Town Car air suspension problems? Read this thread!

[dumpsterguy840]

My 2005 Town car rear suspension sinks as I drive down the road, I stop and get out and check it out and it raises as I watch it. I drive down the road and it sinks again. I'm looking for tips on how I can start narrowing down what the culprit is.

 

[Town]

When driving your car down the road the air suspension module waits 45 seconds from the time the height sensor indicates a low or high condition to the time the module switches on the compressor and opens the air spring solenoids. The reason for this is that the suspension is always moving up and down so changing the air pressure frequently is not desirable. When the car is stationary the module reacts immediately to the height sensor indicating a low or high condition.

The most common reason for the air suspension to lose air is a leak in the air spring(s). Usually this is noticed when the car is left for a long time, such as overnight. It is normal for the suspension to vent about an inch after about an hour (according to Ford but my car takes much longer) to vent. So letting the car sit overnight with the suspension switched off will not allow the springs to be vented and stay at same height. If there is a drop in rear suspension height then there is probably a spring or spring solenoid leak. Have you noticed the suspension being low in the morning? When you put the key in the ignition and turn it on the air suspension module raises the car to trim height and that only takes a few seconds.

You verify if your springs are leaking by switching off the suspension as soon as you get home (suspension at trim height) and then measuring the distance from ground to the rear fender lip, it should be around 19" or so. In the morning the distance should still be the same (or settled a 1/4" due to friction in shocks and suspension mountings). If the suspension has dropped an inch or more then jack up the rear (suspension switch still off) and spray soapy water all over the rubber bladder of the spring(s), usually the lower part has cracks that leak. The spring solenoids are mounted at the top of the springs and pointing toward the back seat at a bit of an angle and they should also be sprayed with soapy water if the springs do not have air leaks.

Let us know what you find. Good luck.

 

[dumpsterguy840]

Town car has been sitting still with the switch off for close to 15 hours and she has not dropped at all. Is it safe to assume I do not have a leak?

 

[Town]

Town car has been sitting still with the switch off for close to 15 hours and she has not dropped at all. Is it safe to assume I do not have a leak?

Yes, I would say you don't have a leak with the air springs themselves and the spring solenoids must be sealing too. Can you leave the car for a long time with the suspension switched on to see if there is a leak. In that case there would be a short or suspension module problem venting the system (opening spring solenoids and the vent solenoid).

Did you measure the height of the fender lip from the ground? Just to confirm the suspension height sensor is apparently OK.

Good luck.

______________________________

 

[dumpsterguy840]

She sat again all last night and she hasn't dropped a millimeter. Funny timing as I have an appt. to take her in this morning for a steering column recall. Is it safe to drive with the air suspension switch off?

 

[Town]

She sat again all last night and she hasn't dropped a millimeter. Funny timing as I have an appt. to take her in this morning for a steering column recall. Is it safe to drive with the air suspension switch off?

Yes you can drive the car with the suspension switched off. Many people have done that. I don't think the car needs to be raised to do the recall but you might want to let the tech know the suspension is off, in case he switches it back on to raise the vehicle.

Good luck.

 

[dumpsterguy840]

the dealer said they do a $110 computer check to narrow down air suspension issue. He also said it could be an intermitent leak? Im here now and will keep you posted, I always get nervous at the dealer!

 

[Town]

An intermittent leak would likely be due to the suspension module or sensor problem. I don't see how a leak in the air spring bladder could be intermittent.

The $110 computer check is probably going to look for DTC codes in the suspension module. I think there may be a self test that can be performed using the Ford scanner. You may want to ask them what exactly is done for $110.

Good luck.

______________________________

 

[dumpsterguy840]

diagnosis is bad sensor on the right hand side, part is $270, with install and diagnosis total of five hundred seventy dollars. did I do the right thing?

 

[Town]

That sounds expensive for the part. I assume the sensor is the height sensor on the rear suspension, but I thought that was on the left side (driver side) on rear suspension. A diagnosis is almost always the right thing. If you can do the replacement yourself it will be cheaper. The procedure to replace the height sensor is in the Lincoln Tech forum here: http://www.lincolnforums.com/forums...sion-height-sensor-replacement-and-adjustment

Good luck.

 

[dumpsterguy840]

Murphys law got me again. I took the shortcut had the dealer do the job for 500 plus dollars. I woke up this morning and the car is as low to the ground as she can get. I started her up and I could hear the pump run but the car does not raise.

 

[dumpsterguy840]

I called the dealer and asked if I could speak with the mechanic and was politely told no. I booked it in for tomorrow morning. I'm if I shoulf jack her up for an inspection before I do that?

______________________________

 

[Town]

The process to raise the rear of your car begins with the air suspension module receiving a voltage signal from the height sensor that the suspension is below trim height (i.e. voltage greater than 2.8 volts of trim height) and then starts the compressor and then opens both air spring solenoids. It appears the height sensor is sending the low suspension signal voltage and the compressor is started but either the air spring solenoids are not opening or the air springs are collapsed too much. So I would jack the rear end up on both sides just a few inches and see if the suspension raises. You should be able to drive to the dealer with the suspension collapsed.

Sounds to me that there was a mis-diagnosis since it is hard to believe the height sensor is faulty or was not installed correctly. So your problem may be the air suspension module being faulty rather than the height sensor. But I don't know.

Good luck.

 

[dumpsterguy840]

any idea how much that module costs and is it an easy or difficult installation?

 

[Town]

No, I don't know the cost of the module or the height sensor. The module replacement is easy since it is located behind the glove box and is removed to replace the actuator for the HVAC air inlet door (recirc door). The procedure is in the Lincoln Tech forum for replacement of the recirc door actuator here: http://www.lincolnforums.com/forums/threads/10513-Town-Car-HVAC-recirc-door-actuator-replacement see post #3.

I will see what I can find using my VIN on the parts cost from Ford. I could not see anything on RockAuto. A used suspension module may work but the 2003 and up models seem to have more difficulty in doing that compared to the earlier models.

Good luck.

 

[Town]

The suspension module for my 2007 model is called the Electronic suspension control module and is available from Tasca Ford (online) here: http://www.fordparts.com/Default.aspx?gnav=nav:home for $172.30 while the suspension height sensor called Suspension self levelling sensor and bracket is $231.97 all prices may be in Canadian dollars so the US price may be less. Your 2005 model should use the identical parts.

People have had good results from this site, but I have no experience.

Good luck.

______________________________

 

[dumpsterguy840]

I took the car in today and they could not find anything else wrong with it, they readjusted the height sensor and all I can do now is wait till the morning and see if the car is still off the ground. Thank you so much for all your help so far, I have a feeling I'll need those links someday and maybe tomorrow.

 

[dumpsterguy840]

2 hours later I checked the height and she dropped a 1/2 inch, I started her up, the compressor kicked in and she sank to the ground?

I switched the system off in the trunk and turned her back on 1 minute later. After several minutes the compressor kicked in and she lifted to full height and I promptly turned off the system, I am sure she will be at the same height position in the morning.

Here is what I have so far:
Air backs that won't deflate when the system is turned off but will deflate with the system turned on. (turning off the system and turning it back on corrects this problem, at least until I park it for awhile)
A newly installed suspension height sensor that has been re-checked and operating properly
Dealers computer tester was not able to do an auto check on the system as it had trouble communicating with the system control module even after the dealer uploaded and installed new updates to their system while working on my car. The dealer was able to run that system in a manual mode checking one component at a time and everything checked out successful.
I'm not a rocket scientist but my gut feeling tells me the system control module is faulty? (which means I just switch out the control module?)
My second choice would be a faulty air spring solenoid? (which means I have to determine which one is faulty?)

Any feedback would be great, thanks

 

[Town]

I agree with your diagnosis, based upon the following info.

Here is what the 2007 Ford Service Manual says about the "Self Test" feature in the Symptom Chart of the Diagnostic & Testing section of the Dynamic suspension chapter:

"Unable to enter self-test for Air suspension module

If the scan tool cannot communicate with the air suspension module, REFER to Section 418-00 to diagnose the no communication problem. If the scan tool can communicate with the air suspension module, INSTALL a new air suspension module. REFER to Air Suspension Module in this section."

I read section 418-00 and it identifies possible causes for non-communication of scan tool to the suspension module. If after all the tests are completed satisfactorily and the scan tool still fails to communicate with the air suspension module then replace the module. So the word in red appears wrong and should be "cannot".

Since the dealer's scanner cannot enter self test with the suspension module then likely the module is faulty and needs to be replaced. It does not appear that the suspension module needs to be programmed so you should be able to install a new or used module yourself. Attached is the procedure.

Good luck.

 

[dumpsterguy840]

I tried to buy the suspension module from anywhere but Ford/Lincoln but none of the auto parts stores could even find it in their parts catalogs. So I bit the bullet and paid $200.00 to Ford for the part. Easy to replace, drop the glove box (no tools needed) 2 screws that held it in and two wiring harness plugs that were easy to unplug. After installing the new module I let the car sit over night with the system turned on and in the morning she was still at the same height so it appears that the problem has been solved. Thanks for all your help on this and hopefully someone who has a similar problem can find this thread and save themselves some time and money.