I recently replaced my faulty Autolite plugs on my 7.3.
WTS light used to come on for 3 sec then relay started to click. Never let it click and see how soon it will stop though.
No clicking after I put a brand new set of ZD-9.

 

Since there is a problem after water spill I'd first pull the cover off the controller, blow it dry with compressed air, disconnect and clean all wires and reconnect back with dielectric grease before throwing new parts at it. Your volt meter gauge should be fine, don't see the reason pulling the dash apart.
In my opinion that controller is simply in a wrong place from the factory. I used to own a few '80s Volvo and Mercedes diesels and have never seen any problem with glow plug controllers.

 

the clicking after the WTS goes out is the relay doing an after burn, abd is normal. some have loud relays, some do not.
my 88 and the 91 are very loud.
the 2 89's the 2 90's, and the 92 were silent.

 

Thanks everybody. It turns out that the relay went bad at the controller. I'm putting one off a parts truck.I tester all the plugs with a test light and all lit up. I found some oil in the intake so I've been trying to find a new cdr valve for a decent price. I ordered a kit with a new grommet and vent tube for 80$ on ebay.

 

that is the prime reason i always recommend that people put a LED or small light bulb connected to the output of the glow plug relay. the wait to start light tells you if the controller is working, not if the glow plug relay is working.
by having a light off the output of the glow plug relay if the glow plugs are getting power, the added light will light up if the glow plugs are not getting power, it will be off.

 

Thanks for your input Tom, that really clears things up. I've switched relays in the past and didn't think much of quiet vs clicking since everything still works fine. After reading other's posts and then yours I fired up my pickup. Turns out my relay is silent and I never noticed or cared.
The light suggestion is good too, especially for us with the quiet relay.

OP: glad you got it figured out! Pretty odd that the engine started like normal even though the relay died...never would have thought that.

 

another thing people don't realize Josh, is that their controller nay very well be doing the after burn thing, but they do not hear it because the engine is running and louder than the relay cycling.

 

Could be a bad harness or controller. Mine clicks with 8 new plugs. Guy in the video is a moron.

As the plugs warm up, the resistance goes down, if the resistance is too low (one or multiple bad plugs or connections) the controller will think the plugs are already hot, limiting juice to the remaining GPs, which would keep 5 plugs from getting juice for all eight, so as to not burn them out.