H2 air suspension

[The_Mountain]

A month or so ago (just before the great forum hack), I had taken my truck in to have the trans checked. While the tech had his scan tool plugged in, it found a code in the air suspension. The message was something about loss of communication between the BCM and the air suspension. I asked here on the board if anyone knew what the BCM talked to, and if there was a "usual suspect" I could look for i.e. if the problem was usually caused by a particular cable coming loose, or if there was a specific sensor that typically caused this problem. Also, if not, was it worth crawling around under the truck looking for loose connections.

It looks like the suspension isn't leaking, so far as I can tell. Does anyone know what the normal pressure is supposed to be? The readout was 43lb according to the tool. Also, my left rear corner sits a bit low, and the sensor reading is 2.2v, whereas the right side sensor is more like 2.6v. I didn't get a chance to see if those are the voltages the system is expecting, or if the left-rear is out of spec but the system can't correct it. I'm going to try to see if the mechanic there will let me buy time with that tool to see if I can force the suspension to level out. I messaged the guy someone suggested I contact here on the board, but it looks like the forum reset wiped that out, so if someone could re-suggest the name of the member who is supposed to be knowledgeable about the air suspension, I'd appreciate it.

 

[USMC_315]

I'm going to give you the most helpful advice for this/your situation...


PURCHASE A SPRING OVER CONVERSION

I used to have an H2 with the air suspension and it was a money pit (the suspension). You will waste stupid amounts of money trying to fix and keep that air suspension system alive. Save yourself the time, money, sweat, head ache, and supplies by just getting springs and taking out those stupid things. Unless you truly need them, which I highly doubt you do, get the springs that will ride just as nicely and never force you to maintain them (or make you look like Pedro's cousins rolling up in a '71 Grand Ville (yes, I looked it up just for this post)).

 

[The_Mountain]

I'm going to give you the most helpful advice for this/your situation...


PURCHASE A SPRING OVER CONVERSION

I used to have an H2 with the air suspension and it was a money pit (the suspension). You will waste stupid amounts of money trying to fix and keep that air suspension system alive. Save yourself the time, money, sweat, head ache, and supplies by just getting springs and taking out those stupid things. Unless you truly need them, which I highly doubt you do, get the springs that will ride just as nicely and never force you to maintain them (or make you look like Pedro's cousins rolling up in a '71 Grand Ville (yes, I looked it up just for this post)).

Granted that in the long run, the conversion is much less of a headache. And that's the plan if this gets at all expensive. Right now, I'm fairly confident that all I've got is maybe a dead or dying sensor, or a loose wire. The springs themselves aren't leaking, and the compressor seems to be operating correctly. My plan of attack is to first see if just changing the voltage value for that one height sensor causes the suspension to level itself. If that doesn't do the trick, then I'll see if there's a bad connection or maybe the height sensor itself is failing (a $35 part, I believe). If none of that solves the problem, then I'll start considering the spring swap. Ditto if the compressor itself goes south, or I actually lose an air bag. It's just that right now, there are a few other major repairs I need to take care of first e.g. the entire exhaust system needs to be replaced from the headers back (left side manifold is leaking, both cat downpipes have holes/rust, and the "replaceable" system from the cats back is also rusty and holey), the trans is almost certainly on its last legs (though luckily that's covered under the warranty I bought), the sunroof rattles (loose linkages), my rear-passenger window regulator mechanism broke (another warranty fix), and I'm going to need new tires soon. Since the issue I'm having with the air suspension is more of a "nice-to-have" right now, I'm willing to look at these minor fixes to try to correct the lopsided suspension angle.

The thing about converting to a coil suspension is: how much of the air suspension system can I then remove? Is there a way to tell the BCM that it doesn't have that system? Can I get rid of the height sensors, the compressor and related wiring?

 

[USMC_315]

The thing about converting to a coil suspension is: how much of the air suspension system can I then remove? Is there a way to tell the BCM that it doesn't have that system? Can I get rid of the height sensors, the compressor and related wiring?

If I remember correctly, all I did was just take out the air bags and then replace with springs. I'm pretty sure the sensors will just look at it as if it were riding in the normal mode. Not 100% its been quite some time

 

[twinmill28]

I think in the older H2's the air suspension has given people more fits but in our '07 we got the upgraded compressor and have only had to change the bags once in 75K miles.

Ours is a dedicated tow rig so switching to coils is a non-player; the bags make trailer towing way smooth and worth the effort to keep the system working.

I've heard that you will get the DIC warning until you trick the system into believing the bags are still there. Rock Auto sells coil springs with the pieces needed for the electric portion.

 

[Renagade132]

If you disconnect the power to the air compressor, it will get rid of the "service air system" warning that will come up every time or every other time you start the truck, because if the compressor is not disconnected, it will turn on an shut down after a moment, I guess it's assuming thier is a leak in the air shocks, even though they are not there anymore, until fully disconnected. Yes I want through this my rig.

 

[The_Mountain]

Air suspension-related question: Why would the "lean" be getting worse, yet the bag is obviously not leaking, since the compressor isn't running constantly, and it sits at the same angle after driving for some time?

 

[twinmill28]

My bags were shot but it took quite awhile for it to show. The truck dropped completely once or twice over the course of about 8 months but held tight otherwise. The compressor didn't run all the time but I'd occasionally get an air suspension message in the dash. Then finally one day the truck dropped and didn't come back up.
When I pulled the bags they were completely dryed out and dry rot cracked horribly. I couldn't believe they took so long to die. Replacement was quick and easy, almost no tools needed other than something to loosen the plastic fittings on the lines at the bag. Once the new ones went in things have been great for quite awhile now.

 

[KTM640Dakar]

Rear spring kit is $100.

 

[The_Mountain]

Well, the compressor is running a lot more often now. At least every time I start the truck, and for longer than it used to. When I first got the truck, the compressor would run when I first started in the morning and run for maybe 10-15sec, but not during the day unless I had been on the highway. Now it runs for 20-25sec in the morning, and just about every time I start the truck during the day. It doesn't (yet) sit lower, or sink down, but I think it's time to convert to coils.

KTM640Dakar, where are you seeing the rear spring kit for $100? The cheapest I've ever found is about $150.

Also, general question: What tools are needed to do the swap? As I understand it, the various components that the airbags attach to and ride on have to be removed. I (unfortunately) don't have access to my socket set anymore, so I'll need to swing by Harbor Freight to buy the specific wrench(es) needed, so if someone here knows specifically what is needed to remove the various suspension bits, please let me know so I can get everything lined up before I start disassembling. I don't want to get halfway through this process only to discover I don't have a particular tool, since I don't have a second vehicle available to do parts/tool runs. I'm looking at the Touring Tech kit, which claims to fit with no adapters necessary. Will I need a set of spring compressors to get the coils in?

 

[The_Mountain]

Well, I'm gonna take the truck in to a local shop sometime this week to get an estimate for 4 shocks and swapping in coils (Touring Tech). I could probably do the work myself in the driveway, but the weather here is gonna be lousy for the next week and a half at least, plus I'm going to be without the truck for at least a few days while I get the transmission redone, and I need to have everything sorted before mid-Feb. I've decided to go with the KYBs, mainly for the price. The Bilsteins sound great, but I don't have that much free cash right now. To compensate for the KYB's alleged stiffness, I'm gonna find a good washed-out road somewhere around here, and really work the suspension for a bit to see if that breaks them in at all.

 

[The_Mountain]

Update: my new Touring Tech springs showed up today, along with the Moog noise isolator bushings. The springs are indeed different heights, and it's quite easy to see which end of the coils is more tightly wrapped. so it's no problem determining which end is "up" and which spring goes on which side of the truck. The KYB rear shocks should be here in a day or so, and the fronts by the end of next week. The springs did come with instructions, and although the paper got a bit torn up from being in the box with the springs, it's still quite readable. Only the picture was damaged, and all it shows is the location of the suspension relay in the front left fenderwell. The text is very clear. There's a local shop that will do the spring install. I showed them the video from the Strutmasters install, which shows the process of getting the rear springs out, and they agreed that it shouldn't take more than an hour. I'll take care of the electrical side of things myself. If anyone has suggestions for the best method of sealing off the exposed plugs for the relay and the compressor harness, I'd appreciate any input. For the relay, I'm seriously considering gutting the relay body and clipping it back on as a cap to the plug. At least that way nothing will get in. The compressor plug will be harder. Both connections are on the underside near the wheels, so there's bound to be a lot of mud and water contamination if I can't get them closed off properly.

Once the shocks get here, I'll open them up as well to make sure all the hardware is present, and that everything goes together properly. According to one comment on Amazon, the fronts might not have the bushings to properly hold the shock in place? So I want to examine them in particular to see if I can see how they are supposed to be mounted. Also, the KYBs are apparently special in some way, and require that they use their own bolts etc, and the stock parts don't fit correctly.

 

[twinmill28]

Now I know how an environmentalist feels when a tree gets cut down.............:gaah:

 

[clubhunt]

Update: my new Touring Tech springs showed up today, along with the Moog noise isolator bushings. The springs are indeed different heights, and it's quite easy to see which end of the coils is more tightly wrapped. so it's no problem determining which end is "up" and which spring goes on which side of the truck. The KYB rear shocks should be here in a day or so, and the fronts by the end of next week. The springs did come with instructions, and although the paper got a bit torn up from being in the box with the springs, it's still quite readable. Only the picture was damaged, and all it shows is the location of the suspension relay in the front left fenderwell. The text is very clear. There's a local shop that will do the spring install. I showed them the video from the Strutmasters install, which shows the process of getting the rear springs out, and they agreed that it shouldn't take more than an hour. I'll take care of the electrical side of things myself. If anyone has suggestions for the best method of sealing off the exposed plugs for the relay and the compressor harness, I'd appreciate any input. For the relay, I'm seriously considering gutting the relay body and clipping it back on as a cap to the plug. At least that way nothing will get in. The compressor plug will be harder. Both connections are on the underside near the wheels, so there's bound to be a lot of mud and water contamination if I can't get them closed off properly.

Once the shocks get here, I'll open them up as well to make sure all the hardware is present, and that everything goes together properly. According to one comment on Amazon, the fronts might not have the bushings to properly hold the shock in place? So I want to examine them in particular to see if I can see how they are supposed to be mounted. Also, the KYBs are apparently special in some way, and require that they use their own bolts etc, and the stock parts don't fit correctly.

Heat Shrink Heavy Duty End Caps

 

[The_Mountain]

Now I know how an environmentalist feels when a tree gets cut down.............:gaah:

Why do you say that?

Heat Shrink Heavy Duty End Caps

Got a link, or a source?

 

[clubhunt]

http://www.electriduct.com/Heat-Shrink-End-Caps.html

 

[twinmill28]

Thanks for the link on these caps clubhunt! I thought I was doing great using Del City for all my auto electrical needs, but they don't have these. I wrapped up a project that I needed the caps for and instead used the glue lined heat shrink and pressed the end together to seal it--this is a much neater way to do it.

 

[The_Mountain]

OK, it's done. The new Monomax shocks ride pretty nice, as far as I can tell. I was expecting them to be harsh, but they seem quite compliant. The new springs went in smoothly. The bags I pulled out were actually in pretty good shape. I didn't see any cracking or rot at all. I guess the suspension lean was entirely a sensor/computer problem. In any event, I got the harness unplugged from the compressor and the relay with only a little wrestling. The new springs and noise insulators fit great. I kept the air spring perches just in case. We had to snip the air lines because we didn't have a way to deflate the system (or at least I couldn't find one). I'll get under there later today and try to cover the various plugs with something until I can get those nifty heat-shrink caps. I also forgot to disconnect the battery, so I have the Service Air Suspension warning showing. I had the work done at a private shop locally, and the mechanic was kind enough to let me on the floor to help out. Total time from lift-up to wheels-down was 45 minutes.

So now I have a pretty clean (southern truck) two-stage compressor to sell, and a touchscreen radio as well (older style).


Oh, and while the truck was in the air, and I was wrestling with the relay up under the front fender, I got a good clear look at the drivers-side exhaust manifold, and sure enough that rearmost bolt head is snapped off, so it looks like I'm next in line for an ARP stud kit.

 

[twinmill28]

Don't remember if it was in the replacement bag instructions I had, but the quickest way to deflate the old bags is with a good razor knife once the truck is on jack stands. Since my were so deteriorated, it was like cutting paper and no problem.

Good to hear you found the experience to be quick and pretty painless.

 

[MuDnYrI]

This could very well be common place these days but about 4 years ago my compressor started acting up and the rig started sagging. I completely disconnected & removed the compressor and then unhooked the battery for a minute. Doing that will stop the warning light from coming on in the future.
Then:
I installed a new set of air bags
Bought a 3 way Pneumatic Splitter/Tee with push in fittings
Ran 1 air bag hose from each bag to the Tee
and ran the 3rd to the schrader valve in the rear.
Of course I have lost the automatic up and down but the gains aren't half bad:
1. Still get to keep the air ride
2. Can adjust up and down manually
3. Can even go up a little higher than normal
4. That compressor LBS is gone from the back (not that thats a lot but...)
5. Been working so far so good for 4 years now
6. Easier job than Springs
Of course bags and hoses will eventually go bad again so this is just an alternative method