i have a 2000 7.3L stock and have to have it smog (thnx California ) and i have codes p1391 p1393. would it be more likely that the glow plug relay is out, and if so how could i test it real quick to find out?? thanks...

 

Clear the codes, then test to see if they come back. But yes, most likely, the GP relay is to blame. To test it, I'd get a voltometer, and test to see if you're getting voltage across the big lugs when the key is turned on.

 

i checked the voltage on my glow plug relay and i had 12.6. any idea on what i should do next would help out alot....

 

Did you have it on both sides?? Just checking, but with the key off, one lug should be hot, and the other not. Then when the key comes on, both should be hot.

 

i checked it and one lug was hot with the key off but when i turned the key on there was still only one lug that was hot. Would that mean its probably the relay? is there any way to test just the relay to be sure??

 

That is the way you test the relay... If there's no power going to the big lug, then there's no glow plugs...