Can't bleed the abs pump

[johnnyhillen]

Hi

I'm refilling the car with brake fluid after amenities information years rebuilding the car. I was having issues getting the brake fluid to flow. Eventually got the fluid through the abs unit for the front brakes and they bled to the calipers easily. The single output to the rear brakes is a different matter. I cannot get anything to for through it. There's a strong solid flow to to the abs unit but nothing coming out. I've tried:
A brake vacuum pump on the outlet.
Pumping the brakes with a one way valve on the output.
I've used a syringe to try and get fluid in through the outlet.
I've used a thin wire to make sure the inlet and outlet aren't blocked.

I have only just managed to get a very small amount of brown cloudy bubbling liquid out but now it won't let anything flow again.

I have read that your can activate the abs pump manually by applying 12v or shorting a fuse/relay in the fusebox but I can't find anything more than a reference to bring able to do it. Does anyone know how to do this or any other ideas.

Thanks

[green_rs13]

could you trigger the ABS by having the ignition on and spinning the front wheels and not the rears, or something to that effect