The factory relay on my Max 22 wouldn't light the glowplugs. I don't now if the relay failed or a temp sensor went bad or what. If I jumped the relay terminals they would light. I tried to get a wiring diagram to chase down the problem but didn't have and luck. A new relay cost over a hundred bucks and I didn't want to spend that much on a "guess" so I just rewired the glowplugs using a Ford starter solenoid and a waterproof push button on the dash. Removed the factory relay and I used a couple of electrical terminals to connect in the new solenoid to the factory wiring. Didn't have to cut any factory wiring. Works great. I push the button and count to 5, then start it. Cost me 15 bucks.