I own an 04' Expy with the 4-corner load leveling suspension. I despise this feature, but when I turn it off, the vehicle does not sit or drive as high as it should. The message really gets on my nerves also. Is there any way to disable the message and have the ride height where it should be?The compressor comes on after the vehicle has been sitting off in the garage for hours and just riding along the highway. The dealer said it shouldn't happen, but is not a problem

 

From the sounds of it, its running just fine, like it should. If you do not like it, you might look into a spring conversion kit for it. Strutmasters.com sells conversion kits.

Here, http://www.strutmasters.com/catalog.php?cat=52 $500 and you can kiss the LLS goodbye.

 

I feel the same way. I hate that my Navi lowers when you park it - and then the damn compressor has to run for over a minute to get it back up. It draws a ton of current too - probably cuts into your battery/alternator life having a heavy load for 60+ seconds every time you start your truck.

The worst is when a bunch of us go to lunch (1000+ lbs on board). After it lowers during parking, we get back in and it takes at least 120 seconds of compressor on time to get it back up.

I have the shop manual and it says that with the air susp switch "off" the system is only active over 15mph. If you think about it - that is exactly what we want! No bleeding off air when parked - but still will do load leveling in regular driving. Unfortunately - I believe the shop manual to be wrong - as I am pretty sure my compressor will not come on at all with the switch off.

I have had a Lincoln Mark VIII for a long time so I am very used to air suspensions. I like it on the car, but it only has to run for about 10-15 seconds on the car! Navi has the SAME compressor and much more air volume to work.

You may want to try driving with you switch off, and get up to about 20mph and hold it, and see if you can hear that annoying compressor kick on (this would only work if the truck had lowered last time you parked it). I'm curious to see if your will work the way the shop manual says it does.

There are solutions to this problem. Unfortunately, this is a computer-controlled function (this is separate from the main EEC-V one) and the best fix would be one where that module was "reflashed" with modified software (not gunna happen).

One thing I thought of was an electronic switch where (something as simple as an "and gate") where for the module to work it would need a signal from the ignition position switch saying "were in run" AND the normal input (we could use pin 25 on the 4WAS module which is the input from the service switch). This would only require one TTL chip (which are almost free), a 5VDC regulated power input (use pin 17 or 8 on the 4WAS module), a ground (pin 20 or 19 look good), and the two previously mentioned signals. The only thing not available right at the module is the ignition key position input (I'll have to look into that more).

Anyway, I'm just thinking out loud. Let me know how your 20mph test goes.

 

From the Ford shop manual (regarding the air susp service switch)......

"........Without the module receiving this signal, the 4WAS system is inoperative at speeds below 15 mph and will not react..........At speeds above 15 mph, the system will be active as if the air suspension service switch is in the ON position"

Sounds like what we want. I'll check mine next time I drive it.

 

Where is this switch located? I have an 04 Ultimate 4x4, and have "never" experienced lowering, or a compressor sound.

 

On the Navi it is the drivers side rear cargo area behind a cover about 8"X6" big.

The truck lowers 1" when you exit the vehicle and close the last door. It then raises back up to trim height (so about 1") when you get back in, close all the doors, start up and drive away (takes 60-120 seconds to get back up that 1"). What we are talking about is electronically disabling the kneel feature which will do a few positive things:

1. Help extend battery/alternator life by not having a 30-35 amp draw for 60+ seconds every time you start the truck

2. Less NVH from the compressor (as it wont be running anywhere near as much

3. greatly extended compressor life expectancy (like take it from maybe 7-8 years to 13-15 years)

4. Slightly better treadlife out of all 4 tires. This is due to the greater amount of negative camber (remember we have independent suspensions = more negative camber when lower) when the vehicle is driven those first 2 minutes (especially when you normally drive with 4+ people). With kneel disabled - your camber all around will be much closer to zero when everybody hops in to go somewhere else. This will impact those who take lots of short trips every day the most.

In a full-size SUV I think the kneel feature is pretty useless unless your pretty old with arthritis and have trouble getting in the truck. If I had designed the system, I would have made it selectable on/off through the message center just like lots of other functions are.

I did verify that the system does NOT work as advertised in my 2003. The system isn't throwing any 4WAS codes (I have the autoenginuity software package which lets me view pretty much all of the vehicles electronic stuff). So the bottom line is the system is disabled at all speeds with the switch off.

I'm gunna disable the feature with a TTL chip and use the "key in run/start" signal (which is available to the EEC) as the discriminator. That way - everything will work normally when the truck is started and running, but it will be like I flipped the off switch at the instant the key is rotated into "off". There will be no "air susp off" message as the truck only displays this when the key is in run/start - at which time the 4WAS system will be operating normally. I'll post some pics afterwards of how I do it. It will be a few weeks as I have some bigger fish to fry (non car related).

 

Thanks for taking the time to respond.

So... If the switch is off, I should leave it off?

 

No your better off leaving it ON. If it was off, you would get a message that said air suspension off. Yours is probably on, you just havent noticed the small amount of "lowering" when it kneels.

Plus the 04's have a new compressor bracket that is a bit quieter.

 

If your system is taking the amount of time you say to raise back to position, then there is something wrong.

IIRC, it should take no longer than 20sec to raise the truck from complete deflation, according to Ford. Might want to get that looked at, or investigate it further.

I know when I leave my truck un-driven for a few days the system will completely deflate (yes I know, it has a leak in cold weather, it does not do it in hot or warm weather, so I hve yet to bother with it), yet it only takes it 10-15 seconds to completely re-inflate the bags.

 

I can't speak to the pre-2003 navi/expo's with air susp, but the 03-04's do take that long to go from "kneel" to ride height. Maybe the older ones do not kneel, explaining why they are good in 15-20 seconds.

The kneel is a 1" drop all around, so it must overcome that + the weight of however many people just hopped back in.

I still like the versatility of the air susp. you can lower or raise the vehicle (over about a 3-4" range) for free by manipulating the sensors. So if you like the off road look, you can manipulate the system so that it stays in its 4X4 low height, or if you have a 2WD you can keep it in the kneel height all the time for more of a lowered look (if you like that sort of thing). If you were going to mess with the system to achieve one of these two heights full time you should definitely get the truck aligned at the height you plan on using it at to get that camber right.

 

Mine also "kneels" (99 expy). When it "kneels" it only takes ~5sec to raise back up. I'm just trying to tell you, that the system should not take 60sec or longer to rise 1", much less that amount of time to rise from full deflation on the bump stops.

 

huh, I guess I need to take a more critical look at it, and compare it to another 03-04 at a dealership (to see if mine is taking an unreasonable amount of time to pump up). I still plan on doing the little work around once work settles down a bit.

 

What is this talk of manipulation....you know...for a higher ride? How do I accomplish this?

 

You can move the ride height sensors up or down to adjust the ride height. But, be aware that the adjustment is not proportional, so you will have to "play" with it a bit to see what does what. On mine, IIRC moving the RHS 1/4" moved the truck up ~1". Take caution in moving it too much either direction.

 

IIRC? The RHS is the sensor. correct? The cylindrical do-hickey above the axle?

Most of this is for information only. But I really appreciate your feedback. I have most of the vehicle systems down pretty good but this LLS just escapes me.