P38A Low Brake Fluid

Haven't been around for a while but hello to one and all.

'97 4.6 - message centre tells me the above.
I've checked the fluid level with the engine running and it's fine - so bridge the level switch to no effect.
Checked loom to BECM and found to be ok. Checked earths around inner wing area on offside, also ok.
Swapped ABS ECU for identical item, no that didn't work so put original one back.
Took vehicle to specialist who hooked it up to an Autologic diagnostic system and it wasn't able (for some reason) to access the ABS ECU.
In the process now of changing the ABS modulator but I'm a bit doubtful it's going to be the cause of the problem.
When starting the car with the handbrake off (in park, obvs) the red warning light stays on until the brake pump has done it's thing and then goes out along with the TC lamp. After about ten seconds it reappears, tells me the brake fluid is low.
Irritatingly there is nothing wrong with the car but of course I can't get an MOT on it.
Maybe one of you guys has had a similar experience or will have a pretty good idea as to what it could possibly be - my wife doesn't like me thrashing around chewing the carpets any more

No leaks on the system then? Does the pump function properly?
Is the sphere recent?
Does the abs function?

Check the pads. Changing them sorts the problem on another site.
Check level with engine running as well.

Checked with engine running and the ABS lamp extinguishes at around 5 mph.
Yes, have read on the other site about the pads being changed and the problem going away but I can't really see why it would.
I did think about the sphere and whether it has failed and dumped it's gas into the modulator or something.
It looks quite elderly so I might change it even for no other reason it's age.
The vehicle had no braking issues at all before this cranked up.

When was you fluid changed properly?
As in the whole procedure and by the book?

In the midde of ABS modulator renewal at the moment, hope to finish the job soon.
Have Genuine Workshop Manual - old skool - one that you have to turn the pages and can put bookmarks in.
Am doing bleeding process to the letter.

Enough said! I hope you are able to fix and share, good luck

Fergie46 said:

In the midde of ABS modulator renewal at the moment, hope to finish the job soon.
Have Genuine Workshop Manual - old skool - one that you have to turn the pages and can put bookmarks in.
Am doing bleeding process to the letter.

Click to expand...

All you needed to do was change the tank. Brake fluid it topped to MAX level with ignition on when ABS pump stops.