CK30 Preheater controller

[Steve_Miller]

Anyone know what exactly the preheater controller does? Does it control another relay that actually powers the glow plugs for a predetermined time? Having trouble with this circuit, I have no glow plugs at the moment (starting with my heatgun shoved in the air intake). I've tapped (aggressively) on the controller box and it fired the glow plugs and started once but haven't got it to do that again. Glow plugs are fine, light on dash comes on like it is timing. I'm out of warranty so I'm trying to troubleshoot on my own. I have the copy of the service manual that someone provided online here a year or to back but it is not exactly the same layout on the firewall as mine. Any help would be greatly appreciated.

Thanks
Steve

 

[SSdoxie]

This is how it works on the Bobcat verison. I presume it is the same.
The preheat controller is a timer. It sends a signal, which passes through a fuse, to activate the glow plug relay. The output from the relay sends voltage to the glow plugs but also lights the indicator light in the dash. If the glow plug indicator light is coming on the relay is working.

 

[DK35vince]

If the glow plug indicator light is coming on the relay is working.

Mine didn't.
The glow indicator plug light would come on in the dash of my DK 35, but I had no power to the glow plugs.
My preheat controler was bad. I replaced it with a new one and its been fine ever since.

 

[SSdoxie]

Mine didn't.
The glow indicator plug light would come on in the dash of my DK 35, but I had no power to the glow plugs.
My preheat controler was bad. I replaced it with a new one and its been fine ever since.

I know Bobcat had quite a few design changes made in the electrical system, this must be another one of those. The Bobcat feeds the indicator light after the relay.

 

[Steve_Miller]

Thanks guys

Steve

 

[Steve_Miller]

My glow plug relay is bad, i can tap on it and it will work for a time or two then stop working again. It energizes but does not make contact closure to the plugs. My preheat controller controls the glow plug relay. If the coolant sensor in the engine block is above 30 degrees (Celsius) the glow plug relay and light will not come on. If the temp is below that they both energize (two separate outputs from the controller).

Steve