i tested relay for glow plugs and got zero volts with ignition off i then followed what should be the hot wire on glow plug relay to the Truck starter relay and see that it is not on the what appears to be the hot side. This is my buddys truck could someone have switched this wire on him? I get no power on this connection at the glow plug relay. I disconnected it from the the glow plug relay and still get zero. While disconnecting the relay it was corroded so it broke taking nuts off out of the relay will have a new one in moring. Is the relay for glow plug and the one for truck same part number. Again this is a 1992 f350, 7.3. No power at relay has me confused. Thanks for any help.

I was looking for 12 vlots at glow plug relay with ignition off and found zero

Once i disconnected relay i check for power again and still zero.

when i tried with ignition on i heard relay click on for about 30 seconds and then click again.

David

 

You can look back at glow plug or hard starting posts Dave S has posted pictures in a lot of them explaining what each wire does.

 

dbrigger,
Welcome to FTE and the IDI diesel forum.

Here it is.




On the 92 the glow plug power wire should be on the same terminal of the starter relay as the battery power wire is.

Constant battery power on the battery terminal of the relay.

Since you said the relay was clicking, evidently the ignition wire has power when the key is on and the ground wire has a good connection.


While you are checking things, near the dip stick is a connector where the engine harness plugs into the chassis harness.
On the side with the large guage wires (probably yellow wires) look to see if the connector looks like it has been hot.
If it does, you need to splice the two large wires aroung the connector.
Those are the glow plug power supply wires, common for the connector to overheat when they get older, which causes a drop in amperage supplied to the glow plugs.

 

thanks for the help you were right on, i will check those yellow wires also. it appears that the last guy who worked on the truck put the relay power wire on the wrong starter relay.

Thanks again