Rd 2.8 TD glow plug light flashing

Hi guys I was hoping for advise on this problem- I put in a new RD 2.8TD into my 97 patrol but the glow plug light still flash’s after starting. I have had two auto Sparky’s look at it. Both agreeing there is power to the plugs for pre ignition. One sparky suggested to replace the controller box. The glow plugs are correct for the front 123 cylinders and 456 aswell ( 6.5volt) for the different front and backs.
Would it be correct to replace the control timer To fix this issue? And why would it start flashing now after motor replacement? ( the motor installed by an experienced Diesel mechanic ) staying he doesn’t know” any and all good advise wanted please!!