P38A Compressor

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J L Carr

J L Carr

Active Member
Posts
360
Location
Hemel Hempsted
Hi Guys.
Help needed, I am not getting any power to my Air suspension compressor all was working fine the day before but now nothing, done the usual checked the fuses and relay, changed them but to no avail. So checked if any power was coming though the main cable and nothing, the only way I can get it to run is with a bypass power supply via the battery to pump it up, checked if the compressor is working as I have 2 tried them both and both are ok, but changed over to my spare and still the same. So has anybody got an idea of what may by the problem. Thanks.
 
J L Carr said:
Hi Guys.
Help needed, I am not getting any power to my Air suspension compressor all was working fine the day before but now nothing, done the usual checked the fuses and relay, changed them but to no avail. So checked if any power was coming though the main cable and nothing, the only way I can get it to run is with a bypass power supply via the battery to pump it up, checked if the compressor is working as I have 2 tried them both and both are ok, but changed over to my spare and still the same. So has anybody got an idea of what may by the problem. Thanks.
Click to expand...
Check the main connector for loose contacts.
 
Hi, not getting any power up to the main connections as I stripped back the sheathing about 200mm back down the main power cable up a volt meter on it started the car up, but no volts coming through. So that's why I checked both fuses and relay,so now puzzled.
 
J L Carr said:
Hi, not getting any power up to the main connections as I stripped back the sheathing about 200mm back down the main power cable up a volt meter on it started the car up, but no volts coming through. So that's why I checked both fuses and relay,so now puzzled.
Click to expand...
Gave you got Rave? I can't remember off hand what supplies the power,probably one of the mega fuses.are they intact and clean?
 
Just checked the 30 amp No 2 fuse and it's ok,gave the 3 wires a volt check and till nothing from the main power cable, but I have power coming through a small black and purple cable in the block never noticed if this had power in the first place I thought it was an earth. It runs into the orange cable in the compressor block. So unless there is a hidden fuse or relay still lost.
 
J L Carr said:
Just checked the 30 amp No 2 fuse and it's ok,gave the 3 wires a volt check and till nothing from the main power cable, but I have power coming through a small black and purple cable in the block never noticed if this had power in the first place I thought it was an earth. It runs into the orange cable in the compressor block. So unless there is a hidden fuse or relay still lost.
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From memory if you earth the Orange wire and the compressor runs you have a thermal cut out problem.
 
Hi Guys.
I'm not even getting any power to the main 30 amp fuse nothing to either fuse 44 or fuse 17, changed the whole lot and still nothing even renewed relay RL20 just to be on the safe side. But there is no power to the whole system, so that's why I'm wondering if there is a hidden unit/fuse say behind the glovebox or somewhere. There is no hard fault to the suspension at all as myself and my son was under the car the day before and it went up ok and came back down ok. Baffled to say.
 
Mark Piercy said:
@Datatek, any ideas?
Have you checked the EAS for faults to be sure?
Click to expand...
Thermal trip will cut the power as others have said so will a hard fault and the pressure switch can inhibit operation. There are no hidden fuses or relays.
A duff fuse box can also cause problems. As far as I know from memory, F40 should have power when the ignition is switched on regardless of any faults etc.
 
Well done a re-check and still no power to F40 with either the ignition on or off as well as the other 2 fuses, is the a jumper I can try to the relay to see if that area is working.
 
J L Carr said:
Well done a re-check and still no power to F40 with either the ignition on or off as well as the other 2 fuses, is the a jumper I can try to the relay to see if that area is working.
Click to expand...
Is the relay switching? If not fuse F40 doesn't really matter. Putting 12 volts on pin 5 of the relay socket will operate the compressor. You could try checking the Purple wire from the compressor, it should be at chassis ground potential.
It does sound like a wiring or fuse box problem.
 
Hi Datatek could you tell me whitch is pin 5 on the relay as per picture, as you can see there is only 4 pins and as for the purple wire the one in the picture is the main power wire, the blue wire is my temporary power wire to make my compressor work.
20200723_182122.jpg
20200723_182216.jpg
20200723_182202.jpg
 
Hi Guys. Well tried it again but to no avail, so went back to hard wiring the power so ran the compressor till it told me the car was at road height but then looked at the car and here's the best laugh, passenger side front and rear at off road height front drivers was at road height but drivers rear never moved from the bump stops. So that ****ed me right off, dived into the shed to find an old valve block complete apart from acouple of bits so swapped the lot and low and behold the compressor ran and thd car came up to normal road height, so checked over the unit I have just taken out and noticed this to the suspension control unit, by the looks of things this was at fault. Thanks for your help (again) and imput. Pictures of the unit. As you see the back look a bit odd as the other one I have the back is a black colour.
20200724_154024.jpg
20200724_154016.jpg
 
J L Carr said:
Hi Guys. Well tried it again but to no avail, so went back to hard wiring the power so ran the compressor till it told me the car was at road height but then looked at the car and here's the best laugh, passenger side front and rear at off road height front drivers was at road height but drivers rear never moved from the bump stops. So that ****ed me right off, dived into the shed to find an old valve block complete apart from acouple of bits so swapped the lot and low and behold the compressor ran and thd car came up to normal road height, so checked over the unit I have just taken out and noticed this to the suspension control unit, by the looks of things this was at fault. Thanks for your help (again) and imput. Pictures of the unit. As you see the back look a bit odd as the other one I have the back is a black colour. View attachment 215420 View attachment 215419
Click to expand...
Don't know what you did but only thing you show that has anything to do with compressor is the pressure sensor. However a duff controller can cause the ECU to have a fit.
 
wammers said:
Don't know what you did but only thing you show that has anything to do with compressor is the pressure sensor. However a duff controller can cause the ECU to have a fit.
Click to expand...
Hi Wammers. I gather your talking about the green unit with the 2 red wires coming off, all I know is I tried eveything yesterday but nothing was happening but today after changing the whole unit it's all working. Again Thanks for All your help. :):)
 
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