No power at glow plug when connected

[jdice]

Hi,
My old L245DT won't start. It has no power when I turn the key. I've checked the obvious things like the battery, power to the starter, power to the key switch, power to the starter switch etc. This stuff all checks out. I do not have any power on the dash lights. The glow plug indicator does not glow however I traced the power down to the first glow plug. When I remove the wire from the glow plug I have 12v when turning the starter switch counter clockwise (to fire up the glow plugs) but if I put the wire back on the glow plug I don't get any power at all. It seems to me like the glow plug isn't grounded?? Is this possible? Should I be able to see 12v on my ohm meter when the wire is attached?

Also - I pulled the first two glow plugs out and bench tested them. They show around 30 ohms of resistance and they glow bright orange when I hook a 12v battery directly to them. I didn't pull the third one yet because it's harder to get to.

Thanks,
Josh

 

[gkirby]

I had a similar problem with my L2900 tractor. Try disconnecting the copper strip which connects to the top of the 3 glow plugs. Take steel wool or light sandpaper and go over it until it shines like a new penny. Also do the top connector on the glow plugs. Replace it and see if that solved the problem. It did for me.
Good Luck,
Gene

 

[jdice]

Thanks for the advice Gene. I'll give it a try and post back.

Josh

 

[lsmurphy]

From what I have read and understand all three must glow to complete the circuit. IOWs if one does not work, none of them work.

Sounds like #3 is bad.

 

[gpreuss]

To me this sounds like a poor connection. You should read 12V where the wire hits the glow plug. If you have it when the wire is lifted, but it goes away when you touch the wire to the glow plug, you probably have a poor connection somewhere upstream; probably at the switch.
You can run a wire straight from the battery to the glow plug to confirm this.

 

[birddogger]

I'd start with cleaning and tightening the 4 ends of the 2 battery cables.
Check for swelling at the battery ends of the cables; swelling of the sheath indicates internal corrosion of the copper conduction, it will read some voltage but will not carry current enough to light the dash lights.
That or the old battery is dead and only has a surface charge, that also will indicate OK on a volt-meter but can't light a lamp.

 

[South 40]

Check the fuses and have a really good look at the preheater coil, I have seen many fuses that looked good and tested good, but once you put a load on them they heat and open, thus no current, same thing with the lil coil for preheating, it could look fine but seperate and open when under load.

A broken wire or poor connection somewhere in the system could also show voltage but not allow enough current to make everything work.

Many times a poor ground in the system can turn out to be the problem, a prime example is trailer lights, they will do all kinds of goofy stuff without a good ground.

Does it crank over but won't start because of the glowplugs or will it not even turn over?

Not cranking could indicate and bad ignition switch.

Best Regards

Paul

 

[jdice]

Thank's for all of the advice! I've tried cleaning up the glow plugs and wires that connect them. I've ordered a new started switch after talking to the tech at B&G Equip. I'll post next weekend after I replace it.

Josh