Diagnostic Instructions
| • | Perform the Diagnostic System Check - Vehicle prior to using this diagnostic procedure. |
| • | Review Strategy Based Diagnosis for an overview of the diagnostic approach. |
| • | Diagnostic Procedure Instructions provides an overview of each diagnostic category. |
Diagnostic Fault Information
Circuit | Short to Ground | Open/High Resistance | Short to Voltage | Signal Performance |
|---|---|---|---|---|
Air Suspension Compressor Assembly Battery Positive Voltage | 2, and 4 | 2, and 4 | -- | -- |
Air Suspension Compressor Assembly Ground | -- | 2, and 4 | -- | -- |
Air Suspension Inflator Switch Ground | -- | 2 and 4 | -- | -- |
Air Suspension Inflator Switch Indicator Control | 2 | 2 | 1 | -- |
Air Suspension Inflator Switch Signal | 3 | 4 | 4 | -- |
1. Air Suspension Inflator Switch Indicator Always ON 2. Air Suspension Inflator Switch Indicator Inoperative 3. Inflator Always ON 4. Inflator Inoperative 5. Inflator Will Operate While Vehicle is in Motion | ||||
Circuit/System Description
The air suspension system has the feature to utilize the air compressor as a compressed air source. When the air suspension inflator switch is activated the compressor receives a ground signal requesting compressor activation. The compressor then applies voltage to the indicator control circuit illuminating the indicator. Upon compressor activation, supplied air pressure is then diverted from the air suspension to the air supply access port.
Reference Information
Schematic Reference
Connector End View Reference
Description and Operation
Air Suspension Description and Operation
Electrical Information Reference
Circuit/System Verification
Ignition ON, observe the air suspension inflator switch parameter while pressing/depressing the inflator switch. The scan tool inflator switch indicator scan tool data should read ON/OFF and OFF/ON and the air compressor should activate supplying air pressure to the air accessory port.
Circuit/System Testing
- Ignition OFF, disconnect the air suspension inflator switch harness at the air suspension compressor assembly.
- Test for less than 2 ohms between the ground circuit connector X452, terminal B and ground.
- Perform the air suspension inflator switch component test.
- Ignition ON, connect a fused jumper between Connector X451 terminal B3 (ASCM compressor relay control) at the air suspension compressor assembly and ground. Verify that the compressor operates.
- Ignition ON and the fused jumper still connected, verify that a test lamp illuminates between the air suspension inflator switch indicator control circuit terminal C (SUV) or terminal A (SUT) and ground.
| ⇒ | If the compressor continues to run, test or replace the air suspension compressor assembly. |
| ⇒ | If greater than the specified value, test the air suspension compressor assembly ground circuit for an open/high resistance. If the circuit tests normal, replace the air suspension compressor assembly. |
| ⇒ | If the air suspension inflator switch fails the component test, replace the switch. |
| ⇒ | If the compressor does not operate, test the ECAS relay B+ supply circuit for an open/high resistance or short to ground. If all circuits test normal, test or replace the air suspension control module. |
| ⇒ | If the test lamp does not illuminate, test or replace the air suspension control module. |
| ⇒ | If the test lamp illuminates, test the indicator control circuit for an open/high resistance, short to ground, or a short to voltage. If the circuit tests normal, replace the air suspension inflator switch. |
Component Testing
Air Suspension Inflator Switch
- Ignition OFF, disconnect the harness connector X451 at the air suspension compressor assembly.
- Test for infinite resistance between the air suspension inflator switch signal terminal C (SUV) or terminal A (SUT) and the ground terminal B with the switch in the OFF position.
- Test for less than 2 ohms between the signal terminal C (SUV) or terminal A (SUT) and the ground terminal B with the switch in the ON position.
| ⇒ | If not the specified value, replace the air suspension inflator switch. |
| ⇒ | If greater than the specified value, replace the air suspension inflator switch. |
Repair Instructions
Perform the Diagnostic Repair Verification after completing the diagnostic procedure.
