Can anyone tell me what signals the air compressor to kick in? Is it the air shock solenoid?

My '04 Navi's air compressor will not turn on. I have read 15 pages of posts and have not read anything that matches my symptoms. It just so happened two days after I replaced my front right air shock assembly I ordered from www.arnottindustries.com. Everything was working fine for two days, then without warning, the air compressor stopped running. Arnott said it is not related to the air shock replacement, so I have moved on.

The relay for my compressor sits on top of the compressor. I put in a new relay but it did not help. I checked all the fuses I could find listed in the operator's manual. I ran a jumper wire at the relay socket to check for power and the compressor started running but did not air up the suspension. I pulled the air line off the front of the compressor/dryer assembly to check for pressure and it is putting out air but will not air up the suspension. It seems a vent must be open. All the air bags are deflated and the navi is sitting on the rubber bumpers. I can't raise the navi up off the frame bumpers even with the jumper in place.

My scan tool showed no faults. I tried clearing any possible computer faults not shown by disconnecting the battery, turning the key on and touching the battery cables together, then turning the key off and reconnecting the battery, no difference.

There has to be something more. Any ideas what to try next?<O</O

 

There is so much to check on these trucks when things like this happens. First you should disconnect the negatve terminal at the battery for a minute or so to clear any system codes, reconnect the battery and check to verify the air ride switch is on. Then turn the key on to run and start the engine. Open and close the driver door twice being sure all the other doors are closed while the engine is running. You should then hear the compressor start after a few seconds and the truck will start to lift in stages. This has worked for me in the past. Let us know your results.

 

Mel, I have tried all you mentioned. Disconnected both battery cables, verified the air ride switch was on, closed doors, nothing I have tried works.

I wonder what signals the relay to trip and power up the compressor motor?

 

If you jumped the relay and the motor powered up, the problem is elsewhere in the system.
Here's the info from my Manual, I hope it helps.

SECTION 204-05B: Vehicle Dynamic Suspension — 4-Wheel 2000 Expedition/Navigator Workshop Manual

GENERAL PROCEDURES

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Ride Height Adjustments

Special Tool(s) Worldwide Diagnostic System (WDS)
418-F224

New Generation STAR (NGS) Tester
418-F052 or equivalent scan tool


Inflation and Deflation of the Air Suspension System

WARNING: Do not remove an air spring under any circumstances when there is pressure in the air spring. Do not remove any components supporting an air spring without either exhausting the air or providing support for the air spring to prevent vehicle damage or personal injury.

WARNING: Disconnecting an air line that is connected to the air compressor can cause personal injury or damage to components as high pressure air is vented uncontrolled.

Turn the air suspension switch on.
Turn the ignition switch to the RUN position.
Connect scan tool to the data link connector (DLC).
Select Air Suspension Control Module under Active Command Mode:
VENT FRNT to deflate the front down.
LIFT FRNT to inflate the front up.
VENT REAR to deflate the rear down.
LIFT REAR to inflate the rear up.

Calibration


Front Ride Height Resetting — Clear B2140 DTC

Turn the ignition key OFF and turn it back to RUN; exit the vehicle, close all doors and allow the system to vent the vehicle down to kneel height (approximately 30 seconds).
Connect scan tool to the data link connector (DLC).
Select the proper vehicle year, model and engine type.
Select 4WAS-AIR SUSP/EVO (4x2 and 4x4) module.
Select "Parameter Reset Command (Clear Ride Height) under Active Command Modes" menu, trigger through the warning messages and reset (trigger from OFF to ON):
scan tool version 10.0 — "Front" and "Rear."
scan tool version 11.0+ — "Front CLR."
Back out the torsion bar adjustment bolt (approximately 40 mm from the bolt head to the bottom surface of the torsion bar adjuster).
Deflate the front air shocks by using the scan tool "Vent Front" command in "Air Suspension Control" menu (should take about 30 seconds), and jounce the front of the vehicle to fully lower the front of the vehicle.
Adjust and measure the vehicle ride height; refer to Section 204-01B .
NOTE: Do not save rear ride heights. The air suspension control module has precalibrated values already stored. Refer to Rear Ride Height Mechanical Resetting.

Select the "Save Calibration Values (Store Ride Height)" scan tool command to calibrate the air suspension control module. Trigger through the warning message(s) and save "FRONT" (trigger from OFF to ON).

Rear Ride Height Mechanical Resetting

Turn the ignition key ON.
Connect scan tool to the data link connector (DLC).
Select the proper vehicle year, model and engine type.
Select 4WAS-AIR SUSP/EVO (4x2 and 4x4) module.
Measure vehicle rear height (driver side) from the bottom of the frame to the rear jounce bumper bolt rear side of head base.

Using scan tool, adjust rear height to 146.8 ± 2 mm by moving the rear of the vehicle down using the active command ("VENT_REAR") or by moving the rear of the vehicle up ("LIFT_REAR") in PID RHGTSEN.
Monitor the rear height sensor voltage on the right side of the scan tool screen.
Loosen the ball stud nut on the rear air suspension height sensor bracket and adjust it by moving it with the air suspension height sensor up or down until the voltage is 2.66 ± 0.02 volt.
Tighten the ball stud nut.


Rear Ride Height Electronic Resetting

Connect scan tool to the data link connector (DLC).
Turn the ignition switch to the RUN position.
Select the proper vehicle year, model and engine type.
Select 4WAS-AIR SUSP/EVO (4x2 and 4x4) module.
Select the active commands menu "Save Calibration (Store Ride Height)." Trigger through the warning message.
Monitor the RHGTSEN PID.
NOTE: Do not press the trigger after selecting REAR.

Select REAR.
NOTE: Do not disconnect the rear height sensor from the upper ball stud.

Disconnect the rear height sensor from the lower ball stud.

Slowly compress/extend the rear height sensor until the rear height sensor voltage is 2.66 ± 0.02 volts.
Press the trigger to save rear ride height settings (turn from OFF to ON); this will calibrate the air suspension control module.
Perform the Rear Ride Height Mechanical Resetting. If the rear height mechanical resetting has been performed, clear DTCs and run On-Demand Self-Test.

 

Thanks for the effort Mel. I agree, the problem is some place else other than the compressor motor.

The special tools required in your Manual's instructions, WDS and NGS, are tools the dealership would have but I was trying to avoid them. As is, all my air shocks are already deflated all the way down. That's the problem.

I was hoping someone would know what component or combination of components send a signal to the relay to trip and run the motor.

 

What does your message center on the dash say regarding air suspension system.?

 

You can disconnect the rear height sensor at the top mount and compress it, it's like a hood strut, and have someone turn the key to the run position and close the driver's door. If you hear a click up front the compressor should then come on. If you hear nothing you could extend the sensor all the way out you should hear a click at one or both of the rear air spring solenoids as it will be trying to vent the springs.
Check that while I type some more.

 

There are 3 solenoids for the rear springs, 1 at the top of each air spring and another on the frame rail under the passenger rear door which sends air to the rear. The ones on the air springs have 2 functions, to allow more air into the spring and to allow the spring to vent as needed. The system has 1 more solenoid on the top of the frame under the fan and shroud and is near impossible to see with the fan snd shroud in place and even harder to change out. Ther is also a coupler or connector over the steering shaft and steering box, this coupler is a known failure point. Mine broke a few weeks ago and the break was hardly visible just by looking at it but, when it was handled it came apart. The Ford replacement part is #2L1Z-5B322-AA andis more substantial as well as easy to replace. There is another known failure point in the air line under the battery box and related mess. apparently the battery acid corrodes the air line over time.
Hope some of this helps.

 

Years ago I had problems with my Mark VIII's air suspension and I rigged up a jumper to open the air valve/solenoid and then inflated the suspension via a remote filler I rigged up in the trunk. It was a PIA but, I maintained my air suspension until I accumulated the parts needed to convert it to springs. I changed it to coils and have been satisfied with the results but I wish I still had the air ride. When the air ride is right it is great and when it's not it's horrible. I converted mine before there were kits to do the conversion and did it because I was more than 200 miles from home in Florida and I drove it home on the bottom, that was not a happy day. I was hoping for a drunk or someone to run into my Mark long before I got home. Any way that's history, I still have my Mark VIII and like it more now than before.
Let us know how things are going with it and if you fix the problem.

 

My message center says "check air suspension".

It's dark and getting late so I'll have to crawl under another day. Because all the air is already out, I will have to jack it up. Do you think it will be ok to do so with the system switch on?

 

Fuses in the CJB "central junction box"-Test fuses f2.27, F2.20, these are for the air suspension module. Test Fuses F2.11 and f2.111, these are for the compressor relay. Test for continuity thru the service disconnect switch.The 4WAS must see the switch is turned on. The 4WAS module "4 wheel air suspension" module (also called the VDM) completes the "ground" to energize the air suspension relay, turning on the compressor and at the same time opening the air springs to fill. The relay should have power at all times at Pk/lb and lb/pk wires. The db/ye wire is the controlled ground by the air suspension module to energize the relay. The shop manual says if the power and grounds are ok and the module will not communicate with the scan tool to replace the module. You would have to pin out the wires and confirm they are ok. Your scan tool may only read generic OBDII engine codes and not factory specific body/suspension systems. Cycle your service disconnect switch several times. They don't get much use and maybe the contacts are dirty. Hope this helps.

 

Thanks Moto Mel,
You were right on with the air line connector over the steering box. It had one cracked and when I put soapy water on the connector to check for leaks, it came apart. I have replaced the connector and Bingo, it's back on the road - cheap.
Thanks again.

 

All my fuses were good and I cycled the service disconnect switch several times. No change.

I ended up taking it to dealer for diagnosis. They wanted to replace the rt frt height sensor, the air compressor, and calibrate the system for some $1400 plus. I let them replace the height sensor for $540. When I picked it up the compressor was working fine and I have been driving it for a week with no problems, so I guess the culprit was the rt frt height sensor.

I thought I might put in a new compressor myself at some point for about $200 but what does calibrating the system do for me? They want $120 to do it after I put in a compressor.

 

I can't say for sure but I think it's just smoke and mirrors. When I first got my Navigator running, I bought it with a bad engine, it had some issues with the air suspension. After checking everything visible and replacing the suspension module with no real change I just drove it for a few days and apparently the system recalibrated itself. No further problems except for a noisey compressor and when I replaced the rubber mounts it got quiet again. It has been operating just as it is supposed to ever since. In my opinion the height sensors do not go bad unless they get damaged. They will get out of adjustment and cause problems until they are re-adjusted.

Quite a few here call the dealers "Stealerships" and at times with just cause.

Should you ever have problems that seem insurmountable you should check out American Air Suspension's web site great help in trouble shooting and good prices on whatever you need.

 

What does recalibrating even mean? How do you know when it's happened, or not happened?

My rt frt has always sagged slightly, maybe and inch or so. I thought for $540 it might at least get level.

I saved the old height adjuster just in case I need it for future use.

My current compressor is aftermarket, I think from "Arnott Industries" and is still working but I ordered a replacement from "American Air Suspension" just to have. Price was good but I was not to excited about having to return my used compressor within 30 days to receive their 2 yr. warrantee. I would much rather keep it in stock until the one I have gives up the ghost. They didn't specify that the return need be original equipment so I hope there is no problem.