For 1990-2009 cars

### Circuit Description

When the Automatic Level Control (ALC) sensor detects an out of trim condition, the rear suspension leveling air compressor relay K19 energizes to provide B+ to the rear suspension leveling air compressor. The automatic level control sensor continuously monitors the controlling circuitry to determine if there is B+ present for a compress sequence or an air replenishment cycle (ARC).

### Conditions for Setting the DTC

The sensor detects that the relay output is not pulled down to ground when the sensor output is active.

### Action Taken When the DTC Sets

• | The sensor flashes the LEVELING indicator lamp.

• | The sensor's discrete low side output drive for the relay is disabled.

• | The sensor continuously attempts to recover form the fault

• | DTC 05 is stored as a history code at the end of the ignition cycle

### Conditions for Clearing the DTC

• | When the sensor does not detect B+ at the low side drive output of the relay when a compress sequence or an ARC is required.

• | Using a scan tool.

### Diagnostic Aids

Refer to the diagnostic table.

### Test Description

The number(s) below refer to the step number(s) on the diagnostic table.

1. This step checks circuits B25 and B56.

2. This step replaces the ALC sensor.

#### DTC 05 Compressor Relay Short to Battery

Step | Action | Value(s) | Yes | No
--- | --- | --- | --- | ---
1 | Has the Automatic Level Control (ALC) system Check been performed | -- | Go to Step 2 | Go to ALC Suspension System Check .
2 |

1. Disconnect the rear suspension leveling air compressor relay K19 from the relay box.
2. Turn the ignition switch to the ON.
3. Use a DMM in order to measure the voltage between terminal C of the ALC sensor connector and a known good ground.

Is the voltage within the specified range?

B+

Go to Step 3

Go to Step 4

3 | Locate and repair a short to B+ in circuits B25 and/or B56. If the circuits are OK, replace the rear suspension leveling air compressor relay K19. Is the repair or replacement complete? | -- | Go to Step 5 | --
4 | Replace the ALC sensor. Refer to Automatic Level Control in Suspension. Is the replacement complete? | -- | Go to Step 5 | --
5 |

1. Clear any DTCs.
2. Connect all of the connectors that were disconnected.
3. Reinstall components that were removed.
4. Wait for at least 5 minutes.
5. Turn the ignition switch to the ON position.

Is the LEVELING indicator lamp flashing?

--

Go to Step 1

System OK