While driving along the motorway today my rear airbags (which have never given me any bother) suddenly went flat (within 200 yds.) The compressor does not seem to be running and no warning lights came on until after I had pushed the up button on the dash to try and raise the vehicle. Have not tried anything and would appreciate all ideas and any help.
sierrafery
Well-Known Member
There are some tests to do...
1. how familiar are you with this system and it's components?
2. are u up to improvise some wiring to make tests?
sierrafery
Well-Known Member
The worst scenario is that u had a leak(bag probably)... the compressor worked continuously to compensate the lost air and it burnt out....then the air leaked out from the system
If the fuse and relay are good u must see if it's a management or compressor/wiring issue. For that u have to unplug everything in the compressor housing, improvise a wiring as to feed the compressor and the two air supply valves at the same time... if u feed these and it starts to rise let it untill the aprox normal level and cut the feed. Leave everything unplugged and wait... if there is no leak along the system it can stay levelled for days dont worry... at least u'll know it's something else.
Check visually the ride height sensors/plugs/wiring cos if there is a problem and the back went down to the bumps the ECU might not get input to rise it back
Enough for now... if u will need further guidance we'll speak again
If the fuse and relay are good u must see if it's a management or compressor/wiring issue. For that u have to unplug everything in the compressor housing, improvise a wiring as to feed the compressor and the two air supply valves at the same time... if u feed these and it starts to rise let it untill the aprox normal level and cut the feed. Leave everything unplugged and wait... if there is no leak along the system it can stay levelled for days dont worry... at least u'll know it's something else.
Check visually the ride height sensors/plugs/wiring cos if there is a problem and the back went down to the bumps the ECU might not get input to rise it back
Enough for now... if u will need further guidance we'll speak again
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Ok, thanks for all that sierrafery. The fuses seem to be fine and I swapped the relay with the one for aux so that seems to be ok also. I wired the compressor straight to the battery, disconnected the centre air inlet/exhaust pipe to check my connections were the right way round and the compressor ran well. Then I disconnected the SLAB unit so I could connect wires straight into the two valves harnesses and straight to the battery and bingo, she came up like a cork out of a bottle. I then disconnected everything as you suggested and its still at the same height as it was after an hour so I guess no real bad leaks in the system. So we know the harnesses to the valves from the SLAB are ok and the compressor works fine and the bags are ok so where do we go from here????? I have this horrible feeling it might be the SLAB but how do I check I am getting a feed into the SLAB. My three sisters for the ABS have been on for a year or so now and as it’s the same SLAB, could there be a connection. I think one of the sensors had a blip as ABS and traction control seem to work fine. A good call by you so thanks and what next?
sierrafery
Well-Known Member
OK then, at least now you know how to inflate the bags so u will be able to use the car untill we get to the end of it. Next reconnect the SLABS ECU and see what happens...if it will go down again it means the ECU opens the 2 air supply valves and the exhaust valve... this could be due to bad input from the height sensors or as u supposed an ECU missbehaviour. Disconnect the car's battery and swap the sensors between them or if you know they are old enough u better use the car as it is(with springs inflated and SLS disconnected) untill u fit two new sensors... dont forget that what ever you do at the sensors disconnect the battery first or u'll need recalibration with tester...albeit to scan the ECU if u can get near a tester would be the best option(and u'll see the ABS fault as well)
. Next reconnect the SLABS ECU and see what happens...if it will go down again it means the ECU opens the 2 air supply valves and the exhaust valve... this could be due to bad input from the height sensors or as u supposed an ECU missbehaviour. Disconnect the car's battery and swap the sensors between them or if you know they are old enough u better use the car as it is(with springs inflated and SLS disconnected) untill u fit two new sensors... dont forget that what ever you do at the sensors disconnect the battery first or u'll need recalibration with tester...albeit to scan the ECU if u can get near a tester would be the best option(and u'll see the ABS fault as well)
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Right, I have now reconnected everything up to where it should be and as soon as I connected the green block to the SLAB it gentle let the back down to where it should be and it has been there for the last few hours. I cannot lift the back end to high mode but that is un important at the moment. I will now go and try the car to see if the compressor cits in and out as it shoul do. The warning light is still on on the dash. Getting to a tester for a Land Rover here in rural central France is like finding hens teeth.
sierrafery
Well-Known Member
There is a nice guy nicknamed Thebiglad, member of this and other LR forums who lives in central france and he has a hawkeye if i recall well. The fact that u have the warning on and according to the symptoms my first call would be a sensors erratic behaviour...they are not very expensive so if u can't read the fault codes u better replace them...though that guessing type of diagnose is not the best.
Good luck
Good luck
So what do you know. Started in up, the compressor kicked in to lift it a little, then warning light went out and I drove it for about an hour as I had a recovery to do and it all behaved perfectly. Hope it is still sitting high tomorrow and that should be an end to it. what really went wrong I am not sure but lots of connections were played with and I hope id does not come back. Still, I've learned a lot and would just like to thank you very much for all your help and I am sure we will speak in the future. I know thebiglad from a couple of years ago so think I will get in touch and see what he has got. Thanks.
