Member Since: 21 Mar 2017
Location: Londonderry NSW
Posts: 1818
It can sink for many reasons. Does the car run? Was the car parked on level ground? maybe a leak in the air tank, known to get rusty. Filter medium in air pump blocked up or very wet. can be checked in place if you are careful. Crack between the two air lines on the air pump filter. Have you done anything to the three valve blocks as this can cause a problem.
27th Jul 2024 8:30 am
Alfadisco
Member Since: 19 Dec 2022
Location: Roma
Posts: 35
Car runs properly, was parked level in usual spot and had maintained regular height through the night, no signs of leaks in previous day, no tinkeriing with valve blocks, no exceptional drives in previous days.
It all came as a surprise, never had suspension issues before (had several of the other typical d3 issues though!)
27th Jul 2024 9:28 am
Globetrotter448
Member Since: 21 Mar 2017
Location: Londonderry NSW
Posts: 1818
For it to lose air, you have a leak. My guess would be the tank as all have gone down.
27th Jul 2024 11:22 am
ekwan
Member Since: 24 Apr 2016
Location: P Jaya
Posts: 35
The suspension DTC's have subcodes like C1A03-XX and C1A04-XX.
XX codes tell a bigger and more detailed story. Any idea what your XX codes are?
29th Jul 2024 1:16 am
ekwan
Member Since: 24 Apr 2016
Location: P Jaya
Posts: 35
The suspension DTC's have subcodes like C1A03-XX and C1A04-XX.
XX codes tell a bigger and more detailed story. Any idea what your XX codes are?
29th Jul 2024 1:18 am
Alfadisco
Member Since: 19 Dec 2022
Location: Roma
Posts: 35
Thanks for the suggestions.
@globetrotter, I don’t think the system loses air. It just went down from normal height to bump stops upon switching key on/engine off. Until that moment all was perfect. Now the compressor starts if I jump the relay but no air goes to the struts. If it was losing air I suspect some short-lived action on the suspensions should be detectable. Am I wrong?
@ekwan, the XX on the C1A73 etc are always and only 1C. And this remains the only DTC I get (from all 4 sensors). Could not find much info on the specific meaning of this 1C though… insights most welcome.
30th Jul 2024 5:23 pm
ekwan
Member Since: 24 Apr 2016
Location: P Jaya
Posts: 35
Taking DTC C1A73-1C as an example, it indicates that there is an issue with front LHS height sensor.
First of all, it requires a 5V supply from the suspension ECU. So your first job is to unplug the connector to each of the sensors and see if the 5V supply is present with the engine running (not sure if there should be voltage present with just IGN ON, but good chance there will be).
If you have voltage at all but one height sensor, there is a good chance that there is a wiring break, short etc between the suspension ECU and that particular sensor. Easy enough to trace the break, or perhaps a short.
If there isn't voltage present at more than one height sensor, perhaps no voltage at ALL sensors, then it is likely a common issue i.e. suspension ECU. At best, the connector at the ECU end is not plugged in correctly, water ingress into the connector, or even perhaps corrosion of the connector blah blah blah etc etc. At the worst, you have a duff suspension ECU, or even perhaps something as silly as the power supply to the ECU is non-existent (unlikely as the ECU seems to be deflating the suspension).
I have included a screenshot of the wiring to the 4 height sensors so you have the wire colour codes. But checking the voltages is really your 1st step.
You need to check for the 5V supply situation, report back and we can take it to another stage.
Click image to enlarge
Click image to enlarge
31st Jul 2024 2:10 am
Alfadisco
Member Since: 19 Dec 2022
Location: Roma
Posts: 35
Ekwan, thanks for the diagrams.
However, as I said live data shows that voltage supply at all 4 sensors is 5V; output instead is around zero but it increases when the car is lifted. Therefore I tend to exclude issues with the sensors’ wiring.
Compressor works properly when the relay is jumpered, it does not when the relay (even a new one) is plugged in.
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