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Home >> Isuzu >> 2007 >> i-290 LS, Standard >> Repair and Diagnosis >> External Pages >> Different car >> Section 50 (Suspension Control System - Suspension Leveling (ESCM)) >> Diagnostic Information and Procedures >> Rear of Vehicle Low

Rear of Vehicle Low

WARNING: This page is about a different car, the 2007 Cadillac DTS. However, it is still accessible from the selected car via links, so may be relevant.
Rear of Vehicle Low

Step Action Yes No
Schematic Reference: Automatic Level Control Schematics 
1 Did you perform the Diagnostic System Check - Vehicle? Go to Step 2  Go to Diagnostic System Check - Vehicle
2
  1. Turn ON the ignition, with the engine OFF.
  2. Listen for the automatic level control (ALC) air compressor to activate.
Does the air compressor come on within 30 seconds?		 Go to Step 9  Go to Step 3 
3
  1. Turn OFF the ignition.
  2. Disconnect the ALC connector from the ALC air compressor assembly.
  3. Disconnect the electronic suspension control (ESC) module connector.
  4. Turn ON the ignition, with the engine OFF.
  5. Jumper the ALC relay control circuit to ground.
  6. Measure the voltage between the ALC compressor motor control circuit of the ALC air compressor connector and ground.
Does the voltmeter display a voltage greater than 10 volts?		 Go to Step 4  Go to Step 7 
4
  1. Remove the jumper wire from the ALC relay control circuit.
  2. Turn OFF the ignition.
  3. Check for continuity between ALC compressor ground circuit of the ALC air compressor connector and ground.
Is there continuity?		 Go to Step 6  Go to Step 5 
5
  1. Turn OFF the ignition.
  2. Repair the open circuit in the ALC air compressor ground circuit.
Is the repair complete?		 Go to Step 14  -
6 Replace the ALC air compressor assembly. Refer to Air Compressor Replacement .
Is the repair complete?		 Go to Step 12  -
7
  1. Remove the jumper wire from ALC relay control circuit.
  2. Turn OFF the ignition.
  3. Inspect for the following:
    • Open ELC fuse
    • Inoperable electronic level control (ELC) relay
    • Open ALC air compressor control circuit
    • Open ELC relay control circuit
Did you find and correct the condition?		 Go to Step 8  -
8
IMPORTANT: A blown fuse may indicate:
  • No compressor head pressure relief
  • A faulty air compressor
  • A short to ground in the exhaust solenoid supply circuit
Repair the shorted circuit condition or replace the fuse.Is the repair complete?		 Go to Step 14  -
9 Inspect the left and right rear position sensors for damage and disconnected links.
Are any damaged sensors or disconnected links present?		 Go to Step 13  Go to Step 10 
10 Perform the ALC System Leak Test.
Is a leak present?		 Go to Step 11  Go to Step 12 
11 Repair the leak in the ALC System.
Is the repair complete?		 Go to Step 14  -
12
  1. Turn OFF the ignition.
  2. Connect the scan tool.
  3. Turn ON the ignition, with engine OFF.
  4. Perform the ALC trim height adjustment.
Has the ALC trim height adjustment been completed?		 Go to Step 14  -
13 Replace the damaged rear position sensor or reconnect the link. Refer to Automatic Level Control Sensor Replacement .
Is the replacement complete?		 Go to Step 14  -
14 Operate the system in order to verify the repair.
Did you correct the condition?		 System OK Go to Step 1 
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