Hi, did you ever replace or clean the filter? If not do it, not compulsory to buy a new expensive one, clean it well with carb cleaner or similar and compressed air, move with talent and clog the port with a rubber bung or something as to not lose much fluid while it's removed.. as long as you see serious fluid activity in the reservoir at idle you are on the safe side, as MJI said it's possible that the ECU to make tricks as well , they are not the best piece of engineering when it comes to fault codes but fortunately the market is full of cheap working ones due to the de-ACE hysteria of those who are getting rid of the ACE due to a leaking pipe based on the statements of the schmucks who are are saying that this system makes no difference, IMO that's a psychological thing named "cognitive dissonance - the engine of self justification", the same with converting the SLS to coils
though if you keep getting relay fault codes it can be an intermittent bad contact on that path so your plan with checking the fusebox's plugs is a quite inspired move, happened to me too just that there were some other complementary(not vital) issues too, give it some contact spray... also the pressure transducer can make tricks without a fault code to be stored. Good luck
Since last posting I have removed cleaned and replaced the filter, topped up the liquid, (it lost very little) removed both fuse and relay and used contact cleaner on both though they didn't look dirty.
Separated the yellow plugs two halves and used contact cleaner on them, again ,they looked no different than before, i.e. clean.
Unbolted the fusebox from the car and the three wires at the front. Disconnected the two plugs that clip in on the top, turned it over and removed the plug that goes to the relay, cleaned that connection both male and female.
Put it all back together and drove around for quite a long time, once the engine got warm according to the temp gauge in the cab, stopping every now and then to do an "ignition off - restart" cycle until eventually the light went right out instead of staying amber. I left the vehicle and went back to check 5 minutes later. The light still went out.
But 1/2 an hour after stopping the engine, it went back to staying on amber.
The tow codes it puts up on my Foxwell are 0A06 - "Pressure signal out of range." This disappears once the amber light goes out.
And 1006 - "The main relay test has failed" which remains there even when the light has gone out on start up. Which makes absolutely no sense to me at all.
Once the light was out I tried to download or "save" live data. I didn't seem to be able to save anything that made sense. Which I am sure is down to me failing to do it properly. As far as I knew, all I had to do was to get it to the "live data" screen then click on "save" but somehow it doesn't seem to have worked, or it has but hasn't saved what I thought it would.
I have to do other stuff for a bit but I will revisit this later.
And I will reread that thread where you talked about bridging two contacts in the relay plug as I think this may be another way of getting live data.
Still thinking this must be an electrical fault, just wondering which bit of electrical apparatus to buy first.