Circuit Description
The automatic level control (ALC) sensor activates the LEVELING indicator lamp whenever a compress cycle is requested. The sensor provides a switched path to ground. The sensor will flash the lamp when certain DTCs are detected.
Conditions for Setting the DTC
The DTC sets when the sensor detects that the lamp output is not pulled down ground when the sensor output is active and the ignition signal is high.
Action Taken When the DTC Sets
| • | The sensor's discrete low side output drive for the lamp is disabled. |
| • | The sensor continuously attempts to recover from the fault. |
Conditions for Clearing the DTC
| • | A current DTC becomes a history DTC when conditions for the fault are no longer present and the ignition cycles from OFF to ON. |
| • | A history DTC will clear after 20 ignition cycles. |
| • | Use a scan tool in order to clear this DTC. |
Diagnostic Aids
Inspect for the following conditions if a history or intermittent DTC is indicated:
| • | A damaged wiring harness |
| Inspect the wiring harness for damage. If the wiring harness appears to be in good condition, observe the display on the DMM while moving the connectors and wiring harnesses related to the circuits. A change in the DMM display during this test will indicate the location of the fault. |
| • | For additional information, refer to Intermittents and Poor Connections Diagnosis in Wiring Systems. |
Test Description
The number(s) below refer to the step number(s) on the diagnostic table.
Step | Action | Value(s) | Yes | No |
|---|---|---|---|---|
1 | Was the Automatic Level Control (ALC) System Check performed? | -- | Go to Step 2 | |
Is the voltage reading equal to the specified value? | B+ | Go to Step 3 | Go to Step 4 | |
3 | Locate and repair a short to B+ in circuit XY1 and/or circuit XY2. Is the repair complete? | -- | Go to Step 5 | -- |
4 | Replace the ALC sensor. Refer to Automatic Level Control Sensor Replacement . Is the replacement complete? | -- | Go to Step 5 | -- |
5 |
Does the LEVELING indicator lamp operate properly? | -- | System OK | Go to Step 1 |
