For 1990-2009 cars

### Circuit Description

The exhaust valve is controlled by the Automatic Level Control (ALC) sensor. The sensor provides a low side drive whenever exhaust activity is required and during a 'head-relief' sequence, which occurs before each compressor start up. This drive output from the sensor is continually monitored to determine if the voltage level agrees with the commanded state.

### Conditions for Setting the DTC

The sensor detects a feedback voltage less than the preset threshold during an exhaust valve OFF state.

### Action Taken When the DTC Sets

• | The sensor flashes the LEVELING indicator lamp.

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

• | The sensor contentiously attempts to recover from the fault.

• | DTC 06 is stored as a history code at the end of the ignition cycle.

### Conditions for Clearing the DTC

• | The DTC will clear when B+ is present at the low side output drive.

• | Using a scan tool.

### Diagnostic Aids

• | Perform the system leak test. Refer to Automatic Level Control System.

• | Refer to the diagnostic table.

### Test Description

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

1. Checks for an open or short to ground in circuit A200.

2. Checks for an open or short to ground in circuit M101.

3. Checks for an internal open or short to ground in the exhaust valve.

#### DTC 06 Exhaust Valve Short to Ground/Open Circuit

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

1. Disconnect the rear suspension leveling air compressor connector.
2. Use a DMM to measure the voltage between terminal C of the compressor connector and a known good ground.

Is the voltage within the specified value?

B+

Go to Step 4

Go to Step 3

3 | Locate and repair an open, high resistance or a short to ground in circuit A200. Is the repair complete? | -- | Go to Step 9 | --
4 |

1. Disconnect the ALC sensor connector.
2. Connect a fused jumper between terminal C and terminal A of the compressor connector.
3. Use a DMM to measure the voltage between terminal D of the sensor connector and a known good ground.

Is the voltage within the specified value?

B+

Go to Step 6

Go to Step 5

5 | Locate and repair an open, high resistance or a short to ground in circuit M101. Is the repair complete? | -- | Go to Step 9 | --
6 | Use the DMM to measure the resistance between terminal A and terminal C of the compressor. Is the resistance reading within the specified value? | 25 ohms-35 ohms | Go to Step 7 | Perform the system leak test. Refer to Automatic Level Control.
7 |

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

Is the LEVELING indicator lamp flash?

--

Go to Step 8

Go to Step 9

8 | Replace the ALC sensor. Refer to Automatic Level Control in Suspension. Is the replacement complete? | -- | Go to Step 9 | --
9 |

1. Connect all of the connectors that were disconnected.
2. Turn the ignition switch to the ON position.
3. Wait for at least 5 minutes.

Is the rear of the vehicle level?

--

System OK

Go to Step 1