ZD28 Glow Plug Relay Location?

[BrianF8]

I have a ZD28 and I'm not getting voltage to my glow plugs. I was having rough starts in cool weather but fires up great when warm.

The glow plug lamp lights up so I want to try to troubleshoot the relay before going after the controller. Does anyone know where the glow plug relay is on a ZD28?

 

[lugbolt]

It ain't got no relay on the glow system.

Do a voltage drop test on the circuit beginning from battery to slow-blow to key switch, all the way back to the glow plugs; under a load (key in glow position). Use your wiring diagram and follow the circuit. Pretty simple system once you learn how it works and study the wiring diagram.