Air Suspension Symptom Diagnosis

AIR SUSPENSION SYMPTOM DIAGNOSIS

Condition	Possible Source	Action
CHECK AIR RIDE is Displayed in Less Than 5 Seconds After Vehicle is Started	Control module detects an electrical concern before a leveling correction is attempted.	RETRIEVE the DTC that caused CHECK AIR RIDE to actuate from control module memory. (Run FUNCTION TEST 211). RUN the AUTO TEST to see what DTCs are currently seen by the control module. SERVICE current DTC. SERVICE DTC 25, 50 through 95 first. SERVICE DTC 98 and 99 second. SERVICE DTC 29 and 45 third. SERVICE DTCs stored in control module memory if different from Auto Test DTCs. NOTE: If no DTCs are retrieved and CHECK AIR RIDE is constantly displayed, a concern may exist with Circuit 419 (DG/LG) or the message center indicator.
CHECK AIR RIDE Displayed at Differing Times. No Apparent Sequence of Events, Random Order	Control module detects either an electrical concern or encounters excessive correction time while attempting to level vehicle. Will occur most frequently at: Start up if vehicle is sitting low Approximately 65 mph (104 km/h) when control module attempts to lower vehicle 20 mm (0.75 inch) Approximately 35 mph (56 km/h) when control module attempts to raise vehicle 20 mm (0.75 inch)	RETRIEVE DTCs stored in control module memory. (Run FUNCTION TEST 211.) RUN AUTO TEST . SERVICE current concerns. SERVICE concerns from control module memory not already addressed.
CHECK AIR RIDE Not Displayed. One or More Corners High or Low	System inactive and cannot turn on CHECK AIR RIDE display.	WARNING: DO NOT ATTEMPT TO RESET RIDE HEIGHT UNTIL THE SYSTEM PASSES THE AUTO TEST AND DISPLAYS CODE 11 OR THE MANUAL TEST CODES 29 OR 45 TO PREVENT DAMAGE. RUN AUTO TEST . If no DTCs are output, GO to TEST A and TEST C .
	System operating correctly, ride height out of adjustment. Air suspension height sensor popped off ball stud.	If the vehicle passes the Auto Test with a DTC 11, or the manual test DTCs 29 or 45 and one or more corners appear high or low, ADJUST ride height. REFER to RIDING HEIGHT ADJUSTMENT procedure under Adjustments.
One or More Corners Drop Overnight. Vehicle Achieves Trim When Ignition Switch Turned to RUN	A large drop in temperature overnight causes the air in the air springs to contract. This will cause lowering of vehicle corners, and is normal.	RETRIEVE stored DTCs. (Run FUNCTION TEST 211).
	A minor leak in either air springs or spring solenoid valve. This may trigger a DTC 98 if the leak is severe enough to cause excessive compressor run time before trim is reached.	If DTC 98 is retrieved from control module memory, GO to DTC 98 .
One or More Corners Low and CHECK AIR RIDE Displayed 90 Seconds to 2 Minutes After Starting Engine	Control module has detected excessive correction time. This is caused by either: Compressor will not operate A large air leak in either the compressor, air springs or the air lines	RETRIEVE DTC causing CHECK AIR RIDE to be displayed (Run FUNCTION TEST 211). This should be DTC 99. CHECK for compressor and/or air line leaks using DTC 99 and PROCEED to other tests as required.
Front Air Springs are Completely High and/or Rear Air Springs are Completely Low. CHECK AIR RIDE Displayed 45 to 90 Seconds After Starting Vehicle One Front Corner is Completely Low. CHECK AIR RIDE Displayed 45 to 90 Seconds After Starting Vehicle Rear Air Springs are Completely Low. CHECK AIR RIDE Displayed 45 to 90 Seconds After Starting Vehicle	Air suspension height sensor is off ball stud.	EXAMINE air suspension height sensor and REINSTALL on ball stud if required.
Air suspension height sensor ground is open on corners that are not trim. Control module does not detect this as an electrical error.		RUN FUNCTION TEST 211 to RETRIEVE stored DTCs.
Wiring harness has intermittent open circuit.	RUN AUTO TEST . SERVICE Auto Test DTCs. If DTC 99 is received from either control module memory or Auto Test, GO to DTC 99 and CHECK for open air suspension height sensor ground. RUN FUNCTION TEST 223, 224 or 225 to test for intermittent air suspension height sensor and wiring concern.
Irregular Air Suspension Operation at Low Temperatures	Moisture frozen in air lines and compressor air drier. NOTE: In severe cases, water will build up in air springs and recontaminate the system.	WARM vehicle to room temperature. DISCONNECT both ends of ALL air lines. BLOW out air lines to dry. REPLACE compressor air drier. It may be required to REMOVE air springs and DRAIN water.
NOTE: Most customers will not be able to detect vehicle lowering at speed but will report very sensitive steering. Air Suspension Does Not Lower at approximately 65 mph (105 km/h) and Power Steering Efforts are Constantly Very Light or Excessive Steering Effort While Making Quick Maneuvers at High Speed	Control module is not receiving vehicle speed sensor signal.	No DTCs will be stored if the control module is not receiving the vehicle speed sensor signal. INSTALL the Super Star II Tester in a manner that will permit driving the vehicle. TURN off the air suspension service switch located in the luggage compartment. RUN FUNCTION TEST 226. DRIVE the vehicle at speeds over 10 mph (16 km/h). Note speed displayed on Super Star II Tester. If no speed is displayed over 10 mph (16 km/h), GO to TEST B . If speed is displayed, RUN AUTO TEST . If DTC 45 is received, REFER to ELECTRONIC in STEERING. If DTC 45 is not received during Auto Test, system is functioning properly.
Customer Complains of Poor Ride Quality, or Vehicle Leans to One Side and Vehicle Passes Auto Test	Air cannot flow freely into or out of one of the rear air springs. A concern with one of the rear air springs may not be detected during the Auto Test. Tire pressure too high.	RUN FUNCTION TESTS 216, 217, 218 and 219 to make sure both rear air springs can be filled or vented. If a concern is suspected, REFER to DTC 99 .
Cannot Retrieve Stored DTCs or Enter Auto Test	Control module is not active due to wiring concern or there is a concern with the New Generation Star or Super Star II Tester circuits.	GO to TEST A and TEST C .
Nothing Seems to be Working Correctly. Cannot Identify the Root Condition. Do Not Know What to Do Next	Intermittent concern with wiring harness, air suspension height sensor actuators or control module. Several conditions existing in a combination that is not covered by normal diagnostics.	PERFORM the Wiring and Circuit Checks. (REFER to QUICK CHECKS WITHOUT SCAN TOOL .) This will help isolate concerns.
Do Not Have a New Generation Star or Super Star II Tester to Retrieve DTCs or Perform Tests	-	PERFORM the Wiring and Circuit Checks to ISOLATE concerns. (REFER to QUICK CHECKS WITHOUT SCAN TOOL .)