate?

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Go to Step 9

Go to Step 10

1. Turn OFF the ignition.
2. Disconnect the negative battery cable.
3. Measure the resistance of the ALC compressor ground circuit to a good ground.

Is the resistance lower than the specified value?

5 ohms

Go to Step 12

Go to Step 14

Test the ALC compressor motor battery positive feed circuit for an open. Refer to Circuit Testing in Wiring Systems.

Did you find and correct the condition?

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Go to Step 19

Go to Step 11

Inspect for poor connections at the ALC relay. Refer to Testing for Intermittent Conditions and Poor Connections and Connector Repairs in Wiring Systems.

Did you find and correct the condition?

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Go to Step 19

Go to Step 16

Inspect for poor connections at the ALC compressor assembly. Refer to Testing for Intermittent Conditions and Poor Connections and Connector Repairs in Wiring Systems.

Did you find and correct the condition?

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Go to Step 19

Go to Step 17

Inspect for poor connections at the harness connector of the Rear Integration Module (RIM). Refer to Testing for Intermittent Conditions and Poor Connections and Connector Repairs in Wiring Systems.

Did you find and correct the condition?

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Go to Step 19

Go to Step 18

Repair the high resistance/ open ALC compressor ground circuit. Refer to Wiring Repairs in Wiring Systems.

Did you complete the repair?

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Go to Step 19

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Repair the coil side feed circuit of the ALC relay Refer to Wiring Repairs in Wiring Systems.

Did you complete the repair?

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Go to Step 19

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Replace the ALC relay .

Did you complete the replacement?

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Go to Step 19

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

Did you complete the replacement?

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Go to Step 19

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Replace the RIM . Refer to Rear Integration Body Control Module Replacement in Body Controls.

Did you complete the replacement?

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Go to Step 19

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Operate the system to verify the repair.

Does the system operate normally?

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System OK

Go to Step 2