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Yes, mine is the first generation single compressor setup. The main relay is on the firewall below the hydroboost/master cylinder and you pretty need to stand on the front tire to reach down to get at it. The earlier setup works on all the same principals though and compressor shelf can be replaced with the newer style by just plugging the newer type in if it were to need to be replaced. On looking a bit this morning I'm thinking it might be hydraulic oil leaking onto the front relay wiring. It appears as though my hydroboost unit has started leaking and there is power steering fluid running down the wiring to the compressor relay. I'm wondering if some is somehow getting into it. I did pull the relay off and it bench tests fine. Have a rebuild kit ordered for the hydroboost now. Also on looking at the brake fluid that looks like motor oil I'm guessing no prior owner ever flushed the brake fluid so I'll take care of that as well when I rebuild the hydroboost.
When the relay contacts open/close they may "arc" a little and this burns the oil causes them to stick. It will be interesting to see what you find, keep my fingers crossed...
I am still without resolving my solenoid valve sensor problem, however I have noticed another member Brett has made up a aluminium valve block with a pressure sensor and solenoid valves fitted, so hopefully he has some answers to where I can get a replacement sensor.
Over the last 4 months 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. In addition I have been in communications with the global sales manager at Dunlop systems in England who has been helpful with suggesting a distributor who can assist me, however the distributor needs to purchase the sensor from Dunlop and the manager there has now gone silent and not replying to the distributors requests for help, so I just gave up, then I noticed Brett’s post in the forum, so hopefully He may have some answers.
Indeed the aluminium valve block idea is a very innovative solution.
In your earlier posts you said "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."
It seems I may also have the 15psi atmospheric anomaly, did you notice that mine also read 42psi?
I'd be tempted to remove and test the sensor in some way, perhaps stick 5V on it, connect to a DVM then applying some pressure to it.
It would be a shame to do all that work only to find the transducer was OK and the problem lay elsewhere.
If I get time I'll try and devise a test you can replicate at home.
It is odd that your readings are the same as my, so if that’s not the problem ,then I can’t think of anything else as I have replaced everything in my suspension module other than the valve block and the solenoids are working perfectly so the sensor should be it, especially with the readings I recorded, however you recording the same readings does concern me, it makes no sense?
I am in & out of coverage for the next 2 weeks so replies may be slow and further testing will resume when I get back.
, not saying this a perfect match but its close and there are lots of others. Perhaps you could get a machine shop to make a short extension (1/4 NPT hole to M18x1.25 thread)
It's been a few years since we communicated and I was hoping you may be able to assist me with a problem I had back in 2019. If you remember I had issues with the pressure sensor on the air suspension solenoid block, it was only reading 43psi under pressure or open to atmosphere, it never changed.
I managed to get a new replacement out of Dunlop via a distributor, however the connection plug is smaller than the original and I noticed in one of your earlier replies you stated you also have one. Did you modify your original air compressor kit with the larger plug to accommodate the replacement smaller plug, ie wiring changes to fit a smaller plug to connect to the new solenoid block, or was it just part of a separate air suspension system?
My problem is I now have a new solenoid block with the smaller connection with the original wiring harness that has the larger connecting plug. I have purchased a new plug to mate with the solenoid block and now I need to find out which pins in the new plug represent the same in the old plug. The old plug is a 4 pin with only 3 being used and the new plug is a 3 pin in a T shape. They are both different shapes and the pins don't line up so I can't assume anything with reconnecting the existing wiring into the new plug. I have attached a page out of the service manual with a diagram of the plug fitted to the original solenoid block and I have drawn the view of the socket looking at the new solenoid block. would you be able to number the new smaller view from 1 to 3 as per the original. Both views of the original and smaller plug are looking into the sensor fitted on both blocks, it is not looking into the loose mating plug.
I know pin 1 on the original larger block plug connects to 3 on the suspension module and 2 connects to 19 and 3 connects to 11 so if you are able to mark up 1 to 3 on the drawing that would be very appreciated.
I assume the middle of the T on the smaller plug will be No 3, and the other 2 pins could go either way and this is my dilemma. Thank you for any assistance you can provide.
Hmmr ditto Happy New Year, yes it's been a while and a lot of history in this post, my goodness I've only managed to re-read some of it !
Again I'll do my best to help if I can, it would be really great news if you found a compatible replacement valve assembly. Q. Are the air-fittings the same?
Apologies if my earlier posts were misleading, the spares I have here are all original, so no modifications required.
Be aware that you pdf shows the new sensor looking into it's pins BUT the "Old Sensor" looking into the wiring harness so pins 1 and 2 looking into the sensor will be swapped !
Your image shows the familiar round pressure sensor connector, and the rectangular solenoid-valve connector.
The comparison between your image and the original sows they look remarkably similar, I'm assuming you mounted the old sensor in it otherwise I'm a tad confused about the connector?
Your pdf suggests yours is a very different sensor connector, do you have any pics of it or a P/No, anything would help, without details its difficult to speculate on the wiring, so it is indeed a dilemma.
Going back through your posts, how did you establish whether it was the Sensor or an AS-ECU fault? - just curious.
A fault with either could cause the voltage to "stick" so to be double-sure, un-plug the sensor, short pins 2-3 and check the psi value and voltage on a Tech2, it should read 0V / 30 psi or thereabouts. Or check the sensor with 5V and a multimeter by applying some pressure to manifold (may be this is what you did?)
Based on my original measurements (see earlier graph in post) I concluded the sensor pressure range was 30psi to 180psi, this is actually supported by GM, however it seems a very odd range, 0-150 psi or 0-200 psi sensors are more common
Pressures sensors quoted as "0-1.2 MPA 5V" (0-175 psi) are a close match such as
. It looks to have a very similar connector style to your PDF (but still doesn't show the wiring)
However I managed to find similar sensors with similar connector styles like your pdf which may help (but can't guarantee)
Be aware your new sensor needs to match both voltage (5V) and pressure range, otherwise AS operation could be unpredictable.
I've just hooked-up mine to a 5V bench PSU and it reads 0.486V which I presume should be ambient pressure of 15 psi (but that does not align exactly with my chart)
Thanks for the reply. The new pressure sensor I have is complete with solenoid valves, it's a factory unit purchased from Dunlop who I believe made them for GM. If you have a late service manual it may be shown in there with this smaller plug and numbering I need.
I note your comment about the view on my pdf, it was not clear so I have attached a photo of the loose plug numbered 1 to 3, is it correct or do I have 1 & 2 around the wrong way.
I have also attached a few photos of my revised air compressor system, upgraded with pumps that actually work, (they use similar power & amps as original). The trick was resolving the exhaust valve as no new modern pumps have discharge solenoids on the compressor head, so I piped the supply lines into a new manifold with a separate exhaust solenoid (using the same power, ohms & amp) and it works fine.
