Well, I got a little time at home over the holidays. As a result of the very helpful knowledge passed to me in this group, I found the following problems with my rig:

• Slightly loose glow plug connector allowing moisture to cause corrosion inside the connector. Soaked with baking soda and water blew out with air.
• One bad battery with green light still light. Just for a test I was going to install my rv batteries and when one battery was disconnected, the engine compartment light went very dim. Replaced with Napa Omega's, spins like a banshee.
• Bad gpr "number 4!!!" This one was just replaced 5 weeks ago. It works most of the time, but then out of the blue stops working most of the time. Contactors are probably binding inside the relay. I paid dealer price for the first one and they have all failed in less than one year or twelve thousand miles. Apparently ford would rather keep giving me cheap new ones than one good one. Anyone know where I can get a heavy-duty gpr that may last more than 1 to 6 months? At this point I'm getting tired of replacing it.

I'm probably not the best at explaining this test, but I want to give a little back to the group. The test purpose is to determine if the gpr is bad or if it is not being signaled to close by the controller.

A very basic high water test for the 1999 psd gpr relay: Turn on the key and measure the voltage on the small wire towards the front of the gpr, should have battery voltage. Then measure small wire to the back of the relay, if the controller has signaled it to close, it will be somewhere near 0 vdc until the controler disengages it, then it will be battery voltage. (seems ford switches the ground instead of power) While there is no voltage on the back pin you should be able to read battery voltage on the large wire to the right of the gpr. If you don't read battery there, remove the cover on the large wire to left side of the relay and measure there. If you have battery voltage there, your relay is likely bad.

One thing to note, the glow plugs should be connected durring this test. This is due to the fact that a poor connection inside the relay will pass very small amounts of current that will read as battery, but could never heat the plugs. With the plugs connected, they will draw down that small voltage/current to almost nothing.