Occasionally my truck will not start. Everything seems be working fine when I turn the key to allow the glow plug heat but if the glow plug indicator light does not come on it will not crank nothing. Any suggestions?

SP

 

It is difficult to offer anything without having some idea of the maintenance history.
Something like battery connections, which are routine maintenance items, could be responsible.
There is a glow plug module and relay that are part of the system and they could be checked .