Glow plug relay question

[Baer]

One more relay question: A few weeks ago I drove home listening to a "clunk" noise on the fire wall. The next morning SURPRISE she would not start. I just got around to putting a volt meter on it and found with the ignition off I got no reading between the orange wire terminal and ground but a good healthy 14 volts with the ignition in the on position. I also got a loud "clunk" from the relay every 1 to 2 seconds. I plan on changing out the glow plugs but in addition am I needing to change the relay or circuit board?

 

[cpf240]

Follow the GP system troubleshooting section of the -20 TM. My guess would be that some, or all, of the GPs are bad, or perhaps a bad temp sensor is causing it to cycle the GPs more than needed.