Suspension dropped while in traffic

[powershift]

While stopped in traffic, the front end on my 2012 dropped down. I pulled over as soon as I could, got out to inspect the ride height and found it to be level/slight rake. I'm 100% certain it dropped in the front. No codes or messages on the DIC. Any ideas on what happened that caused the front to drop and then slowly raise back up? I was quite nervous since I didn't want to break down on Las Vegas Blvd. This is what it looked like afterwards:

 

[jlglr4]

Mine will try to self-level if it is stopped long enough (few minutes) and on a slight incline, though I’m not sure if it will do that when in drive rather than park/neutral. I don’t see any detectable sag in that photo.

 

[16FujiDisco]

Mine will do something similar most noticeably at a drive through; almost like it’s going into access height. It is a quicker deflate than usual, and I wondered what it was the first few times.

 

[Nechaken]

Are you sure it dropped then raised back up? It may have been the front dropping (points down) then the rear dropping in succession (making you level again). I've had 2 LR4s and they both do that once in a while when stopped at a long light. I believe that, as long as you're not in tight tolerance mode, the system will only adjust when it is more than 10mm off the commanded position.

So, maybe last time you parked the ground wasn't level or you were carrying fewer or more passengers. Or perhaps temperature changes modify bag pressure. After it collects enough data and the car comes to a stop (ride height sensors won't have fluctuating values) it makes a quick adjustment.

 

[mm3846]

Mine does this a lot. I feel like it happens at certain intersections.

 

[powershift]

It sounds normal, as I get used to the LR4 I'll try not to let my heart sink next time it happens lol. This morning on startup the front raised about 1/2" to 1". Is that normal too?

 

[f1racer328]

It sounds normal, as I get used to the LR4 I'll try not to let my heart sink next time it happens lol. This morning on startup the front raised about 1/2" to 1". Is that normal too?

If the front sags overnight it will raise back when you start the engine.

Your front valve block might be leaking or the air struts could also be leaking.

There’s a fuse you can pull, let the car sit overnight, and check the results in the morning.

Measure the suspension height right after you pull the air suspension fuse, and let’s say 12 hours later.

 

[Longtrail]

Do the overnight test as mentioned by f1racer328; leave it longer if you can; that will confirm if there's a leak. I suspect however, as others have pointed out that this is just a levelling adjustment and you don't need to worry. There's no other reason for these to drop unless there's some big failure in which case you'd probably hear the compressor (situated in front of the driver side (US driver) rear wheel) working overtime to achieve the desired ride height...

"It sounds normal, as I get used to the LR4 I'll try not to let my heart sink next time it happens lol. This morning on startup the front raised about 1/2" to 1". Is that normal too?"

Does suggest you have a slight leak, park it on level ground when you do the overnight test and pull the fuse (I don't recall which one but it's under the hood on the passenger side and is well documented on this site), there are plenty of YouTube videos that document the procedure. I had this issue, once I fitted new o'rings to the front, center and rear valves the vehicle no longer sags.

 

[f1racer328]

The desiccant in part of the air compressor assembly tends to break down and start going through the airlines, then getting on the O rings of the valve blocks, causing a leak.

My car noticeably sagged after sitting for 4 days or so, so I took apart my front valve block and just cleaned it. Hasn't sagged since. Didn't even replace any parts. I do however need to replace the desiccant material eventually.

 

[bdd123]

Are you sure it dropped then raised back up? It may have been the front dropping (points down) then the rear dropping in succession (making you level again). I've had 2 LR4s and they both do that once in a while when stopped at a long light. I believe that, as long as you're not in tight tolerance mode, the system will only adjust when it is more than 10mm off the commanded position.

So, maybe last time you parked the ground wasn't level or you were carrying fewer or more passengers. Or perhaps temperature changes modify bag pressure. After it collects enough data and the car comes to a stop (ride height sensors won't have fluctuating values) it makes a quick adjustment.

What is tight tolerance mode?