03 H2, yes I know another air suspension question (I did search extensively).

H2 decided to give me a service air suspension alert (very cold out).
By the time I got to my destination rear was flat/low.
Air compressor wont turn on to inflate airbags.
Fuses are good.
No door ajar messages and all interior light turn off (so dont think door triggers).
Disconnected battery overnight, when battery is re-connected can hear pump do quick pump.
When air switch in hatch is turned on it runs great, sounds normal and runs no problem for a minute (I turned off at that point, would continue to run)
On startup the compressor simply doesn't make a sound (usually pumps for a second or 2 and turns off)

100% compressor is alive and at least sounds like its working normally when triggered in trunk but will not start on its own/will not activate automatically.

Is it possible to somehow manually trigger onboard air compressor to inflate airbags?
At least to get me to the shop?

I hooked up a external air pump and tried to add air through schrader valve in trunk but no dice, pressure gauge on ext. comp. raises but no change in suspension height.

Any idea what else to check?
I have read about a relay under brake mast. cyl. but cannot find it? Any pics? or instructions?

There's gotta be a way to get airbags to pump up,
it is possible that there are small leaks in airbags but would never really squat when parked and the pump simply wont start automatically.


Thinking its simply the trigger signal not being sent OR there is a "vent/airdown solenoid" stuck open and system wont activate while stuck open.

Lost air quickly once service air suspension light came on.

 

03 so is yours is a single compressor system? Twin systems I'm very familiar with, singles not so much but basic operation is the same.

Getting the DTC error message(s) could help resolve the issue and/or provide clues.

Forcing air back through the trunk air-valve won't work alone, each bag has an inlet-valve that needs to be operated at the same time (which is how the system works)

Someone managed to manually inflate the bags -I quote "I did the quick fix and unplugged my suspension system and joined the two air lines from the suspension bags together with a tyre valve and manually pumped them up to my desired level"

Sounds like your AS relay is OK since the rear air-switch operates the compressor, but have you tried inflating a tire? If this works then the system is capable of pressurisation which is good, if not it could be an exhaust-valve issue.

On a long-shot, inspect the left+right height-sensors, make sure their connectors are still inplace with no signs of damage (easy to inspect) any major problems here and the compressor will not operate (though probably this is not the issue)

Losing air rapidly from both sides is catastrophic, so inspect the AS Unit and make sure all the air-pipes are in-place. The inlet-valve assembly ports can become corroded over time, the 3 pipes are only held-in by friction so one could have come free (never lubricate!)

A TECH2 scan-tool has the ability to inflate (plus a whole lot more) but I suspect the problem will re-emerge once the truck starts-up again.

The electronic Air-Suspension Module monitors a range of parameters such as air-bag pressure, sensor range & activity, sensor over-current, air-valve over-current, exhaust-valve circuit, compressor over-temperature, compressor-relay circuit. Everything is electronic, so alas there's no inflate relay.

Losing pressure from both air-bags probably means it's something in common with both, this suggests a problem with the inlet-valve assembly (hopefully not)

So it may be necerssary to pull-out the AS Unit, but get the DTC if you can and take it from there.

Keep us posted.
(just edited this post so please re-read)

 

Thanks for the advice, still waiting on tech2 sadly.
Will post the fix or spring install, lol.

 

Post any codes you find or clues you may have, we'll do our best to help.

 

Do yourself a favor and convert to coil springs this will drive yourself nuts trying to figure this out Strutmaster makes a great direct fit too many things to give wrong on our older vehicles. But you can try 1 more thing put a Jack right under the hitch reciever and Jack it up to the factory height turn on the extended height button and it might come on

 

The lack of spares is the main issue, otherwise the system is reasonably straight forward and the Air-Suspension is a good system.

Admitting defeat and fitting springs would drive me nuts ... but its the way most folks seem to go...

 

I know I have had mine since brand new in 2006 I kept the air ride for 14 years after replacing air springs twice matter a fact about a month ago I replaced them again and two days later the compressor blew hows that so I finally did it and it rides and handles better there are just too many variables that can go wrong and they will what year is yours and how many miles mine has 98000 well good luck

 

Intersting mine was also brand new in 2006 (I'm it's 2nd owner) and it's done 89000 miles. Its original AS ECU died so i bought a complete 2nd hand AS-Unit and fitted it, which solved my immediate problem.

Then I took the old ECU, un-potted and reverse-engineered and fixed it (electronics is my background). I also dismantled the old inlet-valve manifold and refurbished it, so now I have a complete spare AS-Unit ready for any future issues.

So doing all this made me pretty familiar with the whole system, except for the software/comms side (I'll get round to that eventually)

 

Well if that makes you happy I can understand it but for me just too complicated and expensive I'm real happy with the conversion