I put in all new glow plugs and straps, When I turn the key WITHOUT glow plug wire connected I get +12 vdc at glow plug terminal. When I connect glow plug feed wire to terminal and turn key I get 0 vdc. I checked the 175 amp fuse, good. At this point after hours of work Im confused, what is wrong. I have the schematics. What can I check next, sway air intake relay with glow plug relay ??
I have a 2004 2500HD 6.6 Vin1 deisel. any help greatly appreciated, is there a How to check glow plug relay step by step, I took mine out, tested on bench and got voltage to both air intake and glow plug terminals on controller.
thanks all
MGM

 

Probably relay contacts burnt or burnt connection somewhere between fuse,relay or glow plugs. If you can access the relay easily, with glow plugs connected, take a voltmeter and put one lead at the line side of the relay, the other lead at the load side of the relay. With the glowplugs activated, you should get 0 volts, if you get 12 volts, then most likely the relay contact is burnt. If you get 0 volts, take one lead from the load side of the relay, the other lead to the glow plugs, if you get 12 volts, then you have a bad connection between the relay and the glow plugs.