Just fitted the exhaust manifold/turbo/downpipe and all new oil/water pipes back on and filled with antifreeze.
Car started fine and it seems I've not made anything worse, no leaks and runs (idle/revving stationary) fine.
After about 5 mins of idle/revving the 4x4 light appreared, static not flashing.
Restarted car and its off, fine. But thats the first time its done this since replacing the accumulator/valves etc.
Any reason why revving the car up to 5.5/6k whilst static (it didn't appear when idle) would cause the 4x4 ECU to get confused and stick the light on?