Hello all,

I am looking for a replacement air solenoid valve, part No GM19333035 for my air suspension on a 2005 H2, it's the twin compressor type. Does anybody know where to purchase this item as GM service dealers state that this item is now discontinued. They must be available somewhere as you can still purchase the complete air suspension module which has this valve block included, however I don't want to spend $2500.00 to $3000.00 getting it to Australia when I only want the solenoid valve.

 

May I ask what's the problem with your old one?

Think they are called Inlet Valves. My H2 is also a 2005 twin compressor system which I've now learned a lot about, including de-potting and reverse engineering the AS Control Module electronics.

I was faced with the same problem, in the end I stripped my valves down, cleaned and reassembled them, I have to say the weakest parts were the air-pipe connectors which seem highly susceptible to corrosion.

Here is a of your valves, hope it helps

 

de potting sucks lol... had to do that for my xj6 series 3 climate control brain box to get to the embedded relays.

 

Senior,
Thank you for your reply, however the solenoids are very clean and working fine, the issue I believe I have is the sensor connected at the end of the valve block is reading 43 psi at atmosphere when the air lines are off and reads 43 psi when under pressure. Atmosphere pressure should be around 15 psi.

 

As it happens I have a valve assembly infront of me (but sorry it's needed)

So I took it apart (yes it unscrews) it was "well and truly" thread-locked (probably loctite) so took some effort to remove (27mm A/F wrench rqd) If you do attempt to remove it be careful with the valve module's plastic housing, also before re-assembling be sure to pick-out every trace of thread-lock.

The sensor's threaded part is brass, 11.6mm in length,18mm (0.712") OD and 1.5mm (0.059") pitch. There is an O-Ring seal (2.5mm thick by 15mm ID)

The sensor is a 3-Pin device with Pin1=+5V Ref, Pin2=0V Ref and Pin3=Signal (0-5V) which connects directly to the AS Electronic Control Module Pins 3, 19, 11 respectively. The sensor is probably a piezo-electric pressure transducer and bears the P/No >PBT-GF20< on it's plastic connector.

I mention the above as you might be able to replace it which may be easier (Heavy Duty Pressure Sensor/Transducer 3-wire 0-5V)

Things to check:-

1. Check voltage across connector Pins 1 and 2 this should be approx 5V (probably 4.5V 'ish) If not check the Ride-Height sensors/wiring for any damage or shorts (they use the same 5V Ref). The ECM monitors the 5V Ref current and can disable it if too high! Check the RH sensors on the TECK2 they should each read around 2.6V at normal height.
2. Unplug the pressure sensor and short connector pins 3 to 2 (OV) check the reading on the TECH2 this should be low (probably 0 PSI)
3. Repeat for pins 3 to 1, check the reading on the TECH2, this should be high (maybe 100 PSI but its just a guess!)

If the TECH2 values seem sensible, it does suggest there is an issue with the Pressure Sensor.

Otherwise check the wiring to the AS ECM, any contamination or water ingress can drag the sensor input up or down. To verify, unplug both ECM and sensor and check Pin 11 doesn't connect to any other pins, any value e.g. less than 1M Ohm would be bad.

If the ECM isn't behaving sensibly it suggests it is faulty (expensive)

The Pressure Sensor seems a very robust so may not be the the root cause, hopefully is not the ECM which leaves the wiring and/or the Ride-Height sensors.

Attached is the connector pinouts and a pic of the sensor (I'm on vacation from Sunday for 2 weeks)

 

Oceanbrave,
Thank you for all the advice you offered, I have checked my wiring and voltages and confident all is fine, so it appears still to be a pressure transducer issue. After seeing your photo of the sensor separated from the valve block, I also removed my sensor, I was not convinced it would screw off as GM don’t offer it as a separate part, only complete with the valve block.

I can’t find anything anywhere relating to a replacement or aftermarket sensor/transducer to suit the air suspension on a H2, however I have found similar 3 pin sensors with the same electrical connector and thread to suit Volvo truck air brakes and a few other suppliers, however I don’t know what the maximum & minimum pressure rating is for the Hummer sensor, do you know what the 0-5V reference value corresponds to in pressure?

Thanks again for any assistance you can provide.

 

As mentioned, if you have access to a Tech2 you might be able to discover the range by connecting the Sig input to 1st ground (min pressure) the to 5V Ref (max pressure) i.e. without the sensor connected

Unfortunately I'm not back till next week so it's hard to help remotely..

 

They are selling these compressors systems new on eBay. I don't think they are coming from GM, but rather coming from the original manufacturer. Perhaps it's worth sending a PM via ebay to one of those sellers to see if you can still get various parts you need.

 

Just got back from hols.

If you've had no luck obtaining an OEM part, this is a screen shot of the related Tech2 page, their readings were 42psi at 0.43 Volts with the suspension at normal height and with the engine running (yes the Tech2 provides both values!)

Sensors usually farneg from 0psi (0V) upwards so the H2 sensor range is approx 100psi/volt i.e. 0-500psi at 0-5V

There is a slight scale error in my readings but it's close enough to fit the 500psi range above.

Hope this helps.

 

More feed back for Hmmr

I recorded the PSI Vs Voltage readings from the Tech2 whilst hitting the extended ride-height switch to get some more data points to extrapolate from.

These were the values:-

Volts (x) PSI(y)
0.43 42
0.49 44
0.59 46
0.98 58
1.08 60
1.24 66
1.35 69
1.37 70
1.47 73
1.61 77
1.69 79
1.76 82
1.84 84
1.88 85
1.96 88
2.04 90

Interestingly the start point is the same 43psi you recorded. Also the sensor on my replacement AS Unit is different from my old one i.e. the connector is different (smaller), so it looks like there are variants out there. I also get this value with the engine off.

If you extrapolate the y=mx+c values you should get m=30 (i.e. 30psi/volt) and a "c" value of 28 (i.e. pressure at zero volts), again interestingly of you add 15psi to the start point you get 43psi !

The attached graph shows the theoretical relationship between pressure and voltage, its a very close fit to the recorded values.

It was my intention to connect-up my old sensor to get the atmospheric value, but as I said the connectors are different. However, without the engine running the compressor is off and the inlet valves closed (valve current is 0), so there should be no pressure in the system i.e. at atmosphere. Again 43psi is what the controller reports-back which seems odd.

So contrary to my original estimate, the sensor range seems to be 0-180PSI at 0-5V not the 500 PSI range based on a single value, have to say 0-180 range seems more sensible.

It would have been better to work with real pressure and real voltage readings but that's a little hard to do. Anyway given it my best shot.