99 Expedition Air Suspension Problems
 

I posted this originally to the suspension message base but those folks said I should post here since you all would be more familiar with LLS.

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I am having a problem with the air suspension on my 99 Expedition. I bought the truck used a year ago. A friend of mine told me about this forum. Not sure if I should post this to this group or the Expedition board. Here is my problem:

The air suspension does not seem to be working. When I first start the truck, the "Check Suspension" light is *not* lit. After about 5 minutes or so, the light will illuminate.

During this time I do not hear the compressor kick on at all. In the past I could hear the compressor kick on and run, so I know what it "sounds" like. Now, though, I cannot hear the compressor running.

I took the truck to my local Ford dealer in Madison. They charged me a $75 diagnostic fee and told me that I needed a new compressor. They wanted $625 with labor to replace it. Since I'm not totally clueless when it comes to vehicles (and my friend is a big Ford guy who knows how to do all this stuff) I said I would take a pass, figuring I could get a decent aftermarket compressor myself and my friend will help me install it for a case of Sam Adams.

Now, this is where it gets funky. I ordered an aftermarket compressor on Ebay for $200. I go over to my buddy's house, and in 3/4ths of an hour we have the old compressor out and the new one in. Great! I've saved $400!

But wait... I start up the car... and... The compressor doesn't kick in. Same symptom as before (no Check Suspension Light upon vehicle startup, illumunates about 5 minutes after the car is started).

Hmmm... We take the old compressor, and apply 12vdc to it. The compressor chugs right along. We pull the new compressor out, apply 12vdc to it. Likewise, it chugs right along. Put the old compressor back in, apply 12vdc to it manually, and it pumps up the air shocks, no problem at all.

Ok, now what? My buddy pulls down some info off the web (alldata?), and we see there is a relay that controls the air pump. I don't know anyone else with the air suspension that I can swap the relay with, but it seems reasonable that the relay is toast. So I go back to the dealer and buy a relay. OUCH! $120! For a damn relay! But hey, I figure I'm still $300 ahead of the game from what the dealer wanted to replace the "defective" compressor which clearly wasn't defective.

I swap the relay on the truck, and it has no effect. Of course, the dealer won't do a refund since it is an "electrical" part and there are no returns/refunds on electrical components. What's the likelihood that I have a defective relay from the dealer? Very small, so I doubt that is it.

We did all of this work yesterday. I'm out of ideas now. We were able to manually pump up the air shocks by applying 12vdc to the compressor when the truck was running, so for the time being everything is pumped up and driveable.

But... What else could be causing the air suspension not to work? I'm baffled. Its not the ride height sensors, those clearly work since they pumped up when we "turned on" the compressor manually. It wasn't the relay. It isn't the compressor.

All that is left seems to be the Air Suspension computer, and I can just *imagine* what that costs.

All the wiring looks like it is in good condition. Is there a way to troubleshoot the wiring to see if I'm getting 12vdc to turn on when it is supposed to?

Does anyone have any ideas? I'm really hesitant to go back to the dealer, since they told me the wrong thing to start with.

Thank you,
Vinny

Is the ass end of the truck sitting low? When you jump power to the compressor and it runs, you said it'll raise the rear end up...does it stay up? Does it leak down if you let it sit for a while?

The ass end does get low, but it takes a long time for it to happen (week+)

Check the air line union near the air filter box; it's prone to cracking/leaking, often times ultimately they break, flattening the suspension in a hurry. If the suspension module doesn't sense the rear raising when the compressor is running (because of the broken/leaking union), it'll minimize compressor run time or won't run the compressor at all as to not damage it. The union itself is like $10 or so. I wish I had a picture to describe, just peak around the air filter box and master cylinder area, it'll look almost like an electrical butt connector, black, with two air lines going to it on either end.

I'll check in the AM when I can see better. However, if this connection were broken, wouldn't the air suspension at least kick on initially when the truck is turned on? The reason I ask is even when the ass end is low, when I start the truck, the compressor doesn't kick on at all. Its as if it isn't getting any juice (which made us suspect the relay). From your description I would expect it to at least kick on for a few seconds and then perhaps shut off.

Vin

If I found the piece I think you're describing, it's perfectly intact and doesn't appear cracked.

This morning, I popped the hood while my wife was in the truck. I had her start the truck, put it in N, and then switch to 4WD LO. It is my understanding that this is supposed to tell the air suspension to pump up to its highest level. The air pump never turned on, not when she started the truck nor when she changed to 4LO.

I suspect an electrical problem or a problem with the air suspension computer. What else could it be?

Have you tried the relay test I mentioned in the other thread?

Or look to see if the switch is "off"?

Hm...all the doors shut? No errant door ajar lights or anything like that?

I'd hate to tell you that it's a module, then you run out and throw a module on it and we're back in the same boat we started off in.

Yes, all the doors shut. No errant door ajar lights. Everything you would expect to be in place for it to work. The switch isn't off (normally if the switch is off the Check Suspension light immediately lites up when you start the truck... whereas in this case, I don't get the light until about 5 minutes into the process).

In the other thread when you said "apply 12vdc to the two large wires". Do you mean complete a circuit between the two a-la 12vdc to 1 wire and the other wire to ground? Or literally apply 12vdc to BOTH wires? I meant to ask that. I got home too late tonite to do anything anyway.

What's a module? Do you mean the suspension computer? I'm hopeful its something easier like a loose connection :)

Thanks,
Vin

just take it to the dealers man, get your headaches out of the way with this one. Let the dealer figure it out! :rolleyes:

Err... If you actually took the time to read my initial post, you would have seen that I *already* took it to the dealer, and the dealer's diagnosis was *wrong*.

So, what are you suggesting? That I take it to the dealer, let them charge me $625 to put in a replacement component I do not need, and *THEN* tell me "oh, you also needed a <insert name of the actual part that was broken here> which cost another $400"?

dealers LOVE people like Mountain...boy above. :lol:

Yes, complete the circuit on the relay with 12volts. The same way you did it with the compressor when you tested it.

If the relay is good, compressor is good, then your problem most likely lies in the LLS computer (module). The union talked about above will not give you the problems you are having, but it would be a good idea to replace it with the new style union or just get one and keep in the glove box.

Good luck.

Oh, if you do have to replace the computer, look at places other than the dealer. Go to places like Fordpartsonline, Strutmasters, etc. You can probably get the computer for 1/2 of what the dealer will charge you.

Thanks. Another person here sent me a couple of scanned pages from the Helm Vac & Electrical manuals which show a diagram of the LLS circuit. I think I understand it.

It appears that the solid state relay has 4 connectors - A B C D.

A is labeled as being connected to the power distribution box, always hot, on fuse #15, a 50 amp fuse. I can disconnect the relay and see if I have 12vdc on terminal A. If I do not, perhaps there is a problem w/ the wiring back to the distribution box or the fuse, where honestly I didn't think to look before). I can check continuity if I don't have 12vdc and see if there is a break in the wiring.

B is labeled as being 12vdc from the relay to the air compressor. Here, I can test continuity of the wiring from the relay to the compressor to make sure I don't have a wiring problem. Since B is switched by the relay it normally wouldn't be on unless their LLS computer says to switch it on.

C is labelled as a ground. I can test continuity here to ground on the chassis. If I have a bad ground, naturally the pump wouldn't turn on. Oddly enough, the diagram shows that the ground wire from the air compressor itself splices into this same line before it goes to ground, so I can eliminate two potential wiring problems at the same time.

Finally, D is labelled as 12vdc connected to the Air Suspension Module. I assume D is not normally energized unless the computer wants to pump up the system. So, this connector will normally be 0vdc unless the air suspension pump is being turned on. This line terminals at the 4WAS module, pin 18, so again with a little ingenuity I should be able to test continuity to make sure the wiring is secure.

If the wiring is secure, and I don't get 12vdc output on pin D when the LLS should engage the pump, I think its safe to conclude that the 4WAS module is toast, yes?

Does all this sound reasonable? I'm going to take a 1/2 day out of work tommorrow to try and fix it while there is still daylight.

Thanks for the tips on web sites too if I need to order another module. Is there a part # I should reference? The documentation another member sent to me doesn't show a part # for the 4WAS module.

Thanks again
Vinny

Here is a thread from another site the might help you a BUNCH on this. It will also give you additional info we have not discussed here. Read this before you start on this project.

http://www.ford-trucks.com/forums/sh...ght=lls+wiring

Thanks for the link! Interesting reading!

The 12vdc vs 7vdc across pins C and D of the relay is interesting. The scan of the HELM manual, page 41-1, clearly shows a little "12v" next to Pin D, while Pin C shunts to ground. Its interesting that others would measure 7vdc rather than 12.. The resistance reading on Pins C and D will be helpful too, although like I said before I doubt the relay itself is bad since it is brand new (although it isn't unheard of).

Although..the dude was getting 7vdc across pins C/D and his pump *wasn't* engaging, which would seem to imply that 7v is insufficient voltage to trip the relay. 7v may always be present until the module wants to activate the pump, and then it goes up to 12.

The ride height in the front and back both appear to be fine, especially once the system pumps up. It doesn't look like the front changes all that much, though, I honestly don't think its ever moved once that I can recall.

I guess what I'll do today is test the relay per my previous post, and then if that seems to accomplish nothing I can pick up another ride height sensor and try swapping it. Of course, I'd hate to buy a new one of those to and have it (again) not be the solution. Any ideas how to test a ride height sensor's operation?

Not sure how to test the RH sensors. Not sure if you can. The thing with the 7v vs. the 12v has me concerned also. I am not sure what it really is supposed to be. Most computers do not provide 12vdc output, and with the relay having a dedicated 12vdc source, it makes sense to me that the output from the computer would be between 5-7v. All that signal is going to do is "open / close" (can not remember if these relays are Normally Open or Closed contacts) the relay contact, thus completing the 12v power to the compressor. :confused:

If I remember, I will check and see what voltage I get on the smaller wires when I get home and will post back here with the info.

I would not count out the sensors yet. They provide a signal to the LLs module as to when to raise / stop / lower the system. You can have a bad sensor and still raise the vehicle by manually providing power to the compressor, thus bypassing the module. Let me ask, when you manually raised the vehicle by powering the compressor, did it stop on its own when it got to height or did you have to stop it by removing the power source?

Bummer. Would hate to buy one only to find out that isn't what is causing the problem.

I agree. However, the HELM manual seems to imply that there is 12v going to the module. For example, on page 14-1 it soes that Fuse 4/15amp comin out of the power distribution box goes to the Air Suspension Service Switch. That switch either shunts to nowhere (if turned "off", breaking the circuit) or (if ON) completes the circuit into pins 1 and 21 on the Air Suspension Module. Furthermore, Pin 4 is shown as coming thru the fuse/relay panel into pin 4, and is only hot @ 12v (run) which means when the truck is running.

Thus, it isn't out of the realm of possibility that the module can supply a 12v signal to a relay. That same page shows a switch on pin 18 which shunts to ground. My assumption is the switch is closed (no voltage) when the computer doesn't want to run the compressor, and opens (proving voltage) when it does, to trip the relay.

Thanks, that would be helpful and would supportwhat I should expect to see when I go home in an hour.

I've never seen the front of the truck change height, only the rear. The front appears to be fully inflated. I assume I have a small leak in the rear which causes the truck to lower over the course of a week. If I pump it manually, it appears to stop "at height", although I also couldn't say with any certainty I know what "at height" is really supposed to be.

Regards,
Vinny

Put an ohm meter across the ride height sensor and move it throughout it's travel, see if the resistance varies as the travel of the sensor changes.

Problem solved!

The problem was with the relay connector.

Apparently, the 'A' wire totally corroded inside the connector and disintegrated. I discovered this when I tested for 12vdc on the A pin. no voltage.

There's a little "cap" on the connector. I popped the cap off, and pulled on each wire. The A wire came right out! It was severely corroded.

By the time I figured this out, it was well after 12 when the parts dept at my dealership closed. So I picked up a few "crimp" blade connectors at the auto parts store, removed the old connector, and then put on 4 crimp connectors.

I reconnected the 4 crimp connectors. Eureka! The air suspension works again!

Total time to fix: 1 hour

No other connector showed signs of significant deterioration (B showed a little but not much). I guess the high current coupled with the poor position of the relay means it picks up a lot of road salt and eventually oxidizes.

Thanks everyone for your help! this forum is great!

Oh, and as it turns out, I didn't need the relay either. My old relay was okay. My old compressor is ok. I can resell the compressor on Ebay and make my money back.

Again, thanks everyone for saving me $625 at the Stealership. Amazing they would have charged me for a compressor and probably charged me for the wiring harness too saying I needed both!

I'm glad I didn't listen to that other dude who said go back to the dealership!

My out-of-pocket expense: $75 diagnostic fee at the dealership (waste of money) $120 for the relay (which turns out I didn't need), $4 for the crimp connectors, $0 for the replacement compressor (I figure the compressor I can sell for what I paid, so that'll be a wash or maybe I might "lose" $20 on the deal) --- $229 total

Actual cost to repair had I come to this forum first: $4

Savings thanks to everyone here: Priceless


I wonder if I can dispute the $75 diagnostic fee on my credit card ;)

:rocker:

Now, Q. Did you by chance test the voltage across the connections coming from the module? I got home too late last might to test mine and was gone all day today. Just wondering, that way we can put the 12v vs 5~7v thing to rest.

:beers:

I wish I would Have seen this thread sooner, as I know a guy who sells all the stuff dirt cheap and is highly educated on how it works and will always help his customers until they find the issue. For future reference of those who experience these types of problems, the link is

http://www.americanairsuspension.com

and he has a great deal on all the parts at

http://www.americanairsuspension.com/1-2-1-deal.htm

OK - I am having the same problem as Tentpig did. (99 Navigator) My question is - is this relay and connector setup located directly under the air-box? I think that is what I am looking for. I also could not identify the air union described near the master cylinder. Does anyone have a picture? I would rather take the engine completely out rather take my Navigator to the dealer!
Any help is greatly appreciated.
KS

Here is a diagram, its kinda crappy but the only one I can find on alldata

http://i10.photobucket.com/albums/a1...99x/airsus.gif
http://i10.photobucket.com/albums/a1...9x/airsus1.gif
http://i10.photobucket.com/albums/a1...9x/airsus2.gif

I now have the same problem. My check suspension light is on. My air compressor works, I disconnected the wire to the relay and hard wired Pin A and Pin B and the compressor worked.
When the compressor works both the front and the rear is lifted so my front is very high and my rear is just about right.

Hey guys, where is the relay? the module?

ok. yesterday i got a new relay from Ford and my suspension is back to normal now :rocker: . The relay is behind the front bumber on the driver side. I found mine just close to the horns.

Also the new relay I got from ford has a different part number already than the original. Guy from the dealer says its normal for Ford to change part numbers.

Some information I noticed regarding the relay.

1. Both the new and broken relay I got I can't measure the resistance from pins C and D.

2. When my Check Suspension light is "ON" the voltage I'm getting from pins "C" and "D" is 3.2 volts.

3. I checked the relay by applying 7 volts to pins "C" and "D" and check if pins "A" and "B" closes. If it does then the relay is working if it is not then it's broken.

Workaround I did:
My LLS broke on Dec. 24 so no Dealers where open and I can't get the relay until Dec 29 and I needed my gator working because its the holiday season and we have a lot of relatives visiting us. What I did is to remove the relay, buy a 3-4 meter wire put a switch in on end, on the other end connected to wires which was connected to pin A and B (thick wires) of the relay. I ran the wires into the drivers seat so I can manually turn on/off the switch for the air compressor :lol: I acting both as the driver and the air compressor relay :lol: Be careful not to overinflate though.

The module is inside the dash.

More info on diagnostics regarding relay voltage.
 

Problem I had --> Front Sensor bad
Symptons --> Check suspension light, no air compressor sound.

Actions taken --> Read this forum. Tested relay but became confused and wound up replaceing relay.

Observations --> Pin C and D voltages ( before front height sensor replaced and problem solved )
1. key on = 7.5 volts ( with the bad sensor)
2. air switch by passenger off = 12 volts.
3. After replacing height sensor and turning on switch 12 volts. Air compressor pumps.

A measurement of less than 12 volts between CD must mean the computer is in a "wait state" looking for data from the height sensor.

Hi, this thread has been very helpful to me. So, here's my situation (I share as others may be in the same pickle). I have a new-to-me 1998 Navigator, 5.4L, all factory, with air suspension.

Initially, my compressor never comes on and the rear is sitting awfully low (makes for a horribly bouncy ride). So, following the thread I hooked up a by-pass for the compressor; when I apply 12V battery voltage to the compressor (key in ignition, ignition turned to start (but not actually running), doors closed, then the compressor comes on and the front would pump up, but not the rear.

Following air lines, I found the union (under the master cylinder) had blown: Bought an air line union from NAPA (3/16", metal, $8), cut new ends to the air lines, stripped about 1/2" of the black from each end of the air lines, plugged the white ends into the new union, and now I have air going to the rear. Manually pump it up again, but after a few hours, the rear is sitting low again.

More reading and research led me to the following: Using the by-pass procedure, I pump up the front and the rear ends manually. Then I turned the air suspension system OFF, using the on/off switch in the passenger leg room area. 4 hours later, my passenger side is still inflated, but the driver's side is sitting low. So, now I know that there is an air leak and it's located in the rear driver side.

I mixed up a spray bottle of soapy water (joy and water), crawled under the rear driver side of my Navigator, and started spraying the air shock and solenoid of the air shock. For me, it was instantly obvious that the leak is in the area of my solenoid.

Now for my question: I see there are rebuilt solenoids and rebuild kits for solenoids on the web. But how do you actually remove/install the solenoid. There must be something holding it in location or the air pressure would pop it out.

I've looked and looked on the web, and the only thing I can find is talk about some retaining clip and twisting the solenoid (to release air) and twisting again to remove. Rather vague stuff. Does anyone have a picture of the retaining clip? And twist how (clockwise, counterclockwise, no difference)? Thanks in advance.

I don't even want to address the problem of why the air suspension isn't working automatically yet, I just want it to hold air when I manually pump it up (for now -- actually, I think the failure of the auto-suspension is a blessing in disguise; otherwise, with such a large air leak, the compressor would run excessively and eventually burn itself out).

What I'm thinking is why u didn't get the Monroe LLs-standard suspention conversion kit for 230$ and less if u look right and no more guessing what's wrong with your truck

go to strutmasters.com and get a conversion kit

You're absolutely right
 

T5.4

You are absolutely correct. In fact, through AdvanceAuto, I purchased the Monroe conversion kit ($200 after internet discount) and about 3 hours work, and I replaced my back air bags with springs.

The airbags remove easy enough, and with a spring compressor, I was able to compress the coils so I could install them without removing the shocks (the dang bolts on the shocks are rusted solid, so removing the shocks would have been a big pain in the neck).

Anyway, long story short: Remove the stinking air bags and replace them with coils. Rides nice now, even when towing my 21' wellcraft.

where exactly is the relay located....