My dad converted a friend's 84 e-250 to the newer glow plug controller. He mounted it in the same location as the newer ones mount. It appears to be wired up correctly but it will only light the wait to start for a second or two and then the relay continually clicks on and off. He checked all the glow plugs with the test light trick and replaced one bad one. Am i missing something or is there still a weak plug? I always thought when they did that it was due to a bad plug or two. I suggested he replace all 8 with new ones but he disagreed. Any advise would be great.

 

Maybe he better check them again with an ohmmeter to double check. The light method always works for me, but you never know.

 

on the occasion it shorts to ground, the light will lie to you, use a meter to be sure.

 

I will check them all with a meter. Is the spec 2 ohm?

 

I believe so, check this forum, there is a thread almost identical to this one, hard starting problem