Spend the weekend wiring in the 99 spec wabco ECU and corresponding modulator to replace my broken one.

Finally got everything together, brakes bled, ECU powered, everything looks good....

Except the dashboard says Traction Failure

I've not actually driven it yet as i need to put the coolant tank and stuff back in. Scanned for fault codes and none are found. Is this perhaps normal for a WabcoD after the battery has been removed? Or do I have a problem somewhere in the wiring 🤔

Is the pump running when the ignition is turned on? Insufficient brake pressure is the most common cause of Traction Failure.

It would seem i was worrying unneccesarily, once i drove it up the road all the lights went out and it seems happy.

I do have a question mark on the brake pedal feel though. Perhaps others can chip in with how theirs feels?

Previously the pedal was very "hard", there was a bit of initial travel, then it would come up kinda solid and it felt like brake modulation was simply via pressure on the pedal.

Now the pedal is much softer. I would hesistate to say spongey but certainly very much softer than before. Brakes come on immediately at light effort like you would expect, but it no longer has the same solid feeling, the pedal moves down as the braking force increases, more like a typical car.

I'm fairly sure its always had the "solid" feel to the pedal the whole time i've had the car, so this differnce has me questioning what it should be doing.

I may well go back thru the whole bleeding routine again, its just a faff and takes about and hour and requires an assistant.

It may just be that your new modulator isn't as gummed up and partially seized as the old one and now you have a pedal that feels as it should have done all along.

okay paying attention to it when its stationary, with the ignition off and system depressurised, i can push the pedal almost all the way to the floor, its like pressing on a big spring.

If i turn the ignition on and let the system come up to pressure, the pedal moves about half as far then comes up hard.

My feeling is that its probably still got air in it somewhere... Maybe the master cylinder section.

Yes, if it will go to the floor without pressure in the system, that would suggest air in the manual hydraulic circuit. Looks like you're going to be bleeding it again....