SUSPENSION AIR SUSPENSION SYSTEM Article No. OVERVIEW DIAGNOSIS/SCAN TOOL 03-13-2 INFORMATION DTC S C1990 AND C1991 COMPRESSOR NOISE ELECTRICAL AIR SUSPENSION SYSTEM OVERVIEW DIAGNOSIS/SCAN TOOL INFORMATION DTC S C1990 AND C1991 COMPRESSOR NOISE FORD: 2003 EXPEDITION LINCOLN: 2003 NAVIGATOR ISSUE 3. Each air spring has a solenoid that must open This article is being published as a diagnostic aid to to vent or compress. supplement the existing Workshop Manual 4. The air suspension compressor has a vent diagnostics (see items A through F under solenoid that must open to vent the system. CONTENTS). This article will also address the proper procedure to clear Diagnostic Trouble Codes 5. The transition from trim height to kneel height (DTC s) C1990 or C1991 from the Vehicle or from kneel height to trim height takes Dynamics Module (VDM)/4-Wheel Air Suspension approximately 30 to 45 seconds. Module (4WAS). ACTION 6. The front air springs are independently controlled. The rear air springs are always Refer to the following diagnostic aid and Service controlled as a pair. Tips for complete air suspension overview and to 7. The system will not operate with any doors help properly diagnose the system. open, with the liftgate open, with the liftgate SERVICE INFORMATION glass open or with the power running boards extended. CONTENTS A: Brief description of suspension operation 8. The air suspension switch position is ignored above 15 mph. The air suspension will be B: Diagnostic tools active over 15 mph, regardless of the switch C: Diagnosis of leaky air spring solenoids position. D: Compressor noise 9. Kneel Mode is defined as 25mm below Trim E: C1990 and C1991 DTC s Mode. F: Compressor relay change - Vehicles built after February 3, 2003 10. Trim Mode is defined as normal driving height. A: AIR SUSPENSION SYSTEM OVERVIEW 11. 4X4 Off-Road Mode is engaged when the vehicle is in 4X4 Low at a speed of less than 1. Vehicle height is controlled by the 4-Wheel Air 19 MPH, and is defined as 25mm above trim Suspension Module (4WAS) based on height height. sensor output voltages. 2. The Vehicle Dynamics Module (VDM) and the 4-Wheel Air Suspension Module (4WAS) are the same module. This was a naming convention change in mid-model year 2003. : The information in Technical Service Bulletins is intended for use by trained, professional technicians with the knowledge, tools, and equipment to do the job properly and safely. It informs these technicians of conditions that may occur on some vehicles, or provides information that could assist in proper vehicle service. The procedures should not be performed by do-it-yourselfers. Do not assume that a condition described affects your car or truck. Contact a Ford, Lincoln, or Mercury dealership to determine whether the Bulletin applies to your vehicle. Copyright 2003 Ford Motor Company PAGE 1
12. Height Sensor Operation There are 3 height sensors - Left Front, Right THE WDS MUST BE USED TO CLEAR A B2477 Front, and Right Rear. DTC IN A NAVIGATOR 4WAS MODULE. The sensor output ranges between 0.5 volts and 4.5 volts. The Left Front and Right Front sensors are opposite in polarity. The voltage output of the sensors decreases as the vehicle body rises and increases as the vehicle body lowers. THE UBP CABLE (ROTUNDA 105-100) MUST BE USED WITH THE NGS TO COMMUNICATE WITH THE VDM/4WAS MODULE. (THE WDS DOES NOT REQUIRE A SPECIAL CABLE TO COMMUNICATE WITH THE VDM/4WAS MODULE.) 13. Ride Height Change Triggers 2. For NGS Classic software releases prior to When the ignition key is in the Run position August 2003, the NGS can be used for all and the vehicle is shifted to either Drive or diagnostic and service functions on the 4WAS Reverse, the ride height will change from module except for Module Configuration, which Kneel to Trim. downloads the VAPS curve and clears the B2477 code. The NGS can be used for ride When the ignition key is in the Off position height programming with the service (green) and the doors are closed after being open, card version 11.2 or higher and the UBP cable. the ride height will change from Trim to Kneel. 3. For NGS+ software releases after August 2003, When the vehicle is engaged into 4X4 LOW, the NGS can be used for all diagnostic and the ride height will change to Off-Road. service functions on the 4WAS module. B: DIAGNOSTIC TOOLS (NGS AND WDS) DO NOT REPLACE THE VDM/4WAS CONTROL 1. The VDM/4WAS module communicates with the MODULE (3C142) SIMPLY BECAUSE THE network via the UBP protocol. This ABOVE SYMPTOMS EXIST, SINCE THE communication protocol can occasionally result CONTROL MODULE IS NOT THE CAUSE. in slow communication with the New Generation Star (NGS) or Worldwide Diagnostic System C: DIAGNOSIS OF INTERMITTENT AND/OR (WDS) tools. This may make the diagnostic UNEXPECTED RIDE HEIGHT BEHAVIOR tools appear sluggish or appear to lock up 1. Leaky air spring solenoids usually result in occasionally during diagnostic use or idle intermittent and/or unexpected ride height periods. In order to minimize the likelihood of behavior. The vehicle may not have been slow response or tool lock-up, the following is driven long enough to set a pneumatic failure recommended: DTC (C1725 and/or C1726) in the VDM/4WAS Minimize the number of viewed PIDs as module, and the warning message may or may much as possible while using active not be turned on during system malfunction. commands or PID monitoring/data recording. Take care to give the tool time to react, as 2. Leaky air spring solenoids do not leak to the responses may be slow. atmosphere, but instead to the airlines within the system. Inability of the solenoids to stop air flow will usually be apparent immediately after WDS SOFTWARE VERSIONS PRIOR TO B25 they are commanded to close. (RELEASE DATE MID-MAY 2003) DO NOT SUCCESSFULLY TEST THE AIR SUSPENSION 3. Some symptoms of leaky air spring solenoids SYSTEM. BE SURE THAT THE WDS IS are the following: UPDATED TO VERSION B25 OR LATER PRIOR TO PERFORMING AIR SUSPENSION a. Front end low and rear end high. DIAGNOSTICS. WDS VERSION B25 CAN BE b. One corner drops more than it should during USED FOR ALL DIAGNOSTIC AND SERVICE a height change process or while vehicle is FUNCTIONS ON THE 4WAS MODULE. parked. PAGE 2
c. Rear end high and front end near or at c. Replace the leaking solenoid or solenoids normal height. with a revised part 2L1Z-5311-AA. d. Front end low and rear end near or at normal height. WHEN REPLACING A LEAKING SOLENOID, CHECK THE SOLENOID DATE CODE ON THE SIDE OF THE NEW SOLENOID BODY. THE DATE ANY OF THE PREVIOUS ISSUES MAY BE CODE, SHOWN IN STAMPED LETTERS IN INTERMITTENT IN OCCURRENCE. JULIAN FORMAT, SHOULD BE ON OR LATER THAN 0363. IF IT IS EARLIER THAN THIS DATE, DO NOT RECALIBRATE RIDE HEIGHTS SIMPLY THE SOLENOID IS SUSPECT AND SHOULD NOT BECAUSE THE RIDE HEIGHTS APPEAR BE USED ON THE VEHICLE. INCORRECT. INCORRECT RIDE HEIGHTS ARE ONLY A SYMPTOM OF A DIFFERENT SYSTEM d. Retest for leaky solenoids. PROBLEM AND DO NOT INDICATE A NEED FOR e. Road test the vehicle to ensure a robust RIDE HEIGHT CALIBRATION. ALL RIDE repair. HEIGHTS ARE 100% SET DURING VEHICLE MANUFACTURE AND WILL NOT CHANGE OVER D: COMPRESSOR NOISE TIME. RIDE HEIGHT CALIBRATION IS ONLY Excessive compressor noise can be caused by a NEEDED WHEN A HEIGHT SENSOR OR AIR loose compressor-to-body mounting, compressor SUSPENSION CONTROL MODULE HAS BEEN ground-outs, or loose parts (bolts, nuts, etc.) on or REPLACED. underneath the compressor assembly. Compressor 4. Diagnosis Steps: noise is NOT usually corrected by replacing the compressor assembly itself. a. Disconnect and remove the airline union at the midpoint of the right hand frame rail The compressor does make an audible noise that near the body mount. Pressure will be can be heard during cycling of the system. Normal relieved in 3 to 5 seconds. operation is characterized by a moderate humming or buzzing sound from under the hood during compressor operation. WHEN THE SPRING SOLENOIDS ARE OPEN, Perform the following actions before replacing any THE VEHICLE WILL LOWER QUICKLY. compressor for a noise complaint: b. Verify that the air suspension solenoids 1. Check to make sure the three attachment bolts close properly: are securely fastened to the body (Figure 1). Using the NGS (or WDS Software version B25 or 2. Make sure that no parts are trapped under or later), cycle each air spring solenoid (LF, RF, LR, on the compressor bracket. RR) one at a time from open (on) to closed (off). Air should flow from the open air line when the 3. Make sure that the compressor motor assembly solenoid is opened, and should stop when the is not in contact with any surrounding solenoid is closed. After closing the solenoid, cap component that could cause vibration noises. the open line with your thumb to see if the air continues to be released from the air spring. A 4. Ensure that the compressor is free to move in buildup of pressure in the line (i.e., all spring its rubber mounting grommets. Make sure the solenoids are off and the compressor is not compressor bracket has not been bent or running) identifies a leaking solenoid(s). CYCLE deformed in any way that would load the rubber EACH SOLENOID SEVERAL TIMES AS THE PROBLEM MAY BE INTERMITTENT. mounts against each other. PAGE 3
E: CLEARING C1990 AND C1991 DTCS 6. Run the pneumatic test. Due to vehicle network issues, the NGS may drop out before the test These codes must be cleared or the Check completes. When this occurs, rerun the Suspension warning message will be turned on. pneumatic test with no one in or on the vehicle. All service modules are built with the C1990 If the test has been running for 5 minutes or code. All assembly plant modules are built with more, the NGS has dropped out. The tester will the C1991 code. These codes can only be indicate if the vehicle has passed the test. cleared using the following procedures. C1990 and C1991 can be re-enabled in the control module by resetting the ride heights to PASSAGE OF THE PNEUMATIC TEST DOES their default value, or when the pneumatic test NOT ELIMINATE THE POSSIBILITY OF has failed. When either one of these DTC s are MALFUNCTIONING SOLENOID VALVES. present, the air suspension warning will be 7. After passage of the pneumatic test, use NGS enabled. Diagnostic Card (redcard) version 22 or later Clearing C1990 or C1991 (or WDS Software version B25 or later) to retrieve any DTCs. If C1990 or C1991 is present, go to Step 8 and calibrate the ride BEFORE PROCEEDING WITH THE FOLLOWING heights. Otherwise, go to Step 10. STEPS, ENSURE THAT THE SYSTEM IS FULLY 8. Using the NGS Service Card (green card) FUNCTIONAL. THE VEHICLE MUST PASS THE software version 11.2 or later, or WDS software PNEUMATIC TEST AND HAVE ALL THREE RIDE version B25 or later, manually raise and lower HEIGHT SENSORS CALIBRATED FOR THESE the vehicle to the correct ride height as defined CODES TO CLEAR. in Workshop Manual Section 204-05 on an 1. Either start the vehicle or put vehicle on a alignment machine and calibrate the ride battery charger to ensure sufficient battery heights. voltage. 2. Vent the vehicle down to the kneel position. MANUAL SEND MODE ON THE NGS WORKS (Having the key off, transmission in park, air BETTER THAN THE AUTO SEND MODE. (NOT suspension switch on and all openings, doors APPLICABLE TO NGS GREEN CARD 11.2.) and liftgate glass closed will make the vehicle kneel.) 9. Using the NGS Diagnostic Card (red card) version 22 or later, retrieve the DTCs and verify that all DTCs have been cleared. DO NOT SIT IN THE VEHICLE DURING THIS 10. Drive vehicle and verify the repair. Verify the PROCESS. THE VEHICLE MAY NOT KNEEL OR Check Suspension message is gone. Make MAY KNEEL VERY LITTLE IF THE HEIGHT OF the system vent to kneel and pump to trim THE VEHICLE IS NEAR THE KNEEL POSITION. several times while verifying system function. 3. Pump the vehicle to the current calibrated trim F: COMPRESSOR RELAY CHANGE - VEHICLES height by turning the key to run, shifting to BUILT AFTER FEBRUARY 3, 2003 drive, and then returning to park and closing all vehicle openings (message center should show Navigator vehicles built prior to February 3, 2003 no openings ajar). Vehicle will then pump to the use a solid-state relay for the air suspension currently calibrated trim height. compressor motor. The control line from the module is grounded to energize the relay. The relay is 4. Connect the NGS or WDS to the vehicle (make located on the radiator support on the right side just sure that the UBP cable is used if the NGS is behind the headlamp assembly. the tool being utilized). 5. Using the NGS Service Card (green card) software version 11.2 or later, or WDS software version B25 or later, command the pneumatic test. PAGE 4
Both Navigator and Expedition vehicles equipped with air suspension built since February 3, 2003 utilize a mechanical relay for the compressor motor. The control line from the module is grounded to energize the relay. The relay is located on the compressor bracket just above the compressor attachment to the radiator support on the right side. In addition, there are important wiring differences between the two relays. Early production vehicle relays have one power feed, where late production relays have two (both are hot at all times). The solid-state relay also employs an external full-time ground, where the mechanical relay does not. See Figure 2 for more details. PART NUMBER 2L1Z-5311-AA PART NAME Solenoid - Air Suspension OTHER APPLICABLE ARTICLES: NONE WARRANTY STATUS: INFORMATION ONLY Figure 1 - Article 03-13-2 PAGE 5
Figure 2 - Article 03-13-2 PAGE 6