Circuit Description
The Automatic Level Control (ALC) exhaust solenoid valve is controlled (switched ON or OFF) by the Continuously Variable Road Sensing Suspension (CVRSS) module. The control module provides a low-side drive (switched to ground) whenever exhaust activity is required and during a head-relief sequence which occurs before each compressor start-up. This drive output from the CVRSS module is continually monitored to determine if the voltage level agrees with the commanded state.
Conditions for Running the DTC
| • | The Ignition is on. |
| • | The fault is detected during three consecutive ignition cycles, or during the same ignition cycle after clearing the DTC with a scan tool. |
Conditions for Setting the DTC
The DTC will set when the Electronic Suspension Control (ELC) module measures a feedback voltage condition in the exhaust solenoid control circuit less than a preset threshold during an exhaust solenoid valve OFF-state.
Action Taken When the DTC Sets
| • | ALL rear leveling activity for the remainder of the ignition cycle will be disabled. |
| • | The SERVICE RIDE CONTROL message will be displayed. |
Conditions for Clearing the MIL/DTC
| • | The scan tool can be used to clear the DTC. |
| • | The On-Board diagnostic CLEAR RSS CODES feature can be used to clear the DTC. |
| • | The DTC is saved as history when the Electronic Suspension Control (ELC) module no longer sees a low voltage condition in the exhaust solenoid control circuit when the exhaust solenoid valve is in an OFF-state. The DTC will clear if the fault does not return after 50 consecutive ignition cycles. |
Diagnostic Aids
A temporary compressor overload (i.e., high head pressure during a cold start) may cause the ELC fuse to open. This is one possible cause of DTC C0662.
A DTC C0662 fault condition is detectable only when the exhaust solenoid valve output is commanded to the OFF-state, which occurs whenever exhaust activity is not required. The Electronic Suspension Control (ELC) module expects to see a high voltage condition during the OFF-state.
Only electrical problems with the exhaust solenoid valve are flagged. Pneumatic blockage problems do not set a DTC, but the Electronic Suspension Control (ELC) module shuts off the exhaust function if no progress is made, or if excessive run time occurs. Recovery is not attempted until the ignition is cycled OFF and ON.
Check for disconnected or damaged air lines. Replace or reconnect the air lines as needed.
Test Description
The number(s) below refer to the step number(s) on the diagnostic table.
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Listen for an audible click when the [XX solenoid/relay] operates. Command both the ON and OFF states. Repeat the commands as necessary.
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Tests for voltage at the coil side of the ALC exhaust solenoid. The ELC fuse supplies power to the coil side of the solenoid.
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Verifies that the Electronic Suspension Control (ELC) module is providing ground to the solenoid.
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Tests if ground is constantly being applied to the solenoid.
Step | Action | Value(s) | Yes | No |
|---|---|---|---|---|
1 | Did you perform the Road Sensing Suspension Diagnostic System Check? | -- | Go to Step 2 | Go to Diagnostic System Check |
Does the exhaust solenoid turn ON and OFF with each command? | -- | Go to Diagnostic Aids | Go to Step 3 | |
Does the test lamp illuminate? | -- | Go to Step 4 | Go to Step 10 | |
Does the test lamp turn ON and OFF with each command? | -- | Go to Step 8 | Go to Step 5 | |
Does the test lamp remain illuminated with each command? | -- | Go to Step 7 | Go to Step 6 | |
6 | Test the control circuit of the exhaust solenoid for an open. Refer to Circuit Testing and Wiring Repairs in Wiring Systems. Did you find and correct the condition? | -- | Go to Step 13 | Go to Step 9 |
7 | Test the control circuit of the exhaust solenoid for a short to ground. Refer to Circuit Testing and Wiring Repairs in Wiring Systems. Did you find and correct the condition? | -- | Go to Step 13 | Go to Step 9 |
8 | Inspect for poor connections at the exhaust solenoid. Refer to Testing for Intermittent Conditions and Poor Connections and Connector Repairs in Wiring Systems. Did you find and correct the condition? | -- | Go to Step 13 | Go to Step 11 |
9 | Inspect for poor connections at the the Electronic Suspension Control (ELC) module. Refer to Testing for Intermittent Conditions and Poor Connections and Connector Repairs in Wiring Systems. Did you find and correct the condition? | -- | Go to Step 13 | Go to Step 12 |
10 | Repair the coil side feed circuit of the exhaust solenoid. Refer to Wiring Repairs in Wiring Systems. Did you complete the repair? | -- | Go to Step 13 | -- |
11 | Replace the exhaust solenoid. Did you complete the replacement? | -- | Go to Step 13 | -- |
12 |
Important: Perform the set up procedure for the Electronic Suspension Control (ELC) module . Replace the Electronic Suspension Control (ELC) module. Refer to Electronic Suspension Control Module Replacement . Did you complete the replacement? | -- | Go to Step 13 | -- |
13 |
Does the DTC reset? | -- | Go to Step 2 | System OK |
