Well, here it goes, I turn the key on, all lights come on normal. The glow plug light goes out in a few seconds. When I turn the key, it draws on the battery (does not turn over), then "service throttle soon" light, and battery light start flashing. The glow plug relay and relays behind the glove start clicking back and forth, somtimes it stops on in own. If I try to start if again, it repeats the same thing. I followed the service manual and the glow plugs and glow plug relay all checks out. What is the voltage on the glow plug side of the relay? Please give me some directions to go, thanks.

HI TC welcome to the site, look at the troubleshooting guide in link below my signature, for the basics, if those don't work report back testing/results thus far. Also take a minute to update your signature with truck details

Been watching the sight for a little while, finally took the time to sign up. Thanks for the info. I'm going to check the starter today.

Battery connections and starter connections seem like the place to start looking for a bad connection.

Well, starter was not in great shape, so I installed a new one. Charged and cleaned post on batteries. When I turn the key, does not turn over. The glow plug relay is clicking about once per second, alternating with a relay in the dash, behind the glove box. The "Service Throttle Soon" light flashes with the battery light. Is the glow plug relay tied into the starter system? Why is the starter not getting power? Thanks for any help you may have.

Maybe the power isn't making it to the starter itself. The battery connections are a notrious spot for failure.

If you have a second set of hands around, take a measurement of the battery voltage while in "start." A drastic drop on the battery post may indicate battery is shot too. Have load tested if needed.