It could also be a dodgy connection on / in the fuse board.
Is there voltage actually present at the pump when the Nano says the pump is on?
That's how I finally determined I had an intermittent pump relay.
An issue in the fuse board will bring up all sorts of odd gremlins!

Is the thermal sensor in the pump?

Yes, at the back of the motor, by the brushes. Not that easy to get to though and putting it back together can be fun (holding the brushes back while putting the back on again isn't easy).

Are you saying that the pump will run with a door open?

I did rebuild the valve block and pump 3 years ago.

Not had time today as a busy family day.... Will get on the case tomorrow!

phazed wrote:

Are you saying that the pump will run with a door open?

The pump will run but having a door open will inhibit all suspension movement. So if the system is empty, it is better to run it with a door open so all it is doing is filling the reservoir rather than trying to fill it and pump the car up at the same time. If you have a faulty door or tailgate latch so it always thinks a door is open, it will never rise and if the reservoir is already full and up to pressure it won't turn on the pump. However, if the Nano is showing rear valves open, that isn't the problem as no valves would open if it is inhibited.

Thanks again. You learn something new every day.

I will be having a good look at this later.

Used the car this morning.

Everything works quite well. Got home and lowered to access height. Left the car for an hour, plugged in Nanocom. Started car and pressed raise to normal height. Looking at the Nanocom, the compressor stayed off and the compressor is off! Left the engine idling for 10 minutes and compressor is still off with no rise. Very strange. Open to ideas.

Thermal switch show normal
inlet valve, open
pressure switch open
lower switch. Open
Raise switch open
exhaust valve close
inhibit switch off
door/disable close.

Just been having a fiddle.

Fuses all okay. Rely okay. Connector in pump box all good. No signs of corrosion anywhere. Car is a good clean example.

Car still on access height. Started car up. Pump not running at all. After a few minutes, I checked the Nanocom and it says rear valves open and then after another few minutes rear rises up. Pump still not running. Checking Nanocom and rear valves close, front valves open and after several more minutes the front rises and now car is at the standard height. Pump hasn’t run at all during that time and still isn’t.

Left car for a bit. Switched to high level. Car tries to rise and gets about 3/4 the way there with pump still not running.

Fiddled about a bit more in no particular order and pump started running for awhile without doing anything specific.

I really am confused!

Fiddled about a bit more in no particular order and pump started running for awhile without doing anything specific.

Fiddled with what, specifically?
Wires? connectors?
Or did you fiddle with nanocom only?
What got wiggled or jiggled?

It's ok to admit at this point that you gave it all a "gentle tap" with a 10 pound sledge hammer........

I didn't fiddle with wires etc.

Just with the Nanocom. I only know half of what I'm doing!

Seems to me that the pump isn't switching on when it is called for but after a while will switch on and behave normally.

Usual scenario: I start the car, (car seems a little low) car wants raising and instead of the pump kicking in, it remains off. I gently drive it when it is low and within a minute or never, it goes to standard ride height.
If it doesn't go up, I can park up, return a while later and it majestically rises after a few seconds...

At start up if the air tank is fully charged then the pressure switch will not call for the compressor to run and the suspension will rise to ‘standard’ ride height from the air pressure from the fully charged air tank alone. The compressor will not run. If the vehicle doesn’t rise then it cannot be all the air bag solenoids have failed and may well be that the inlet solenoid and/or NRV2 may be playing up and working only intermittently and after the vehicle has been driven the normal suspension bumps/vibration shake either or both into action.

I don’t believe that the solenoids have a tell back as to their actual position and, therefore, NanoCom just reports what is demanded! This may be causing confusion.

When the suspension won’t rise I would switch off and then discharge the air tank by pulling the air line out of the valve block then reconnecting it. If the compressor then runs when the car is started then I would suspect the valve block NRV2 or inlet solenoid.

Sounds reasonable. Will check tomorrow.

Cheers.

Have you got a spare pressure switch you can swap in?

If it is getting down to solenoids acting or not, have you checked the connector to the driver pack beneath the valve block?
Apparently, the pins can become loose over the years causing all sorts of intermittent mischief!
Maybe, if available try a different driver pack?
My tendency is to suspect the pressure switch itself.....
My 02 has tossed an EAS error on the dash and when looking at the error on nano, it is telling me the switch has not changed state or something like that.
I clear the error, and it goes away for months or years......I do have a spare switch in the cubby just in case it is really dodgy, or finally fails.

Used my sons professional code reader on it this morning. Did the various access/normal/high position dance several times.

Ignition on and off and repeat.

Unbelievably, it is behaving today!

So frustrating, still all working well today.

Amazing! Can’t see this lasting…

Another day, all working perfectly. Damn…

How can I look for a fault?

Very difficult, if not impossible, to troubleshoot an intermittent fault when it’s working perfectly.

Now if only the random locking and unlocking while you are driving can self cure i'll be quids in!