E53 4.4 2004 Gearbox loss of electrical power

[Jim M3]

Hi,
New to the forum and X5 ownership.
Picked up my X5 12 months ago to tow car trailer mainly and up until 2 weeks ago it hasn't missed a beat.
Pulled out of a junction and revs went up but road speed didn't then the gearbox bangs badly. Car does not go into Gearbox Failsafe. When this problem occurs the gear selector on the dash flashes.
Booked it in to a auto box specialist for a potential rebuild. Couple of days later I get a call to say it looks like the gearbox is losing electrical power when this happens and the only fault code coming up is 5014 Power Supply. He has his Auto Electrician look at it and he confirms the gearbox is losing electrical power intermittently and causing the banging etc. He has had a look in to it but has drawn a blank. I picked the car up on Saturday and it drove absolutely perfectly through all gears, kick down etc. then on Sunday it has the problem again.
I have had a good search on the internet but I cant find any threads about a similar issue and wondered if anyone on here could shed some light on this?
Thanks in advance,
Jim.
Mileage is 114,000 Gearbox was serviced 2000 miles ago along with software update and has just had new oil/filter as part of investigation work. Car is facelift 6 speed model.

[henrym3]

I'm reluctant to offer advice as you say an auto electrician has looked so one would assume that he disconnected all the electrical connections and checked for dirt/water ingress, sprayed with contact cleaner and refitted, including EGS control module and fuses that supply the power. I notice that there are EGS modules on the bay at around £130/150. Not suggesting you throw parts at it but if an "expert" auto box man shrugs his shoulders what can you do, except take it to another "expert". Sadly an overused term.