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HDGene, ASE Certified Technician
Category: Lincoln
Satisfied Customers: 5511
Experience:  25 year ASE Master Technician & Advanced Drivability L1 Certified Ford Senior Master Technician
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Air suspension issue. 2006 Lincoln Navigator. Compressor

Customer Question

Air suspension issue. 2006 Lincoln Navigator. Compressor runs but immediately exhausts from passenger side. It's almost as if the passenger side shock is running backward. New compressor, front sensors, front solenoids. Pneumatic test passed.
Submitted: 1 year ago.
Category: Lincoln
Customer: replied 1 year ago.
Also, compressor runs even when doors are open.
Expert:  HDGene replied 1 year ago.

Hello, were there any codes stored in the air suspension system? its possible the air bag is leaking on the strut depending on where its leaking air out of the right side system or is it blowing out the vent on the compressor?

Customer: replied 1 year ago.
The last codes were C1991 or C1990. I cant remember which.
When I took the vehicle to the dealership, they said they weren't getting signal from any of the sensors, and that those would need to be replaced. They were not very helpful. The system holds pressure if it is inflated with a pump. The relief valve seems to be venting.
Expert:  HDGene replied 1 year ago.

Ok and now that you have replaced these parts do you still have the same codes. Is the right side height sensor installed properly and reading the correct height voltage or is it reading too high and trying to lower the right front? It shouldnt run with the door open just go to a kneel position

Customer: replied 1 year ago.
Sometimes it will run constantly and not inflate the system. Sometimes it will cycle on for a few moments , which is followed immediately by an audible, but low whooshing sound. The system has not been rechecked for codes after replacing those parts. However , the behavior of the system is exactly the same.
Expert:  HDGene replied 1 year ago.

ok, you need to isolate the air leak. There are o rings inside the strut to seal the airbag on the front struts and the struts do go bad. Need to concentrate on air leaks first then re evaluate the system using a scan tool to run it through its system diagnostics

Customer: replied 1 year ago.
All the o rings have been replaced . The entire system passed leak test. If it helps, before the compressor was replaced, only the rear would stay constantly inflated. At the shop, the compressor would cycle on and off but the relief valve would stay open. They assumed some communication error related to the C1991 code. I took the vehicle home, disconnected the battery and jacked up the vehicle. After some tinkering, I dropped the vehicle a little faster than I would have liked, and after starting, the system worked perfectly.
Customer: replied 1 year ago.
The next morning both the front and the rear were sitting down and the cycling compressor symptoms started again.
Customer: replied 1 year ago.
due to the intermittent nature of function, and the compressor pumping while door is open, I hypothesized 4WAS problem or a circuit/grounding issue.
Expert:  HDGene replied 1 year ago.

Possible, but if you hear the system audibly venting air you need to isolate that area first and rerun a diagnostic on the system,It should hold air overnight

Customer: replied 1 year ago.
When it vents, it seems to be coming from the compressor itself, and the bags do not visibly inflate. They guys at the shop had the same issue. They tested the system for leaks starting at the first T connector and could find none. I will inflate it later and see if it still holds.
Expert:  HDGene replied 1 year ago.

Then it sounds like it is being commanded to vent since it vent the air from the system at the compressor. Definitely need to rerun a complete system diagnostic and check ride height measurements and pneumatic tests on the system to re evaluate its operation. A ride height sensor might be not installed properly or not adjusted correctly and giving a false reading, making it vent the system

Customer: replied 1 year ago.
The sensor problem is interesting. The symptoms were the same before and after replacing the front sensors. However, I noticed that both the front sensors were identical. The replacement ones were different from each other. The new LF sensor had a bracket that was perpendicular to the mount while the RF bracket was parallel and the same as both the old ones. Are they supposed to be identical? All of the parts places show two different brackets. Also, both the old sensors had freely moving arms.
Expert:  HDGene replied 1 year ago.

Yes they should mount in the same manner as the original equipement. if the sensor is mounted to high it can think the ride height is too high and cause the system to vent. All voltage readings should be the same from left front to right front and the rear. The rear is adjustable.

Expert:  HDGene replied 1 year ago.

Hi, do you still need help with this concern?

Customer: replied 1 year ago.
Hi HDGene, sorry about the delay in response. I was out of town for vacation and did not have access to the vehicle in question.
Customer: replied 1 year ago.
The control module was replaced and all the pneumatic tests were passed. The system does not have leaks. The solenoids all respond.
The problem remains that the system vents ALL the air out before any real inflation can be seen.The system cannot be calibrated and the scan tool is giving the same c1991 error. The mechanic says that the control module needs to be programmed, but according to the tech documents, the modules are programmed at the factory and should only need adjustments and calibration.
What could be causing this venting and communication error?
Expert:  HDGene replied 1 year ago.

A problem with the network or issue with one of the electronic air suspension componets being shorted and not allowing communciation if you cant communicate with the module, blown fuse, bad relay etc.