Step | Action | Value(s) | Yes | No |
|---|---|---|---|---|
1 | Is any aftermarket equipment installed on the vehicle that could affect the ALC system? | -- | Go to Step 2 | Go to Step 4 |
2 | Check the aftermarket equipment to ensure that it is not affecting ALC performance. Is the aftermarket equipment affecting the ALC performance? | -- | Go to Step 3 | Go to Step 4 |
3 | Correct the condition. Is the condition corrected? | -- | -- | |
4 | Check the ELC fuse or the ELC circuit breaker for an open. Is the fuse or circuit breaker open? | -- | Go to Step 5 | Go to Step 6 |
5 |
Important: If the fuse or circuit breaker is open repeatedly, check CKT 340 for a short to ground. Replace the fuse or reset the circuit breaker. Is the replacement or reset complete? | -- | -- | |
6 | Check the height sensor and link for proper connection and damage. Are the height sensor and link properly connected and in good condition? | -- | Go to Step 8 | Go to Step 7 |
7 | Reconnect or replace the height sensor or link. Refer to Automatic Level Control Sensor and Bracket Replacement . Is the repair or replacement complete? | -- | -- | |
8 |
Important: The vehicle must be raised on a drive-on lift or be supported at the rear under the rear axle. Full vehicle weight must be on the rear suspension. Important: The height sensor has a 17-27 second delay period before the exhaust solenoid is activated. Will the rear of the vehicle lower to trim level or below? | -- | Go to Step 9 | Go to Step 10 |
9 | Adjust the height sensor. Refer to Automatic Level Control Sensor Adjustment . Is the adjustment complete? | -- | -- | |
10 | Move the height sensor lever up so that it is approximately 45 degrees above level (to the floor) and hold it there for a minimum of 27 seconds (17-27 seconds is the height sensor delay period). Does the air compressor come on? | -- | Go to Step 11 | |
11 | Disconnect the air tube from the air dryer. Will the rear of the vehicle lower to trim level or below? | -- | Go to Step 19 | Go to Step 12 |
12 |
Will the rear of the vehicle lower to trim level or below? | -- | Go to Step 13 | Go to Step 14 |
13 | Replace the air tube. Refer to Air Tube Replacement . Is the replacement complete? | -- | -- | |
14 | Is the vehicle uneven (more than 19 mm (0.75 in) from side to side at the rear? | -- | Go to Step 16 | Go to Step 15 |
15 | Replace both rear springs. Refer to Coil Spring Insulators Replacement . Is the trim height at the rear underbody points correct? Refer to Trim Height . | -- | -- | |
16 |
Is the vehicle still uneven more than 19 mm (0.75 in) from side to side at the rear? | -- | Go to Step 17 | Go to Step 18 |
17 | Replace the rear spring on the side of the vehicle that is high. Refer to Coil Spring Insulators Replacement . Is the trim height at the rear underbody points correct? Refer to Trim Height . | -- | Go to Step 1 | |
18 | Replace the rear shock absorber on the side of the vehicle that is high. Refer to Shock Absorber Replacement . Is the trim height at the rear underbody points correct? Refer to Trim Height . | -- | Go to Step 1 | |
19 |
Important: The height sensor has a 17-27 second delay period before the air compressor is activated. Is continuity present? | Continuity | Go to Step 21 | Go to Step 20 |
20 | Replace the air compressor head. Refer to Automatic Level Control Air Compressor Head Replacement . Is the replacement complete? | -- | -- | |
21 | Measure the voltage between the air compressor electrical connector (vehicle side), terminal A and ground. Is the measurement within the specified values? | 10.5-15 V | Go to Step 23 | Go to Step 22 |
22 | Check for a poor connection at the rear junction block. If the connections are OK, repair the open in CKT 340. Is the repair complete? | -- | -- | |
23 |
Important: The link must be connected. Voltage will not be present within 17-27 seconds of the ignition switch cycle (height sensor delay). Voltage will not be present after approximately seven minutes. Is the measurement within the specified values? | 10.5-15 V | Go to Step 25 | Go to Step 24 |
24 | Check for an open in CKT 320. Also, check for a poor connection at the rear junction block and at the height sensor connector. Was an open or poor connection found and repaired? | -- | ||
25 | Replace the air compressor head. Refer to Automatic Level Control Air Compressor Head Replacement . Is the replacement complete? | -- | -- |
