I have a rtv x900 diesel I use on my farm. I believed the glow plugs were not working. I tested them and had resistance on all three. Checked my fuses and all are good. I was going to replace the plugs anyway, but my dealer said they seldom have the glow plugs go bad. Instead, they said there is a relay or “timer” that is the usual culprit. Does anyone have experience with this? Thank you.