Air ride

Here are the test procedures for the air ride suspension system:

TEST H: AIR SUSPENSION LEFT REAR OR RIGHT REAR CORNER UP TIMEOUT

Connect New Generation Star (NGS) tester. Trigger VDM Active Command COMPRESSR ON then OFF. If air compressor turns on and then off, go to next step. If compressor does not turn on and off, go to TEST U .
Using NGS tester, trigger VDM Active Command RRSOL or LRSOL and COMPRESSR ON. If corner of vehicle raises, trigger VDM Active Command RRSOL or LRSOL and COMPRESSR Off and go to next step. If corner of vehicle does not raise, trigger VDM Active Command RRSOL or LRSOL and COMPRESSR Off and go to TEST V .
Check all height sensor mounting points. Check for proper height sensor installation and for damaged mounting points. If installation and mounting points are okay, go to next step. If installation and/or mounting points are worn or damaged, repair as necessary. Clear DTCs. Adjust riding height. See RIDE HEIGHT under ADJUSTMENTS & INSPECTION.
Using NGS tester, trigger VDM Active Command HGT POWER ON. Monitor VDM PID LR_HGT or RR_HGT. Disconnect suspect height sensor from lower ball stud. Extend and compress height sensor through full rage of travel. If NGS display length for sensor changes as sensor is moved, trigger VDM HGT POWER OFF. Reconnect sensor. Perform ACCURATE TRIM TEST using NGS tester. Clear DTCs. If NGS display length for sensor does not change as sensor is moved, trigger VDM HGT POWER OFF. Reconnect height sensor. Go to TEST O .
TEST I: AIR SUSPENSION LEFT REAR OR RIGHT REAR CORNER DOWN TIMEOUT

Connect New Generation Star (NGS) tester. Trigger VDM Active Command RRSOL or LRSOL and VENT ON. If corner of vehicle lowers, trigger VDM Active Command RRSOL or LRSOL and VENT OFF and go to next step. If corner of vehicle does not lower, trigger VDM Active Command RRSOL or LRSOL and VENT OFF and go to step 4) .
Check all height sensor mounting points. Check for proper height sensor installation and for damaged mounting points. If installation and mounting points are okay, go to next step. If installation and/or mounting points are worn or damaged, repair as necessary. Clear DTCs. Adjust riding height. See RIDE HEIGHT under ADJUSTMENTS & INSPECTION.
Using NGS tester, trigger VDM Active Command HGT POWER ON. Monitor VDM PID LR_HGT or RR_HGT. Disconnect suspect height sensor from lower ball stud. Extend and compress height sensor through full rage of travel. If NGS display length for sensor changes as sensor is moved, replace VDM. Adjust riding height. See RIDE HEIGHT under ADJUSTMENTS & INSPECTION. If NGS display length for sensor does not change as sensor is moved, trigger VDM HGT POWER OFF. Reconnect height sensor. Go to TEST O .
Disconnect air line from air compressor and air spring solenoid. Connect a vacuum pump to one end of disconnected line. Apply vacuum. If vacuum does not hold, reconnect line and go to next step. If vacuum holds, service pinched or obstructed air line as necessary. Clear DTCs.
Using NGS tester, trigger VDM Active Command LR SOL or RR SOL ON. If air exhausts from suspect solenoid, go to next step. If air does not exhaust, replace suspect solenoid. Clear DTCs.
Remove air drier from air lines and compressor. Blow compressed shop air into air line port of drier. If air freely exits drier, replace compressor assembly. Clear DTCs. If air does not freely exit drier, replace drier assembly. Clear DTCs.
TEST V: AIR SUSPENSION INOPERATIVE, ONE OR MORE CORNERS LOW & COMPRESSOR OPERATES

Disconnect air line from air compressor drier and air spring solenoid. Connect a vacuum pump to one end of disconnected line. Apply vacuum. If vacuum does not hold, go to next step. If vacuum holds, service pinched or obstructed air line as necessary. Repeat on-demand self-test and pneumatic test.
Cap both air lines at air spring. Connect a vacuum pump to air line at air drier. Apply vacuum. If vacuum holds, go to next step. If vacuum does not hold, repair leak in air line as necessary. Recheck system operation.
Reconnect air lines at air springs. Connect New Generation Star (NGS) tester. Connect shop air to air line at air drier. Using tester, trigger VDM Active Command LR SOL and RR SOL ON. If both air springs inflate and full suspension travel is reached, go to next step. If air springs do not inflate and/or full suspension travel is not reached, replace air spring solenoid. Recheck system operation.
CAUTION: In following step, DO NOT run air compressor for more than 3 minutes as compressor may overheat.
Disconnect air compressor relay connector. Connect fused (60-amp) jumper wire between Light Blue/Pink and Violet/Orange wire terminals of relay connector. Pressure should reach 150 psi (10.5 kg/cm2 ). Disconnect jumper wire. Pressure should hold steady. Trigger VDM Active Command VENT ON. If pressure remains steady, system is okay. If pressure does not remain steady, replace air compressor. Recheck system operation.

Please let us know what you find.

Cheers, Ken