discovery 2 air compressor

tim wilki · Oct 6, 2018

Hi All

having a problem with my air compressor for suspension

It run for about 3 to 15 second then cuts out will not lift

Your help is needed pls

Tim

dieseldog69 · Oct 6, 2018

tim wilki said:
Hi All

having a problem with my air compressor for suspension

It run for about 3 to 15 second then cuts out will not lift

Your help is needed pls

Tim

Is your suspension at height or are the air bags deflated?

If the vehicle is close to height it won't run for long as it is only trying to achieve predetermined ride height, if your air bags are deflated then it can be that the compressor is tripping out the thermal cut out.

sierrafery · Oct 6, 2018

tim wilki said:
Hi All

having a problem with my air compressor for suspension

It run for about 3 to 15 second then cuts out will not lift

Your help is needed pls

Tim

Hi. As long as it runs but cuts out IMO the problem is not with the compressor but with the management.... the system needs a proper diagnose with tester to see if the calibration or sensor's inputs are OK

dieseldog69 said:
if your air bags are deflated then it can be that the compressor is tripping out the thermal cut out.

sorry to contradict you but there is no suct thing as "thermal cut out" in the SLS management, there is a "duty cycle exceeded" protocol which would be logged as fault and not let the compressor run untill it's cleared from the ECU memory

a simple thing is to rule out a ''tired" compressor relay by replacing it with a new or known good one but this would be a lucky scenario

dieseldog69 · Oct 6, 2018

sierrafery said:
sorry to contradict you but there is no suct thing as "thermal cut out" in the SLS management, there is a "duty cycle exceeded" protocol which would be logged as fault and not let the compressor run untill it's cleared from the ECU memory

For me that is what I would describe as a thermal cut out, duty cycle and ECU controls are the modern new speak for old timers like me

sierrafery · Oct 6, 2018

I accept your ''old school" terminology then just that in that case the ECU would not let it run at all untill the fault is cleared and to exceed the duty cycle the compressor must run more than 15 seconds

tim wilki · Oct 6, 2018

dieseldog69 said:
Is your suspension at height or are the air bags deflated?

If the vehicle is close to height it won't run for long as it is only trying to achieve predetermined ride height, if your air bags are deflated then it can be that the compressor is tripping out the thermal cut out.

Hi was ok the morning at height the wife took it and came back down will not rise but the bags get hard but with no lift?

is the cut out on the compressor and can it be replaced ?

thanks

tim wilki · Oct 6, 2018

sierrafery said:
Hi. As long as it runs but cuts out IMO the problem is not with the compressor but with the management.... the system needs a proper diagnose with tester to see if the calibration or sensor's inputs are OK

sorry to contradict you but there is no suct thing as "thermal cut out" in the SLS management, there is a "duty cycle exceeded" protocol which would be logged as fault and not let the compressor run untill it's cleared from the ECU memory

a simple thing is to rule out a ''tired" compressor relay by replacing it with a new or known good one but this would be a lucky scenario

Hi i did have a problem with the bags but changed and all working fine there are no warning lights i have not plugged in but i only have a simple tester but will try

tim wilki · Oct 6, 2018

sierrafery said:
Hi. As long as it runs but cuts out IMO the problem is not with the compressor but with the management.... the system needs a proper diagnose with tester to see if the calibration or sensor's inputs are OK

sorry to contradict you but there is no suct thing as "thermal cut out" in the SLS management, there is a "duty cycle exceeded" protocol which would be logged as fault and not let the compressor run untill it's cleared from the ECU memory

a simple thing is to rule out a ''tired" compressor relay by replacing it with a new or known good one but this would be a lucky scenario

Hi did try the relay with a 30amp one but still the same

brian47 · Oct 6, 2018

tim wilki said:
is the cut out on the compressor and can it be replaced ?

thanks

As @sierrafery has already said, there isn't a "cut-out" component, it's a bit of electronic programming in the SLABS ECU which when it detects that the compreesor has been running for too long; beyond its duty cycle, it will stop the compressor and will not allow it to be restarted until the fault is cleared using a compatible code reader.

sierrafery · Oct 6, 2018

tim wilki said:
.....will not rise but the bags get hard but with no lift?....

i dont really understand what you mean by that

.... check visually the sensors cos they used to snap at the plastic ring... only a dedicated tester can help with this a generic one is useless

tim wilki · Oct 6, 2018

brian47 said:
As @sierrafery has already said, there isn't a "cut-out" component, it's a bit of electronic programming in the SLABS ECU which when it detects that the compreesor has been running for too long; beyond its duty cycle, it will stop the compressor and will not allow it to be restarted until the fault is cleared using a compatible code reader.

Hi i have a simple code reader obd2 will this just plug in or need a special cable as i cant seem to locate it?

tim wilki · Oct 6, 2018

sierrafery said:
i dont really understand what you mean by that .... check visually the sensors cos they used to snap at the plastic ring... only a dedicated tester can help with this a generic one is useless

will check again in morning to dark now but looked ok from what i could see

what i meant is the air bags get hard but will not lift from down position

sierrafery · Oct 6, 2018

tim wilki said:
what i meant is the air bags get hard but will not lift from down position

they get hard cos they get some air in those 3 or more seconds but not enough to lift the body, if you push the ORM switch does it act the same?

tim wilki · Oct 6, 2018

sierrafery said:
they get hard cos they get some air in those 3 or more seconds but not enough to lift the body, if you push the ORM switch does it act the same?

Hi if i push it no difference

just a thought if the piston seal has warn then maybe i get some pressure but as the pressure builds maybe the piston seal/ring is not good enough what do you think???

but would that explain the early cut out ?

sierrafery · Oct 6, 2018

No, that early cut out is exclusively a management command... based on sensor inputs the system can "think" that the vehicle has reached the target height or it can be a system missbehaviour caused by a wiring or bad contact issue or even ECU problem, i dont see other way to diagnose than using a dedicated d2 tester to read live inputs while the symptom occurs... it's not complicated but the proper tester is compulsory.

Disconnect the battery and swap the sensors between them then try again to see what happens.

btw when you push the ORM do you get the bongs a flashing warning?

tim wilki · Oct 6, 2018

sierrafery said:
No, that early cut out is exclusively a management command... based on sensor inputs the system can "think" that the vehicle has reached the target height or it can be a system missbehaviour caused by a wiring or bad contact issue or even ECU problem, i dont see other way to diagnose than using a dedicated d2 tester to read live inputs while the symptom occurs... it's not complicated but the proper tester is compulsory.

Disconnect the battery and swap the sensors between them then try again to see what happens.

btw when you push the ORM do you get the bongs a flashing warning?

hi yes to the question both

btw when you push the ORM do you get the bongs a flashing warning

biketeacherdave · Oct 6, 2018

Take the pump out strip it down and clean it, there is a safety valve which will release with the slightest bit of water in it, that's what was causing my issues when ours went wrong about a 20 min job once you have the pump off.

tim wilki · Oct 7, 2018

biketeacherdave said:
Take the pump out strip it down and clean it, there is a safety valve which will release with the slightest bit of water in it, that's what was causing my issues when ours went wrong about a 20 min job once you have the pump off.

Hi thanks will go and have a look

did you have a pressure issue as well?

thanks

sierrafery · Oct 7, 2018

i reiterate and you can believe me or not: the fact that the compressor's feed is cut in 3 to 15 seconds before the body lifts to normal height is a management issue, even a new compressor with a well working system could take 20 seconds to lift the body from bump stops to normal level and the compressor's feed is supposed to be cut by the ECU only when the sensors give the target height inputs, if target height inputs are not received by the ECU it keeps the compressor pumping untill it exceeds it's duty cycle which is above 30 seconds or untill it burns out in some cases

tim wilki · Oct 7, 2018

sierrafery said:
i reiterate and you can believe me or not: the fact that the compressor's feed is cut in 3 to 15 seconds before the body lifts to normal height is a management issue, even a new compressor with a well working system could take 20 seconds to lift the body from bump stops to normal level and the compressor's feed is supposed to be cut by the ECU only when the sensors give the target height inputs, if target height inputs are not received by the ECU it keeps the compressor pumping untill it exceeds it's duty cycle which is above 30 seconds or untill it burns out in some cases

Hi i do believe in what you are telling me of course

just been out this morning started her up and up it came pressed the ORM and up again now i am confused

thanks

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