i have a 1993 w250 and i was putting a tach in it and hen i was done the truck was running fine. i turned the truck off an went to turn it back on and it wouldnt even crank over. all i get is the grids warming and i turn the key and nothing happens. the battery is brand new and i have checked all the fuses and relays and all of them are still good. i dont know what i did but i need help. this thing is my daily driver!!! i would appreciate any help. thanks. mayne something with ignition wiring???

 

sounds like your starter or relay went belly up. Just coincidence I think. Does it click at all? Is it a man or auto?

 

try jumping the little wire (ignition wire) to the big wire (12v +) and see if you get any jump on it. if not, you probably fried the starter, if you get a jump, than you wired something wrong

 

Make sure to look over all the fused links too. I had this happen and it took some looking, but I found a little black spot on the insulation of one, stripped it back and it was toast inside. Just a thought, good luck.

 

You can run a wire from the solenoid - small connection on top of the starter - touch it to the positive post on the battery to test the stsrter. If it cranks you have a problem somewhere elce. Just make sure if it's an auto it's in park and if it's a manual it's in neutral. Follow these checks and turn the key to the run position and see if it starts.

Bob

 

Had the same thing happen once, the pink or red and brown wires coming off the positive terminal one of the was wore in half. Whichever one goes to the starter.