For 1990-2009 cars

Step | Action | Value(s) | Yes | No
--- | --- | --- | --- | ---
1 | Did you perform the ALC System Check? | -- | Go to Step 2 | Go to Automatic Level Control System Operation Check
2 | Does the compressor motor run for 3-5 seconds (air replenishment cycle) approximately every minute? | -- | Go to Step 17 | Go to Step 3
3 |

1. Turn the ignition OFF.
2. Disconnect the electrical connectors from the following components:

• | The ALC compressor motor

• | The INFLATOR relay (if applicable)

• | The trim height sensor

3. Connect a test light between B+ and the ALC height sensor terminal E, and then between B+ and the ALC height sensor terminal B.

Did the test light illuminate?

--

Go to Step 4

Go to Step 11

4 | Test for a short to ground in CKT 320. Did you find the condition? | -- | Go to Step 5 | Go to Step 6
5 | Repair the short to ground in CKT 320. Did you complete the repair? | -- | Go to Automatic Level Control System Operation Check | --
6 | Test for a short to ground in CKT 321. Did you find the condition? | -- | Go to Step 7 | Go to Step 8
7 | Repair a short to ground in CKT 321. Did you complete the repair? | -- | Go to Automatic Level Control System Operation Check | --
8 | Using a test light between B+ and the air inflator relay connector terminal A. Did the test light illuminate? | -- | Go to Step 9 | Go to Step 10
9 | Replace the air inflator relay. Refer to Automatic Level Control Relay Replacement . Did you complete the repair? | -- | Go to Automatic Level Control System Operation Check | --
10 | Replace the inflator air switch. Refer to Automatic Level Control Inflator Air Switch Replacement . Did you complete the repair? | -- | Go to Automatic Level Control System Operation Check | --
11 |

1. Connect the ALC height sensor electrical connector.
2. Disconnect the height sensor link from the rear axle tie rod.
3. Using a test light, backprobe between B+ and the ALC compressor connector terminal B.
4. Rotate the height sensor arm downward to 45 degrees below horizontal.
5. Turn the ignition switch to RUN then back to OFF.
6. Wait 7 - 27 seconds.

Did the test light illuminate?

--

Go to Step 13

Go to Step 12

12 | Replace the auto level control sensor. Refer to Automatic Level Control Sensor Link Replacement . Did you complete the repair? | -- | Go to Automatic Level Control System Operation Check | --
13 | Rotate the height sensor arm to 45° above horizontal. Did the test light illuminate? | -- | Go to Step 12 | Go to Step 14
14 |

1. Use a test light in order to backprobe between the ALC compressor connector terminals A and D.
2. Rotate the height sensor arm up 45° above horizontal.
3. Turn the ignition switch to RUN then back to OFF.
4. Wait 7 - 27 seconds.

Did the test light turn OFF?

--

Go to Step 15

Go to Step 12

15 | Rotate the height sensor arm to 45° below horizontal. Did the test light turn OFF? | -- | Go to Step 16 | Go to Step 12
16 |

1. Connect the ALC compressor electrical connector.
2. Use a test light and backprobe between the ALC compressor relay terminals 30 and 87.

Does the test lamp illuminate?

--

Go to Step 17

Go to Step 18

17 | Replace the auto level control air compressor relay. Did you complete the repair? | -- | Go to Automatic Level Control System Operation Check | --
18 | Replace the auto level control air compressor. Refer to Air Compressor Replacement . Did you complete the repair? | -- | Go to Automatic Level Control System Operation Check | --