Step | Action | Value(s) | Yes | No |
|---|---|---|---|---|
DEFINITION: | ||||
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 (G Car) or the ELC circuit breaker (C Car for an open (blown) condition. Is the fuse or circuit breaker open? | -- | Go to Step 5 | Go to Step 6 |
5 | Replace the fuse or reset the circuit breaker. NOTE: If the fuse or circuit breaker is open (blown) repeatedly, check CKT 340 (ORN) for a short circuit to ground condition. 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. Will the rear of the vehicle lower to trim level or below? NOTE: The height sensor has a 17 to 27 second delay period before the exhaust solenoid is activated. | -- | Go to Step 9 | Go to Step 10 |
9 | Adjust the height sensor. Refer to Automatic Level Control Sensor Adjustment . Is trim height at the rear underbody points correct? Refer to Trim Height . | Trim Height | Repeat this Step | |
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 to 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 . | Trim Height | -- | |
16 |
Is the vehicle still uneven more than 19 mm (.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 . | Trim Height | Repeat this Diagnostic Table | |
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 . | Trim Height | Repeat this Diagnostic Table | |
19 |
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 battery voltage present? | Battery Voltage | 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 circuit condition in circuit 340. Is the repair complete? | -- | -- | |
23 |
Is battery voltage present? | Battery Voltage | Go to Step 25 | Go to Step 24 |
24 | Check for an open circuit condition in circuit 320. Also, check for a poor connection at the rear junction block and at the height sensor connector. Was an open circuit 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? | -- | -- | |
