HUD works for a few seconds and then goes off.
 

Hello I have an 89 coupe with HUD nothing swapped it will come on when the key is turned to the on position and it stays on for a few seconds and then goes off, but i also dont have cluster lights i have swapped the tcu with a working one and the head lights didnt go up and down brake lights work, there is an aftermarket radio in the car, any suggestions? What would cause it to light up (tthe HUD)