I got an e-mail from a reader. I post this with his permission:

From: Larry
Subject: Kubota L1500
Date: December 30, 2006 6:57:33 AM PST
To: ironcross11-at-earthlink.net

Just read your articles regarding hard starting on some model Kubota tractors. I have a Kubota L1500 (same as the L175) and have always had problems starting the engine. Starter has been rebuilt, new battery installed but starting it in cold weather is impossible. I seem to have good compression and the engine does puff white unburned smoke when cranking the engine. I'm not sure what amperage the glow plug circuit should supply to the glow plugs, so I haven't tried reading it. Do you have some knowledge of the glow plug circuit that you could pass it on to me? I do see the indicator coil on the dash begin to glow when activating the glow plugs but don't know what it goes through after this on it's way to the glow plugs. I would appreciate any info you could give me.
Thanks,
Larry

From: Mike
Subject: Re: Kubota L1500
Date: December 30, 2006 6:57:33 AM PST
To: ironcross11-at-earthlink.net

If it's like mine, power should go from the Key switch to the heating switch to the indicator coil to a big coil resistor (under the battery on mine)and then to the glow plugs. It's all a series circuit so if any part isn't working, none of it should work unless you have a short. Here is the schematic from my cheesy reprint manual.

The check for a short is easy. Without disturbing anything else, very carefully disconnect the second glow plug in the circuit from the ground. If it the glow indicator still lights--you have electric shorts!

If it doesn't glow, have an assistant close the glow plug heater switch and then rattle the wiring harness around (in a dimly lit area) and look for sparks or jumps on the ammeter (if so equipped).

Mike

posted by ironcross11 at 1:56 PM