Extended ride height (ERH) is used to increase vehicle ground clearance. When the ERH switch is activated the vehicle will raise 2 inches at the rear. The extended ride height will only occur if vehicle speed is less than 64 km/h (40 mph) with the lift gate and all doors closed with the engine running. When the switch is activated the ERH switch indicator will flash while the vehicle is transitioning to extended ride height. When the vehicle reaches extended ride height the ERH switch indicator will be on continuously. The vehicle will return to normal design height when the switch is activated again and the ERH switch indicator will go OFF. The vehicle will automatically return to normal height if vehicle speed increases over 64 km/h (40 mph) and the ERH switch indicator will turn OFF.

Schematic Reference

Air Suspension Schematics

Connector End View Reference

Component Connector End Views

Description and Operation

Air Suspension Description and Operation

Electrical Information Reference

Scan Tool Reference

Control Module References for scan tool information

1. Ignition ON, command the electronic ride height (ERH) Switch Pressed and Released with a scan tool. Verify that the ERH switch LED indicator turns OFF/ON and ON/OFF and that the Compressor turns ON and OFF with each command.

⇒	If the ERH switch LED indicator does not illuminate or illuminates all the time, refer to the Extended Ride Height Switch LED indicator Malfunction.

⇒	If the ERH switch does not change commanded state, refer to Extended Ride Height Switch Malfunction.

2. Ignition ON, command the Compressor Relay ON and OFF with a scan tool. Verify that the compressor turns ON and OFF with each command.

⇒	If the compressor does not operate or operates continuously, refer to Compressor Malfunction.

3. Ignition ON, command the exhaust valve ON and OFF with a scan tool. Verify the exhaust valve clicks with each command.

⇒	If the exhaust valve does not click or the vehicle height does not change, refer to Exhaust Valve Malfunction.

4. Ignition ON, command the LR and RR Control Valves ON and OFF with a scan tool. Verify the control valves click with each command.

⇒	If a control valve does not click or the applicable rear corner height does not change, refer to Control Valve Malfunction.

Extended Ride Height Switch LED Indicator Malfunction

1. Ignition OFF, disconnect the automatic suspension control module (ASCM) harness connector at the electronic ride height ERH switch (accessory switch of the I/P multifunction switch assembly).
2. Test for less than 2.0 ohms between the IP multifunction assembly ground circuit connector X1 terminal 10 and ground.

⇒	If greater than the specified range, test the ground circuit for an open/high resistance.

3. Ignition ON, verify the scan tool ERH Switch Indicator parameter is OFF.

⇒	If not the specified value, test the ASCM ride height active signal circuit terminal A2 for a short to voltage. If the circuit tests normal, test or replace the ASCM.

4. Install a 3A fused jumper wire between the ASCM ERH switch ride height active indicator control signal circuit terminal A2 and the ground circuit connector X1 terminal 10. Verify the scan tool ERH Switch Indicator parameter is ON.

⇒	If not the specified value, test the ASCM ride height active signal circuit for a short to voltage or an open/high resistance. If the circuit tests normal, replace the ASCM.

5. If all circuits test normal, test or replace the ERH Switch.

Extended Ride Height Switch Malfunction

1. Ignition OFF, disconnect the ASCM harness connector at the electronic ride height switch ERH.
2. Ignition ON, verify that a test lamp illuminates between the control circuit I/P Multifunction Switch Assembly Connector X1 terminal 2 and ground.

⇒	If the test lamp does not illuminate, test the control circuit for a short to ground or an open/high resistance. If the circuit tests normal and the control circuit fuse is open, test the signal circuit terminal 4 for a short to ground.

3. Verify the scan tool ERH Switch parameter is Released.

⇒	If not the specified value, test the signal circuit I/P Multifunction Switch Assembly Connector X1 terminal 4 for a short to voltage. If the circuit tests normal, test or replace the air suspension control module (ASCM).

4. Install a 3A fused jumper wire between the signal circuit I/P Multifunction Switch Assembly Connector X1 terminal 4 and the control circuit terminal 2. Verify the scan tool ERH Switch parameter is Pressed.

⇒	If not the specified value, test the signal circuit for an open/high resistance. If the circuit tests normal, replace the ASCM.

5. If all circuits test normal, test or replace the ERH Switch (Rear Air Suspension Control Valve Switch).

Compressor Malfunction

1. Ignition OFF, disconnect the ECAS relay harness at the air compressor.
2. Ignition OFF, test for less than 1 ohm between the ground circuit terminal 86 and ground.

⇒	If greater than the specified range, test the ground circuit for an open/high resistance.

3. Disconnect the harness at the Air Compressor Assembly part of the ASCM.
4. Verify that a test lamp illuminates between the voltage supply circuit terminal 30 and ground.

⇒	If the test lamp does not illuminate, test the voltage supply circuit for a short to ground or an open/high resistance.

5. Verify that a test lamp illuminates between the B+ circuit terminal 87 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 or replace the air compressor assembly.

6. Ignition ON, verify that a test lamp does not illuminate between the control circuit terminal 85 and B+.

⇒	If the test lamp illuminates, test the control circuit terminal 85 for a short to ground.

7. Connect the harness connector at the ASCM.
8. Connect a 3A fused jumper wire between the ground circuit terminal 86 and the control circuit terminal 85. Verify the compressor is activated.

⇒	If it does not activate, test the control circuit for an open/high resistance. If the circuit tests normal test or replace the air compressor assembly.

9. Connect a test lamp between the control circuit terminal 85 and the ground circuit terminal 86.
10. Command the 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 or open/high resistance. If the circuit tests normal, replace the air compressor assembly.

⇒	If the circuit is always OFF, test the control circuit for a short to ground or a open/high resistance. If the circuit tests normal, replace the air compressor assembly.

11. If all circuits test normal, test or replace the ECAS relay.

Exhaust Valve Malfunction

1. Ignition OFF, connect a test lamp between the exhaust valve connector control circuit terminal and the B+ circuit terminal.
2. Ignition ON, command the exhaust valve 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 voltage. If the circuit tests normal, replace the air suspension control module.

⇒	If the test lamp is always OFF, test the control circuit for a short to ground or open/high resistance. If the circuit tests normal, replace the air suspension control module.

3. If all circuits test normal, test or replace the air suspension compressor assembly.

Control Valve Malfunction

1. Ignition OFF, connect a test lamp between the affected control valve connector control circuit terminal and the B+ circuit terminal.
2. Ignition ON, command the affected control valve 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 voltage. If the circuit tests normal, replace the air suspension control module.

⇒	If the test lamp is always OFF, test the control circuit for a short to ground or open/high resistance. If the circuit tests normal, replace the air suspension control module.

3. If all circuits test normal, test or replace the air suspension compressor assembly.

Control Valve, Exhaust Valve, and Compressor

1. Ignition OFF, disconnect the relay.
2. Test for 50-200 ohms between terminals 85 and 86.

⇒	If not the specified value, 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 the resistance is not within the specified range, replace the relay.

4. Install a 20A 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.

Extended Ride Height Switch LED Indicator

1. Ignition OFF, disconnect the harness at the ERH switch (accessory switch-part of the IP multifunction switch assembly).
2. Test for infinite resistance between the I/P multifunction switch assembly ride height active indicator control signal circuit terminal A2 and the I/P multifunction switch assembly ground circuit connector X1 terminal 10 with the switch in the open position (Pressed).

⇒	If not the specified value, replace the ERH switch (accessory switch of the I/P multifunction switch assembly).

3. Test for less than 2 ohms between the signal circuit terminal A2 and the ground circuit connector X1 terminal 10 with the switch in the closed position (Released).

⇒	If not the specified value, replace the ERH switch (accessory switch of the I/P multifunction switch assembly).

4. Test for infinite resistance between each terminal and the ERH switch housing/case.

⇒	If not the specified value, replace the ERH switch (accessory switch of the I/P multifunction switch assembly).

Extended Ride Height Switch

1. Ignition OFF, disconnect the ASCM harness at the ERH switch.
2. Test for infinite resistance between the I/P Multifunction Switch Assembly Connector X1 B+ circuit terminal 4 and the control circuit terminal 2 with the switch in the open position (Released).

⇒	If not the specified value, replace the ERH switch (Rear Air Suspension Control Valve Switch).

3. Test for less than 2 ohms between the I/P Multifunction Switch Assembly Connector X1 B+ circuit terminal 4 and the control circuit terminal 2 with the switch in the closed position (Pressed).

⇒	If not the specified value, replace the ERH switch (Rear Air Suspension Control Valve Switch).

4. Test for infinite resistance between each terminal and the ERH Switch (Rear Air Suspension Control Valve Switch) housing/case.

⇒	If not the specified value, replace the ERH switch (Rear Air Suspension Control Valve Switch).

Perform the Diagnostic Repair Verification after completing the diagnostic procedure.