Hey guys, let me run this past you. I just purchased my first 7.3 IDI 1988 F-250. The seller told me that to crank the truck, you have to leave it plugged in for 30-45 minutes. I've noticed that the WTS light does not come on at all. So I searched through the forums (which have been a great help) and learned how to manually ground the g/p controller. Here's what's happening:
Whether the truck is plugged in or not, the controller seems to click on/off really fast as soon as I turn the key on. It does this only once, not multiple times. But, the WTS light is not comming on. If I manually ground the controller with a jumper, the controller will click on when grounded, off when I remove the ground, but still no WTS light. However the truck cranks right up. I'm sure the glow plugs have never worked during the time that the previous guy owned the truck. Any ideas? Is the controller bad, do I have wiring problems, or just multiple inop glow plugs? Thanks in advance guys!

 

I forgot to mention that I've already replaced the bulb on the WTS light.

 

There is a 2 prong black plug there with the controller,make sure its clean/connected,that is the wts light.All this is if you have the solid state system.
You may want to check all the gp's,take a test light,clamp to pos batt post,pull wire off gp,touch probe to where you removed the wire,if light lights,its good,no light,no good.Bad gp's will make the wts way too fast.Use only beru/motorcraft gp's.

 

I've got a set of motorcraft g/p's and I might put them in first to see what happens.

 

You might want to check the fuses.Might have one blowen.
Just a thougt...

 

Hey

My 88 F350 is in good working order and when my WTS light started to be quick like that it was the glow plugs. They are starting to fail. In your case I would suggest replacing glow plugs.

Good luck

 

Make sure you use anti seize and watch the torque.

 

sounds like its bad gp's you can test them with a test lite but i think i'd just replace all of them since it atarts up if plugged in.

 

The problem is fixed! I replaced all the glow plugs with motorcraft and had to replace to g/p controller. It works perfectly. Thanks guys for all your help.