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
This DTC sets when the sensor detects that the lamp output is not externally pulled up to B+ when the sensor output is not 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 poor connection at the ALC sensor |
| Inspect the harness connectors for backed out terminals, improper mating, improperly formed or damaged terminals, and poor terminal to wire connections. |
| • | 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. |
| • | Verify the integrity of the LEVELING indicator lamp bulb. |
Test Description
The number(s) below refer to the step number(s) on the diagnostic table.
-
This step checks for a short to ground in circuit XY1 or circuit XY2.
-
This step checks for an open in circuit XY1 or circuit XY2.
Step | Action | Value(s) | Yes | No |
|---|---|---|---|---|
1 | Was the Automatic Level Control (ALC) System Check performed? | -- | Go to Step 2 | |
Is the LEVELING indicator lamp illuminated? | -- | Go to Step 3 | Go to Step 4 | |
3 | Locate and repair a short to ground in circuit XY1 and/or circuit XY2. Is the repair complete? | -- | Go to Step 7 | -- |
Connect a 3A fused jumper wire between terminal G of the sensor connector and a known good ground. Is the LEVELING indicator lamp illuminated? | -- | Go to Step 6 | Go to Step 5 | |
5 | Locate and repair an open in circuit XY1 and/or circuit XY2. Is the repair complete? | -- | Go to Step 7 | -- |
6 | Replace the ALC sensor. Refer to Automatic Level Control Sensor Replacement . Is the replacement complete? | -- | Go to Step 7 | -- |
7 |
Does the LEVELING indicator lamp operate properly? | -- | System OK | Go to Step 1 |
