Join Date: Oct 2011
Location: United Arab Emirates
pressure drop could also caused by sele oil leak.
If pressure exceed 55 then for sure accumulator is broken.
If pressure dropping below 45 then this will trigger the pump to run.
When pressure stays below 45, it doesnt mean that your accumulator are shot, it might be problem with the relay/pump.
If you don't have oil leak and pressure is going down very fast, say 55 to 45 in just 10-30s when engine on/N, then accumulator is broken.
For the 2nd part, if you don't have the problem with pressure/accumulator/relay/pump, then it should be the selespeed sensors.
See if you have signs like blinking gear numbers, wrong gear indication, not able to shift into gear from N.
I guess when sensors not giving the correct position then ECU will revert the gear to N.