Glow Plug Relay

[tractorman21]

What's the proper way to check the glow plug relay? 1997 Superduty has been starting hard lately and i was told to check the glow plug relay.I was instructed to check the two large post for voltage.I was told one stays hot(12 volts all the time) and the other should show 12 volts when the key is turned on.I checked the relay and only 1 side showed 12 volts.with,or without the key being on.I replaced the relay and the new is doing the same thing.Only showing 12 volts on 1 side of the relay.What else could be wrong? Could the new relay be wrong for that application? It's aftermarket,not a ford product.
Any thoughts,or opinions will be greatly appreciated.

 

[JLDickmon]

http://www.superdutydiesel.com/forums/911-diesel-down/23955-missing-no-power.html

pick this up on page 6..
post 50 something...

 

[Patrick Feeley]

When the glowplugs are active (you have about 1.5 minutes after turning the key to Wait-To-Start ... ignore the WTS light as it has nothing to do with how long the plugs are actually on), measure the voltage between the two big terminals on the relay (one probe on one big post and one probe on the other) using a digital volt ohm meter (DVOM). Anything greater than 0.3V and you need a new relay. A lot of folks, including me, like the Stancor 586-902 relay (available from NewarkInOne or Allied Electronics ... they call it a DC Contactor). Cheers!