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 |
|---|---|---|---|---|
Ignition 3 Voltage | 1, 3 | 1, 3 | -- | -- |
Air Suspension Dump Valve Solenoid Control | 1, 3 | 1, 3 | 2, 4 | -- |
Air Suspension Dump Valve Solenoid Ground | -- | 1 | -- | -- |
Air Suspension Dump Indicator Ground | -- | 3 | -- | -- |
1. Suspension Always High 2. Suspension Always Low 3. Air Suspension Switch Indicator Inoperative 4. Air Suspension Switch Indicator Always ON | ||||
Circuit/System Description
Voltage is applied to the air suspension dump switch when the ignition switch is in RUN. When the air suspension dump switch is manually activated, voltage is then applied to the air suspension dump solenoid. The air suspension dump solenoid will be energized until the air suspension dump switch is manually deactivated. The air suspension dump indicator lamp receives the same voltage signal from the air suspension dump switch as the dump solenoid when it is activated. Both the switch indicator and dump valve solenoid have separate chassis grounds.
Diagnostic Aids
| • | Verify that the air supply system is operating properly. |
| • | Inspect for leaks or damage to the supply lines or height sensor. |
Reference Information
Schematic Reference
Connector End View Reference
Description and Operation
Air Suspension Description and Operation
Electrical Information Reference
Circuit/System Verification
Ignition ON, toggle the air suspension dump switch ON and OFF. The air suspension dump indicator and dump solenoid should turn ON and OFF.
Circuit/System Testing
- Ignition OFF, disconnect the harness connector at the air suspension dump valve solenoid.
- Ignition OFF, test for less than 1.0 ohm between the ground circuit terminal B and ground.
- Connect the harness connector at the dump valve solenoid harness connector. Disconnect the harness connector at the air suspension dump switch
- Ignition ON, verify that a test lamp illuminates between the ignition circuit terminal A and ground.
- Verify that a test lamp does not illuminate between the control circuit terminal C and ground.
- Connect a 10-amp fused jumper between the ignition circuit terminal A and control circuit terminal C. Verify that the dump valve solenoid is activated.
- Ignition OFF, test for less than 1.0 ohm between the ground circuit terminal F and ground.
- Ignition ON, connect a 10-amp fused jumper between the ignition circuit terminal A and control circuit terminal C. Verify that a test lamp illuminates between the control circuit terminal D and ground.
- If all circuits test normal, test or replace the air suspension dump switch.
| ⇒ | If greater than the specified range, test the ground circuit for an open/high resistance. |
| ⇒ | If the test lamp does not illuminate, test the ignition circuit for a short to ground or open/high resistance. If all circuits test normal, replace the HYD/AIR BRK 10A circuit breaker. |
| ⇒ | If the test lamp illuminates, test the control circuit for a short to voltage. |
| ⇒ | If the dump valve solenoid does not activate, test the control circuit for a short to ground or an open/high resistance. If the circuit tests normal, test or replace the air suspension relief valve assembly. |
| ⇒ | If greater than the specified range, test the ground circuit for an open/high resistance. |
| ⇒ | If the test lamp does not illuminate, test the control circuit for an open/high resistance. If the circuit tests normal, test or replace the air suspension dump switch. |
Component Testing
Air Suspension Dump Switch
- Ignition OFF, disconnect the harness connector at the air suspension dump switch.
- Test for infinite resistance between the control terminal C and the ignition terminal A with the switch in the open position.
- Test for less than 5 ohms between the control terminal C and the ignition terminal A with the switch in the closed position.
| ⇒ | If not the specified value, replace the air suspension dump switch. |
| ⇒ | If greater than the specified range, replace the air suspension dump switch. |
Air Suspension Dump Indicator
- Ignition OFF, disconnect the harness connector at the air suspension dump switch.
- Install a 3A fused jumper wire between the control terminal D and 12 volts. Install a jumper wire between the ground terminal F and ground.
- Verify that the air suspension dump indicator illuminates.
| ⇒ | If the air suspension dump indicator does not illuminate, replace the air suspension dump switch. |
Air Suspension Dump Valve Solenoid
- Ignition OFF, disconnect the harness connector at the air suspension dump valve solenoid.
- Test for 38.1-41.3 ohms between the control terminal A and the ground terminal B.
| ⇒ | If not within the specified range, replace the air suspension relief valve assembly. |
Repair Instructions
Perform the Diagnostic Repair Verification after completing the diagnostic procedure.
