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Suspension Control System - Suspension Leveling Chevrolet Avalanche II

Electronic Suspension 2 illustrations ~4990 words

Fastener Tightening Specifications

ApplicationSpecification
MetricEnglish
Air Compressor to Frame Nuts15 N.m11 lb ft
Air Line Tube Repair Nut8 N.m70 lb in

Scheme 7

Scheme 7: Automatic Level Control Schematics
Scheme 7: Automatic Level Control Schematics

Scheme 8

Scheme 8
Scheme 8

DIAGNOSTIC CODE INDEX

DTCDescription
DTC C0660C0660 01: Level Control Exhaust Circuit Short to Battery C0660 06: Level Control Exhaust Circuit Short to Ground or Open Circuit
DTC C0711C0711 00: Level Control Air Pressure Sensor Malfunction Signal Invalid
DTC C0712C0712 01: Level Control Compressor Relay Circuit Short to Battery C0712 06: Level Control Compressor Relay Circuit Short to Ground or Open Circuit

DIAGNOSTIC CODE INDEX

Diagnostic Starting Point - Automatic Level Control

Begin the system diagnosis with Diagnostic System Check - Vehicle (with HP2) or Diagnostic System Check - Vehicle (without HP2) . The Diagnostic System Check will provide the following information

  1. The identification of the control module which command the system
  2. The ability of the control module to communicate through the serial data circuit
  3. The identification of any stored DTCs and their status

The use of the Diagnostic System Check will identify the correct procedure for diagnosing the system and where the procedure is located.

Diagnostic Instructions

  1. Perform the «Diagnostic System Check - Vehicle (with HP2)»(/chevrolet/avalanche/ii-2006-2013/remont/oem-general-information/#vehicle-diagnostic-information-2-of-2__diagnostic-system-check-vehicle-with) or «Diagnostic System Check - Vehicle (without HP2)»(/chevrolet/avalanche/ii-2006-2013/remont/oem-general-information/#vehicle-diagnostic-information-2-of-2__diagnostic-system-check-vehicle-without) prior to using this diagnostic procedure.
  2. Review «Strategy Based Diagnosis»(/chevrolet/avalanche/ii-2006-2013/remont/oem-general-information/#vehicle-diagnostic-information-2-of-2__strategy-based-diagnosis) for an overview of the diagnostic approach.
  3. «Diagnostic Procedure Instructions»(/chevrolet/avalanche/ii-2006-2013/remont/oem-general-information/#vehicle-diagnostic-information-2-of-2__diagnostic-procedure-instructions) provides an overview of each diagnostic category.

Diagnostic Fault Information

CircuitShort to GroundOpen/High ResistanceShort to VoltageSignal Performance
Automatic Level Control Exhaust Solenoid Control CircuitC0660 06C0660 06C0660 01
Automatic Level Control Exhaust Solenoid Supply Voltage CircuitC0660 06C0660 06

Circuit Description

The electronic suspension control module (ESCM) adjusts the vehicle suspension ride height. The ESCM determines the height of the vehicle based on signals from the height sensors. The ESCM raises and lowers the vehicle in order to keep the vehicle level by controlling the exhaust valve and air compressor control circuits.

Conditions for Running the DTC

  1. Battery voltage is between 9-16 volts.
  2. The exhaust valve is commanded ON.

Conditions for Setting the DTC

  1. The exhaust solenoid control circuit is shorted to voltage, ground, or open when solenoid activation is commanded ON for 2.5 seconds.
  2. The exhaust solenoid supply voltage circuit is shorted to ground or open when solenoid activation is commanded ON for 5 seconds.

Action Taken When the DTC Sets

  1. The electronic suspension control system will be inoperative.
  2. The SERVICE SUSPENSION SYSTEM message will be displayed.

Conditions for Clearing the MIL/DTC

  1. DTC C0660 will change from a current DTC to a history DTC on the next ignition cycle.
  2. DTC C0660 will be cleared from history after 50 ignition cycles.

Reference Information

Schematic Reference

Connector End View Reference

Description and Operation

Electrical Information Reference

  1. «Circuit Testing»(/chevrolet/avalanche/ii-2006-2013/remont/ignition-switchsteering-lock/#wiring-systems-and-power-management-service-troubleshooting-diagnosis__circuit-testing)
  2. «Connector Repairs»(/chevrolet/avalanche/ii-2006-2013/remont/ignition-switchsteering-lock/#wiring-systems-and-power-management-service-troubleshooting-diagnosis__connector-repairs)
  3. «Testing for Intermittent Conditions and Poor Connections»(/chevrolet/avalanche/ii-2006-2013/remont/ignition-switchsteering-lock/#wiring-systems-and-power-management-service-troubleshooting-diagnosis__testing-for-intermittent-conditions-and-poor)
  4. «Wiring Repairs»(/chevrolet/avalanche/ii-2006-2013/remont/ignition-switchsteering-lock/#wiring-systems-and-power-management-service-troubleshooting-diagnosis__wiring-repairs)

Scan Tool Reference

Control Module References for scan tool information

Circuit/System Verification

Ignition ON, command the Exhaust Valve ON and OFF with the scan tool output control. The exhaust solenoid valve should turn ON and OFF with each command.

Circuit/System Testing

  1. Ignition OFF, disconnect the automatic level control (ALC) compressor exhaust solenoid.
  2. Ignition ON, verify that a test lamp does not illuminate between the solenoid control circuit terminal C at the connector and ground. If the test lamp illuminates, test the control circuit for a short to voltage.
  3. Verify that a test lamp illuminates between the B+ circuit terminal B and ground. If the test lamp does not illuminate, test the B+ circuits for a short to ground or an open/high resistance. If the circuit tests normal, test or replace the ALC compressor.
  4. Connect a test lamp between the B+ circuit terminal B and the control circuit terminal C.
  5. With a scan tool, clear all ALC DTCs.
  6. Command the exhaust solenoid ON and OFF. The test lamp should turn ON and OFF when changing between the commanded states. If the test lamp is always ON, test the control circuit for a short to ground. If the circuit tests normal, replace the ESCM. If the test lamp is always OFF, test the control circuit for a short to voltage or an open/high resistance. If the circuit tests normal, replace the ESCM.
  7. If all circuits test normal, test or replace the ALC compressor.

Repair Procedures

Perform the Diagnostic Repair Verification after completing the diagnostic procedure.

  1. «Air Compressor Replacement»(/chevrolet/avalanche/ii-2006-2013/remont/electronic-suspension/#suspension-control-system-suspension-leveling)
  2. «Suspension Position Calibration (Without Z95)»(/chevrolet/avalanche/ii-2006-2013/remont/electronic-suspension/#suspension-control-system-suspension-leveling) or «Suspension Position Calibration (With Z95)»(/chevrolet/avalanche/ii-2006-2013/remont/electronic-suspension/#suspension-control-system-suspension-leveling)
  3. «Control Module References»(/chevrolet/avalanche/ii-2006-2013/remont/communication-devices/#programming-and-setup-all-systems__control-module-references) for ESCM replacement, setup, and programming
  1. Perform the «Diagnostic System Check - Vehicle (with HP2)»(/chevrolet/avalanche/ii-2006-2013/remont/oem-general-information/#vehicle-diagnostic-information-2-of-2__diagnostic-system-check-vehicle-with) or «Diagnostic System Check - Vehicle (without HP2)»(/chevrolet/avalanche/ii-2006-2013/remont/oem-general-information/#vehicle-diagnostic-information-2-of-2__diagnostic-system-check-vehicle-without) prior to using this diagnostic procedure.
  2. Review «Strategy Based Diagnosis»(/chevrolet/avalanche/ii-2006-2013/remont/oem-general-information/#vehicle-diagnostic-information-2-of-2__strategy-based-diagnosis) for an overview of the diagnostic approach.
  3. «Diagnostic Procedure Instructions»(/chevrolet/avalanche/ii-2006-2013/remont/oem-general-information/#vehicle-diagnostic-information-2-of-2__diagnostic-procedure-instructions) provides an overview of each diagnostic category.
CircuitShort to GroundOpen/High ResistanceShort to VoltageSignal Performance
Air Suspension Pressure Sensor Low Reference CircuitC0711
Air Suspension Pressure Sensor 5 Volt Voltage Reference CircuitC0711C0711C0711
Air Suspension Pressure Sensor Signal CircuitC0711C0711C0711C0711

The automatic level control (ALC) pressure sensor sends a voltage signal to the electronic suspension control module (ESCM) that corresponds to a pressure within the range of 30-180 psi.

Battery voltage is between 9-16 volts.

The ESCM detects that the supplied 5 volt reference voltage circuit for the pressure sensor falls below 4.75 volts or exceeds 5.25 volts.

The ESCM detects that the signal voltage circuit for the pressure sensor falls below .5 volt or exceeds 4.75 volts.

  1. The air suspension system will be inoperative.
  2. The SERVICE SUSPENSION SYSTEM message will be displayed.
  1. When the fault is no longer present, DTC C0711 will change from a current DTC to a history DTC on the next ignition cycle.
  2. DTC C0711 will be cleared from history after 50 ignition cycles.

Schematic Reference

Connector End View Reference

Description and Operation

Electrical Information Reference

  1. «Circuit Testing»(/chevrolet/avalanche/ii-2006-2013/remont/ignition-switchsteering-lock/#wiring-systems-and-power-management-service-troubleshooting-diagnosis__circuit-testing)
  2. «Connector Repairs»(/chevrolet/avalanche/ii-2006-2013/remont/ignition-switchsteering-lock/#wiring-systems-and-power-management-service-troubleshooting-diagnosis__connector-repairs)
  3. «Testing for Intermittent Conditions and Poor Connections»(/chevrolet/avalanche/ii-2006-2013/remont/ignition-switchsteering-lock/#wiring-systems-and-power-management-service-troubleshooting-diagnosis__testing-for-intermittent-conditions-and-poor)
  4. «Wiring Repairs»(/chevrolet/avalanche/ii-2006-2013/remont/ignition-switchsteering-lock/#wiring-systems-and-power-management-service-troubleshooting-diagnosis__wiring-repairs)

Scan Tool Reference

Control Module References for Scan Tool Information

  1. Verify that there are no air leaks in the system. If a leak is found, repair or replace the leaking component as necessary.
  2. Ignition OFF, remove the ESC/ALC EXH Fuse in the underhood fuse block.
  3. Disconnect the air pressure sensor and test for less than 2.0 ohms of resistance between the low reference terminal F at the harness connector and ground. If greater than specified, test the low reference circuit for open/high resistance. If the circuit tests normal, replace the electronic suspension control module.
  4. Ignition ON, verify that 4.75-5.25 volts exists between the 5 volt reference circuit terminal A of the harness connector and ground. If less that the specified range, test the 5 volt reference circuit for open/high resistance or a short to ground. If the circuit tests normal, replace the electronic suspension control module. If greater that the specified range, test the 5 volt reference circuit for a short to voltage. If the circuit tests normal, replace the electronic suspension control module.
  5. Ignition OFF, disconnect the electronic suspension control module connector.
  6. Test the pressure sensor signal circuit for a short to ground, open/high resistance, or short to voltage. If all circuits test normal, test or replace the automatic level control compressor assembly.

Perform the Diagnostic Repair Verification after completing the diagnostic procedure.

  1. «Air Tube Repair»(/chevrolet/avalanche/ii-2006-2013/remont/electronic-suspension/#suspension-control-system-suspension-leveling__air-tube-repair)
  2. «Air Compressor Replacement»(/chevrolet/avalanche/ii-2006-2013/remont/electronic-suspension/#suspension-control-system-suspension-leveling)
  3. «Control Module References»(/chevrolet/avalanche/ii-2006-2013/remont/communication-devices/#programming-and-setup-all-systems__control-module-references) for Air Suspension Control Module replacement, setup and programming
  1. Perform the «Diagnostic System Check - Vehicle (with HP2)»(/chevrolet/avalanche/ii-2006-2013/remont/oem-general-information/#vehicle-diagnostic-information-2-of-2__diagnostic-system-check-vehicle-with) or «Diagnostic System Check - Vehicle (without HP2)»(/chevrolet/avalanche/ii-2006-2013/remont/oem-general-information/#vehicle-diagnostic-information-2-of-2__diagnostic-system-check-vehicle-without) prior to using this diagnostic procedure.
  2. Review «Strategy Based Diagnosis»(/chevrolet/avalanche/ii-2006-2013/remont/oem-general-information/#vehicle-diagnostic-information-2-of-2__strategy-based-diagnosis) for an overview of the diagnostic approach.
  3. «Diagnostic Procedure Instructions»(/chevrolet/avalanche/ii-2006-2013/remont/oem-general-information/#vehicle-diagnostic-information-2-of-2__diagnostic-procedure-instructions) provides an overview of each diagnostic category.
CircuitShort to GroundOpen/High ResistanceShort to VoltageSignal Performance
Automatic Level Control Relay Coil Control CircuitC0712 06C0712 06C0712 01
Automatic Level Control Relay Coil Supply Voltage CircuitC0712 06C0712 06

Circuit/System Description

The electronic suspension control module (ESCM) adjusts the vehicle suspension ride height. The ESCM determines the height of the vehicle based on the voltage from the suspension position sensors. The module grounds the ELC relay and the exhaust control solenoid to raise and lower the vehicle in order to keep the vehicle level.

  1. The ESCM is powered up.
  2. The ESCM is commanding the compressor ON.
  1. The compressor relay coil control circuit is shorted to voltage, ground, or open for 5 seconds.
  2. The compressor relay coil supply voltage circuit is shorted to ground, or open for 5 seconds.

The automatic level control (ALC) system will be inoperative.

Conditions for Clearing the DTC

The ESCM does not detect a failure during the self test.

Diagnostic Aids

This circuit is monitored during every functional operation of the compressor relay output and every 3.3 milliseconds when output is active. If a compressor relay fault is detected, the ESCM retries the output every 15 seconds to try to recover from the fault.

Schematic Reference

Connector End View Reference

Description and Operation

Electrical Information Reference

  1. «Circuit Testing»(/chevrolet/avalanche/ii-2006-2013/remont/ignition-switchsteering-lock/#wiring-systems-and-power-management-service-troubleshooting-diagnosis__circuit-testing)
  2. «Connector Repairs»(/chevrolet/avalanche/ii-2006-2013/remont/ignition-switchsteering-lock/#wiring-systems-and-power-management-service-troubleshooting-diagnosis__connector-repairs)
  3. «Testing for Intermittent Conditions and Poor Connections»(/chevrolet/avalanche/ii-2006-2013/remont/ignition-switchsteering-lock/#wiring-systems-and-power-management-service-troubleshooting-diagnosis__testing-for-intermittent-conditions-and-poor)
  4. «Wiring Repairs»(/chevrolet/avalanche/ii-2006-2013/remont/ignition-switchsteering-lock/#wiring-systems-and-power-management-service-troubleshooting-diagnosis__wiring-repairs)

Scan Tool Reference

Control Module References for Scan Tool Information

Ignition ON, command the compressor relay ON with a scan tool. Listen for the operation of the ALC relay and the automatic level control compressor.

  1. Ignition OFF, disconnect the ALC relay.
  2. Ignition ON, verify that a test lamp does not illuminate between the relay connector control circuit terminal 86 and ground. If the test lamp illuminates, test the control circuit for a short to voltage.
  3. Verify that a test lamp illuminates between the relay connector B+ circuit terminal 85 and ground. If the test lamp does not illuminate, test the B+ circuit for a short to ground or an open/high resistance. If the circuit tests normal and the B+ circuit fuse is open, test the relay coil B+ circuit for a short to ground. If all circuits test normal, test or replace the ELC relay.
  4. Verify that a test lamp illuminates between the relay connector B+ circuit terminal 30 and ground. If the test lamp does not illuminate, test the B+ circuit for an open/high resistance. If the circuit tests normal and the B+ circuit fuse is open, test the relay coil B+ circuit and compressor control circuit for a short to ground or a faulty ALC compressor motor. If all circuits test normal, test or replace the ELC relay.
  5. Disconnect the harness connector at the air compressor.
  6. Test for less than 1 ohm of resistance between the ALC compressor ground circuit terminal G and ground. If greater than 1 ohm, test the ground circuit for an open/high resistance.
  7. Connect the harness connector at the ALC compressor.
  8. Connect a 40-A fused jumper wire between the relay connector B+ circuit terminal 30 and the relay connector control circuit terminal 87. Verify the ALC compressor is activated. If the ALC compressor does not activate, test the control circuit for an open/high resistance. If the circuit tests normal, test or replace the ALC compressor.
  9. Connect a test lamp between the relay connecor B+ circuit terminal 85 and the relay connector control circuit terminal 86.
  10. Command the ALC compressor relay ON and OFF with a scan tool. The test lamp should turn ON and OFF when changing between the commanded states. If the test lamp is always ON, test the control circuit for a short to ground. If the circuit tests normal, replace the electronic suspension control module. If the test lamp is always OFF, test the control circuit for a short to voltage or an open/high resistance. If the circuit tests normal, replace the electronic suspension control module.
  11. If all circuits test normal, test or replace the ELC relay.

Component Testing

Relay Test

  1. Ignition OFF, disconnect the relay.
  2. Test for 50-200 ohms of resistance between terminals 85 and 86. If the resistance is not within the specified range, replace the relay.
  3. Test for infinite resistance between the following terminals: 30 and 86 30 and 87 30 and 85 85 and 87 If not the specified value, replace the relay.
  4. Install a 20 amp fused jumper wire between relay terminal 85 and 12 volts. Install a jumper wire between relay terminal 86 and ground. Test for less than 2.0 ohms of resistance between terminals 30 and 87. If greater than the specified range, replace the relay.

Perform the Diagnostic Repair Verification after completing the diagnostic procedure.

  1. «Relay Replacement (Attached to Wire Harness)»(/chevrolet/avalanche/ii-2006-2013/remont/ignition-switchsteering-lock/#wiring-systems-and-power-management-introduction) or «Relay Replacement (Within an Electrical Center)»(/chevrolet/avalanche/ii-2006-2013/remont/ignition-switchsteering-lock/#wiring-systems-and-power-management-introduction)
  2. «Air Compressor Replacement»(/chevrolet/avalanche/ii-2006-2013/remont/electronic-suspension/#suspension-control-system-suspension-leveling)
  3. «Suspension Position Calibration (Without Z95)»(/chevrolet/avalanche/ii-2006-2013/remont/electronic-suspension/#suspension-control-system-suspension-leveling) or «Suspension Position Calibration (With Z95)»(/chevrolet/avalanche/ii-2006-2013/remont/electronic-suspension/#suspension-control-system-suspension-leveling)
  4. «Control Module References»(/chevrolet/avalanche/ii-2006-2013/remont/communication-devices/#programming-and-setup-all-systems__control-module-references) for ESC module replacement, programming, and setup.

Symptoms - Automatic Level Control

Review the system operation in order to familiarize yourself with the system functions. Refer to Automatic Level Control Description and Operation .

Visual/Physical Inspection

  1. Inspect for aftermarket devices which could affect the operation of the automatic level control suspension. Refer to «Checking Aftermarket Accessories»(/chevrolet/avalanche/ii-2006-2013/remont/ignition-switchsteering-lock/#wiring-systems-and-power-management-service-troubleshooting-diagnosis__checking-aftermarket-accessories) .
  2. Inspect the easily accessible or visible system components for obvious damage or conditions which could cause the symptom.
  3. Inspect for binding or damaged shock absorbers.

Intermittent

Electrical connections or wiring may be the cause of intermittent conditions. Refer to Testing for Intermittent Conditions and Poor Connections .

Symptom List

Refer to a symptom diagnostic procedure from the following list in order to diagnose the symptom

  1. «Air Compressor Leak Test»(/chevrolet/avalanche/ii-2006-2013/remont/electronic-suspension/#suspension-control-system-suspension-leveling__air-compressor-leak-test)
  2. «Automatic Level Control System Leak Test»(/chevrolet/avalanche/ii-2006-2013/remont/electronic-suspension/#suspension-control-system-suspension-leveling)
  3. «Rear of Vehicle High»(/chevrolet/avalanche/ii-2006-2013/remont/electronic-suspension/#suspension-control-system-suspension-leveling)
  4. «Rear of Vehicle Low»(/chevrolet/avalanche/ii-2006-2013/remont/electronic-suspension/#suspension-control-system-suspension-leveling)

Air Compressor Leak Test

Special Tools

  1. J 22124-B Pressure Gage (0-300 psi)
  2. J 22124-91 Pressure Gage Adapter
  1. Attach the J 22124-91 to the air dryer.
  2. Attach the J 22124-B to the J 22124-91 with the toggle valve on the opposite side of the air compressor. Close the toggle valve.
  3. Apply air pressure at the schrader valve. Pressurize until the J 22124-B reads 690 kPa (100 psi).
  4. Check the following areas using soap bubbles: Solenoid valve Air dryer to compressor head O-ring Air dryer cover Air compressor head gasket Air compressor head cover-If necessary, tighten the cover bolts to 5.6 N.m (50 lb in).

If a leak is found, replace the air compressor. Refer to Air Compressor Replacement .

Tools Required

J 22124-B Pressure Gage (0-300 psi)

  1. Disconnect the air tube from the air dryer.
  2. Attach the air tube to the J 22124-B pressure gage on the side opposite the toggle valve.
  3. Close the toggle valve.
  4. Apply service air pressure to the service valve and pressurize until the J 22124-B pressure gage reads 550 kPa (80 psi).
  5. Verify that the system maintains pressure for at least 1 minute. If the system does not maintain the specified pressure for the specified amount of time, check the shock absorber air sleeves, air tubes, and all connections for air leaks using a soapy water solution. Repair or replace any leaking components.
  1. «Air Tube Repair»(/chevrolet/avalanche/ii-2006-2013/remont/electronic-suspension/#suspension-control-system-suspension-leveling__air-tube-repair)
  2. «Shock Absorber Replacement (1500)»(/chevrolet/avalanche/ii-2006-2013/remont/suspension-rear/#rear-suspension-system) or «Shock Absorber Replacement (2500)»(/chevrolet/avalanche/ii-2006-2013/remont/suspension-rear/#rear-suspension-system)
  1. Perform the «Diagnostic System Check - Vehicle (with HP2)»(/chevrolet/avalanche/ii-2006-2013/remont/oem-general-information/#vehicle-diagnostic-information-2-of-2__diagnostic-system-check-vehicle-with) or «Diagnostic System Check - Vehicle (without HP2)»(/chevrolet/avalanche/ii-2006-2013/remont/oem-general-information/#vehicle-diagnostic-information-2-of-2__diagnostic-system-check-vehicle-without) prior to using this diagnostic procedure.
  2. Review «Strategy Based Diagnosis»(/chevrolet/avalanche/ii-2006-2013/remont/oem-general-information/#vehicle-diagnostic-information-2-of-2__strategy-based-diagnosis) for an overview of the diagnostic approach.
  3. «Diagnostic Procedure Instructions»(/chevrolet/avalanche/ii-2006-2013/remont/oem-general-information/#vehicle-diagnostic-information-2-of-2__diagnostic-procedure-instructions) provides an overview of each diagnostic category.
CircuitShort to GroundOpen/High ResistanceShort to VoltageSignal Performance
Automatic Level Control Exhaust Solenoid Control CircuitC0660 06C0660 06C0660 01
Automatic Level Control Exhaust Solenoid Supply Voltage CircuitC0660 06C0660 06
Automatic Level Control Relay Coil Control CircuitC0712 06C0712 06C0712 01
Automatic Level Control Relay Coil Supply Voltage CircuitC0712 06C0712 06
Automatic Level Compressor Control Circuit221
Automatic Level Control Compressor Ground Circuit2
1. Rear of Vehicle High 2. Rear of Vehicle Low

The Automatic Level Control (ALC) System uses the electronic suspension control module (ESCM), level sensors, compressor, and exhaust valve to increase or decrease air pressure in the system to control trim height. Battery voltage is supplied to the exhaust valve and compressor relay. The ESCM controls the ground circuits that activate the exhaust valve and compressor relay which maintain trim height based on the level sensor input voltage.

Performing the Suspension Position Calibration (Without Z95) or Suspension Position Calibration (With Z95) procedure may correct the condition.

Schematic Reference

Connector End View Reference

Description and Operation

Electrical Information Reference

  1. «Circuit Testing»(/chevrolet/avalanche/ii-2006-2013/remont/ignition-switchsteering-lock/#wiring-systems-and-power-management-service-troubleshooting-diagnosis__circuit-testing)
  2. «Connector Repairs»(/chevrolet/avalanche/ii-2006-2013/remont/ignition-switchsteering-lock/#wiring-systems-and-power-management-service-troubleshooting-diagnosis__connector-repairs)
  3. «Testing for Intermittent Conditions and Poor Connections»(/chevrolet/avalanche/ii-2006-2013/remont/ignition-switchsteering-lock/#wiring-systems-and-power-management-service-troubleshooting-diagnosis__testing-for-intermittent-conditions-and-poor)
  4. «Wiring Repairs»(/chevrolet/avalanche/ii-2006-2013/remont/ignition-switchsteering-lock/#wiring-systems-and-power-management-service-troubleshooting-diagnosis__wiring-repairs)

Scan Tool Reference

Control Module References for Scan Tool Information

Ignition ON, command the exhaust valve solenoid ON and OFF with a scan tool. Listen for the exhaust valve clicking.

  1. Ignition OFF, disconnect the harness connector at the ALC compressor.
  2. Ignition ON, verify that a test lamp illuminates between the ALC compressor connector B+ circuit terminal B and ground. If the test lamp does not illuminate, test the B+ circuit for a short to ground or an open/high resistance. If the circuit tests normal and the ESC/ALC EXH fuse is open, test the exhaust valve control circuit for a short to ground. If all circuits test normal, test or replace the ALC compressor.
  3. Connect a test lamp between the ALC compressor connector control circuit terminal C and the B+ circuit terminal B.
  4. Command the exhaust valve solenoid ON and OFF with a scan tool. The test lamp should turn ON and OFF when changing between the commanded states. If the test lamp is always ON, test the control circuit for a short to ground. If the circuit tests normal, replace the ESCM. If the test lamp is always OFF, test the control circuit for an open/high resistance. If the circuit tests normal, replace the ESCM.
  5. If all circuits test normal, test or replace the ALC compressor.

Perform the Diagnostic Repair Verification after completing the diagnostic procedure.

  1. «Air Compressor Replacement»(/chevrolet/avalanche/ii-2006-2013/remont/electronic-suspension/#suspension-control-system-suspension-leveling)
  2. «Suspension Position Calibration (Without Z95)»(/chevrolet/avalanche/ii-2006-2013/remont/electronic-suspension/#suspension-control-system-suspension-leveling) or «Suspension Position Calibration (With Z95)»(/chevrolet/avalanche/ii-2006-2013/remont/electronic-suspension/#suspension-control-system-suspension-leveling)
  3. «Control Module References»(/chevrolet/avalanche/ii-2006-2013/remont/communication-devices/#programming-and-setup-all-systems__control-module-references) for electronic suspension control module (ESCM) replacement, programming and setup
  1. Perform the «Diagnostic System Check - Vehicle (with HP2)»(/chevrolet/avalanche/ii-2006-2013/remont/oem-general-information/#vehicle-diagnostic-information-2-of-2__diagnostic-system-check-vehicle-with) or «Diagnostic System Check - Vehicle (without HP2)»(/chevrolet/avalanche/ii-2006-2013/remont/oem-general-information/#vehicle-diagnostic-information-2-of-2__diagnostic-system-check-vehicle-without) prior to using this diagnostic procedure.
  2. Review «Strategy Based Diagnosis»(/chevrolet/avalanche/ii-2006-2013/remont/oem-general-information/#vehicle-diagnostic-information-2-of-2__strategy-based-diagnosis) for an overview of the diagnostic approach.
  3. «Diagnostic Procedure Instructions»(/chevrolet/avalanche/ii-2006-2013/remont/oem-general-information/#vehicle-diagnostic-information-2-of-2__diagnostic-procedure-instructions) provides an overview of each diagnostic category.
CircuitShort to GroundOpen/High ResistanceShort to VoltageSignal Performance
Automatic Level Control Exhaust Solenoid Control CircuitC0660 06C0660 06C0660 01
Automatic Level Control Exhaust Solenoid Supply Voltage CircuitC0660 06C0660 06
Automatic Level Control Relay Coil Control CircuitC0712 06C0712 06C0712 01
Automatic Level Control Relay Coil Supply Voltage CircuitC0712 06C0712 06
Automatic Level Compressor Control Circuit221
Automatic Level Control Compressor Ground Circuit2
1. Rear of Vehicle High 2. Rear of Vehicle Low

The Automatic Level Control (ALC) System uses the electronic suspension control module (ESCM), level sensors, compressor, and exhaust valve to increase or decrease air pressure in the system to control trim height. Battery voltage is supplied to the exhaust valve and compressor relay. The ESCM controls the ground circuits that activate the exhaust valve and compressor relay which maintain trim height based on the level sensor input voltage.

Inspect for the following conditions

  1. Leaking lines or components-Perform the «Automatic Level Control System Leak Test»(/chevrolet/avalanche/ii-2006-2013/remont/electronic-suspension/#suspension-control-system-suspension-leveling) and «Air Compressor Leak Test»(/chevrolet/avalanche/ii-2006-2013/remont/electronic-suspension/#suspension-control-system-suspension-leveling__air-compressor-leak-test) as necessary.
  2. Performing the «Suspension Position Calibration (Without Z95)»(/chevrolet/avalanche/ii-2006-2013/remont/electronic-suspension/#suspension-control-system-suspension-leveling) or «Suspension Position Calibration (With Z95)»(/chevrolet/avalanche/ii-2006-2013/remont/electronic-suspension/#suspension-control-system-suspension-leveling) procedure may correct the condition.

Schematic Reference

Connector End View Reference

Description and Operation

Electrical Information Reference

  1. «Circuit Testing»(/chevrolet/avalanche/ii-2006-2013/remont/ignition-switchsteering-lock/#wiring-systems-and-power-management-service-troubleshooting-diagnosis__circuit-testing)
  2. «Connector Repairs»(/chevrolet/avalanche/ii-2006-2013/remont/ignition-switchsteering-lock/#wiring-systems-and-power-management-service-troubleshooting-diagnosis__connector-repairs)
  3. «Testing for Intermittent Conditions and Poor Connections»(/chevrolet/avalanche/ii-2006-2013/remont/ignition-switchsteering-lock/#wiring-systems-and-power-management-service-troubleshooting-diagnosis__testing-for-intermittent-conditions-and-poor)
  4. «Wiring Repairs»(/chevrolet/avalanche/ii-2006-2013/remont/ignition-switchsteering-lock/#wiring-systems-and-power-management-service-troubleshooting-diagnosis__wiring-repairs)

Scan Tool Reference

Control Module References for Scan Tool Information

Ignition ON, command the compressor relay ON and OFF with a scan tool. Listen for the compressor running or relay clicks.

  1. Ignition OFF, disconnect the ALC relay.
  2. Ignition ON, verify that a test lamp does not illuminate between the relay connector control circuit terminal 86 and ground. If the test lamp illuminates, test the control circuit for a short to voltage.
  3. Verify that a test lamp illuminates between the relay connector B+ circuit terminal 85 and ground. If the test lamp does not illuminate, test the B+ circuit for a short to ground or an open/high resistance. If the circuit tests normal and the ESC/ALC EXH fuse is open, test the relay coil B+ circuit for a short to ground. If all circuits test normal, test or replace the ELC relay.
  4. Verify that a test lamp illuminates between the relay connector B+ circuit terminal 30 and ground. If the test lamp does not illuminate, test the B+ circuit for a short to ground or an open/high resistance. If the circuit tests normal and the ALC/COMP fuse is open, test the compressor control circuit for a short to ground. If all circuits test normal, test or replace the ALC compressor.
  5. Disconnect the harness connector at the air compressor.
  6. Test for less than 2 ohms between the ALC compressor ground circuit terminal G and ground. If greater than the specified value, test the ground circuit for an open/high resistance.
  7. Connect the harness connector at the ALC compressor.
  8. Connect a 40A fused jumper wire between the relay connector B+ circuit terminal 30 and the control circuit terminal 87. Verify the ALC compressor is activated. If the ALC compressor does not activate, test the control circuit for an open/high resistance. If the circuit tests normal, test or replace the ALC compressor.
  9. Connect a test lamp between the relay connector B+ circuit terminal 85 and the control circuit terminal 86.
  10. Command the ALC compressor relay ON and OFF with a scan tool. The test lamp should turn ON and OFF when changing between the commanded states. If the test lamp is always ON, test the control circuit for a short to ground. If the circuit tests normal, replace the ESCM. If the test lamp is always OFF, test the control circuit for a short to voltage or an open/high resistance. If the circuit tests normal, replace the ESCM.
  11. Test the ELC relay. If the ELC relay fails the component test, replace the relay.
  12. Ignition OFF, disconnect the harness connector at the ALC compressor.
  13. Ignition ON, verify that a test lamp illuminates between the ALC compressor connector B+ circuit terminal B and ground. If the test lamp does not illuminate, test the B+ circuit for a short to ground or an open/high resistance. If the circuit tests normal and the ESC/ALC EXH fuse is open, test or replace the ALC compressor.
  14. Connect a test lamp between the ALC compressor connector control circuit terminal C and the B+ circuit terminal B.
  15. Command the exhaust valve solenoid ON and OFF with a scan tool. The test lamp should turn ON and OFF when changing between the commanded states. If the test lamp is always ON, test the control circuit for a short to ground. If the circuit tests normal, replace the ESCM. If the test lamp is always OFF, test the control circuit for an open/high resistance. If the circuit tests normal, replace the ESCM.
  16. If all circuits test normal, test or replace the ALC compressor.

Relay Test

  1. Ignition OFF, disconnect the relay.
  2. Test for 50-200 ohms between terminals 85 and 86. If the resistance is not within the specified range, replace the relay.
  3. Test for infinite resistance between the following terminals: 30 and 86 30 and 87 30 and 85 85 and 87 If not the specified value, replace the relay.
  4. Install a 20 amp fused jumper wire between relay terminal 85 and 12 volts. Install a jumper wire between relay terminal 86 and ground. Test for less than 2.0 ohms between terminals 30 and 87. If greater than the specified range, replace the relay.

Perform the Diagnostic Repair Verification after completing the diagnostic procedure.

  1. «Relay Replacement (Attached to Wire Harness)»(/chevrolet/avalanche/ii-2006-2013/remont/ignition-switchsteering-lock/#wiring-systems-and-power-management-introduction) or «Relay Replacement (Within an Electrical Center)»(/chevrolet/avalanche/ii-2006-2013/remont/ignition-switchsteering-lock/#wiring-systems-and-power-management-introduction)
  2. «Air Compressor Replacement»(/chevrolet/avalanche/ii-2006-2013/remont/electronic-suspension/#suspension-control-system-suspension-leveling)
  3. «Suspension Position Calibration (Without Z95)»(/chevrolet/avalanche/ii-2006-2013/remont/electronic-suspension/#suspension-control-system-suspension-leveling) or «Suspension Position Calibration (With Z95)»(/chevrolet/avalanche/ii-2006-2013/remont/electronic-suspension/#suspension-control-system-suspension-leveling)
  4. «Control Module References»(/chevrolet/avalanche/ii-2006-2013/remont/communication-devices/#programming-and-setup-all-systems__control-module-references) for electronic suspension control module (ESCM) replacement, programming and setup

Automatic Level Control (ALC) Trimset Procedure

If the system is functioning abnormally, performing the ALC Trimset recalibration procedure may correct the condition. When a system component has been replaced, ALC Trimset calibration must be performed. In the scan tool Special Functions menu, select ALC Trimset and follow the screen prompts to perform the procedure. Once the process has been completed, the system should be fully functional.

If the system is functioning abnormally, performing the Bumpstop and ALC Trimset recalibration procedures may correct the condition. When a system component has been replaced, the Bumpstop setup and ALC Trimset procedures must be performed.

  1. Place the vehicle on a flat level surface. Ensure that the suspension is in the normal resting position. With a scan tool, perform the ALC Trimset procedure by following the screen prompts.
  2. Raise the vehicle off the ground enough to allow the suspension to fully extend. With a scan tool, perform the suspension Bumpstop setup procedure by following the screen prompts.

Once the process has been completed, the system should be fully functional.

Removal Procedure

  1. Remove the automatic level control air compressor from the vehicle. Refer to «Air Compressor Replacement»(/chevrolet/avalanche/ii-2006-2013/remont/electronic-suspension/#suspension-control-system-suspension-leveling) .
  2. Clean the area around the connection of the automatic level control air dryer to the automatic level control air compressor body.
  3. Disconnect the electrical connector from the pressure sensor.
  4. Remove the air dryer/pressure sensor assembly retaining screw.
  5. Push the air dryer/pressure sensor assembly in while rotating the air dryer/pressure sensor assembly clockwise until the assembly detaches from the automatic level control air compressor body.
  6. Remove the automatic level control air dryer from the automatic level control air compressor.

Installation Procedure

  1. Install the automatic level control air dryer to the automatic level control air compressor.
  2. Push the air dryer/pressure sensor assembly in while rotating the air dryer/pressure sensor assembly counterclockwise until the assembly attaches to the automatic level control air compressor body.
  3. Install the air dryer/pressure sensor assembly retaining screw.
  4. Connect the electrical connector to the pressure sensor.
  5. Install the automatic level control air compressor to the vehicle. Refer to «Air Compressor Replacement»(/chevrolet/avalanche/ii-2006-2013/remont/electronic-suspension/#suspension-control-system-suspension-leveling) .

Air Tube Repair

  1. Locate the leaking area with soap and water or a stethoscope.
  2. Before removing the air tube, perform the following procedures. Turn the ignition ON, with the engine OFF. Install a scan tool. With the scan tool, exhaust the air from the system for at least 60 seconds.
  3. Cut and remove the leaking line (2) section.
  4. Remove the plastic retainer pin from one of the nuts.
  5. Slide the air line tube onto the nut until the line bottoms in the rubber seal (5).
  6. Hold the air line tube in position. Tighten: Tighten the air line tube repair nut to 8 N.m (70 lb in).
  7. Install the air line tube to the other end of the coupling.
  8. Repeat Steps 3 through 5.
  9. Install the air line tube to the vehicle.
  10. Ensure that the vehicle is on level ground and perform the following steps. Turn the ignition ON, with the engine OFF. Install a scan tool. With the scan tool, operate the air compressor for 30 seconds or until the rear of the vehicle begins to rise. Remove the scan tool. Cycle the ignition OFF, then back On, with the engine ON to allow the air suspension system to regain the desired rear suspension position.
  1. Raise and support the vehicle. Refer to «Lifting and Jacking the Vehicle»(/chevrolet/avalanche/ii-2006-2013/remont/hoistjack/#general-information) .
  2. Before removing the air tubes, perform the following steps: Turn the ignition On, with the engine OFF. Install a scan tool. With the scan tool, exhaust the air from the system for at least 60 seconds.
  3. Disconnect the air tube (1) from the air dryer.
  4. Disconnect the electrical connection (2).
  5. Remove the air inlet and hose (1) from the fuel filler neck bracket.
  6. Loosen the mounting nuts.
  7. Slide the air compressor (2) rearward to clear the frame slots.
  8. Remove the air compressor from the vehicle.
  1. Install the air compressor (2) to the vehicle.
  2. Slide the air compressor forward to secure the fasteners into the frame slots and install the mounting nuts. Tighten the bolts to 15 N.m (11 lb ft)
  3. Install the air inlet hose (1) to the fuel filler neck bracket.
  4. Connect the air tube (1) to the air dryer.
  5. Connect the electrical connection (2).
  6. Lower the vehicle.
  7. perform the following procedure after the air compressor has been replaced. Turn the ignition ON, with the engine OFF. Install a scan tool With the scan tool, operate the air compressor for 30 seconds or until the rear of the vehicle begins to rise. Remove the scan tool. Cycle the ignition OFF, then back ON, with the engine ON to allow the air suspension system to regain the desired rear suspension position.

Automatic Level Control Description and Operation

Note. In addition to level control, vehicle may also be equipped with suspension dampening (RPO Z95). See ELECTRONIC SUSPENSION CONTROL .

The automatic level control (ALC) system maintains a desired rear suspension position under all types of towing, hauling, and loading conditions.

The system uses the electronic suspension control module (ESCM), ELC relay, ALC compressor assembly, air dryer, air lines, shock absorbers with integral air chambers, suspension position sensors, exhaust valve, driver information center (DIC), and the serial data circuit to perform the system functions.

When the vehicle is unloaded, the rear suspension is at a desired position, which is monitored by the ESCM using the position sensor signal voltage inputs. As weight is added to the rear of the vehicle, the position sensor's signal voltage inputs change. When the ESCM detects a steady substantial change in the position sensor signal voltages for at least 10 seconds, it responds by commanding ON the ELC relay, which activates the compressor causing the air pressure in the shock absorber chambers to inflate. This inflation raises the rear of the vehicle to regain the desired suspension position. When weight is removed from the vehicle, the ESCM responds by commanding ON the exhaust valve causing the air pressure in the shock absorber chambers to deflate. This deflation lowers the vehicle to regain the desired suspension position.

The compressor is a positive displacement piston air pump driven by a 12-volt DC permanent magnet motor. The compressor draws filtered air through an intake line attached to an under body rail. The compressed air is then run through a dryer containing a moisture-absorbing chemical that dries the compressed air before it is sent to the shock absorber chambers. Each time the compressor is activated, the ESCM commands ON the exhaust valve for 1.5 seconds to release air from the compression chamber in the compressor's cylinder head ensuring low motor current draw upon compressor activation. The ESCM also limits the amount of compressor run time to 255 seconds to protect the compressor components from thermal damage.

The system also performs a self test on each ignition ON cycle in which the ESCM commands the ELC relay ON, activating the compressor for 4 seconds then monitors the position sensor's signal voltage inputs to verify the compressor is functioning and the system is holding air pressure.

The ESCM has the ability to detect malfunctions within the ALC system. Any malfunctions detected will cause the DIC to display the SERVICE SUSPENSION SYSTEM message. For more information on other functions of the ESCM, refer to Electronic Suspension Control Description and Operation .

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