are you using a chevy truck or a dodge truck like in your sig. if its a dodge you dont have glowplugs. but if your referring to a chevy let me and ill try and help. just a little confused as to what your asking about. a little more details and ill try and help you out
are you sure the glow plugs arent working or are you assuming theyre not working because the light wont turn on.
if your not sure whether or not theyre working id do as woody said and check the relay. and just for the sake of stupid things happening and over diagnosing, have you checked the bulb itself on the glow plug indicator? theres a chance it couldve gone bad. if all your fuses relays and bulbs are good, it would start to think either a bad wire somewhere or a computer problem
well first off it wont start so unless i put the ether to her so i know my gp's aint heating. idk how the best way to get to the bulb for the light to check it. how can i test the relay? would turnin the key on and puttin a test light on the out goin wires work? i used jumped a wire across the two wires comin off the relay the other day and it had power cause it arched off. wat can i check. i dnt wana keep startin my truck on ether.
check power inlet to power outlet powe.then if thats good check power in let to each wire plug where the harness is pluged into the glow plug relay.. if any are bad then the relay is bad.. i skiped it all and just replaced the damn thing its only like 70 bucks.