P1643 GMC -

Question

i changed my dashboard on my 1998 gmc c3500 hd and the glow plug light will not come on or it will not start

Answer 1

P1643 Wait to start igntion lamp circuit

This code will not cause the engine not to start. What you can do is check to see if any fuse opened, In the engine fuse relay box ENG 1 see if that opened.