glow plug issue on JD 4100

[flipppper]

I thought that I saw a discussion on this before, but can't find it now, but I'm not sure where to start with finding the problem with cold weather starting on my 4100. It starts like a dream until under 50 degrees, or if I plug it in for a few minutes. I'm sure that the problem is likely the glow plug (s). but don't know where to find them, or how to tell which glow plug(s) are bad. And I read something about a glow plug controller? Could this be my problem? Any advise on where to start?

 

[George2615]

Welcome to TBN.......................

According to this Deere site you have 3 glow plugs. They are on top of the engine (item# 28) and have a wire connecting them all. You need to test them first before replacing to see if the plugs are bad or if the timer supplying power to them is at fault.
To test them, disconnect your battery first, then disconnect the wire going to each plug. Then using an ohm meter measure the resistance of each plug between the top terminal where the wire was and ground. You should measure a resistance of about 3-5 ohms. If you get no change in reading the plug has an open circuit or if it reads 0 it is shorted to ground. In both cases the plug it bad.
If they test good, reconnect the wire to each plug and the battery. Then using a DC volt meter connect the red lead to the terminal on the plug where the wire is and the black lead to ground. Turn on your key to glow plug position and you should briefly read voltage of approx. 10-12V. If no voltage is read the timer / controller could be bad.

Glow plugs
John Deere Glow Plug

Glow plug timer can be found in the electrical section of this link.

 

[DFB]

The glow plugs can also be manually activated on these early JD 4100's independent of the timer. You could also try this for a quick check...engage the dash PTO switch and then hold key in start position for several seconds. Disengage PTO switch then start again, If you easily start chances are the glow plugs are still good and the timer failed. If there's no change then follow the instruction outlined by George 2615 in the prior post to check the condition of the glow plugs.

A timer failure can cause other problems too most noticeably a lack of charging at the battery. That is what happened when my timer failed.

What was happening I eventually found out was that current was being applied continually to the glow plugs circuit thru the failed timer (contacts didn't open after the timed interval) and the alternator could not keep up with the continuous current flow and eventually the battery would become discharged enough that the tractor would shutdown

So I just unplugged the wire harness going to the timer module and all was good again (charging correctly) I haven't replaced the timer since and just use the manual override now.

 

[joecdeere]

shoot me your email and I'll send you a PDF of the tech manual, all the test and wiring are in it

Joe

 

[flipppper]

ah thank you guys, now things are starting to make sense, as I suspiciously have recently also developed a charging issue just like you outlined. I'll let you know what I find

 

[flipppper]

Apparently I need 5 posts in order to share my email., Joe, maybe I can put it in my profile.

 

[jimmysisson]

Well to up your post count you could say what a "blind vending operator" does?
Jim

 

[JimLAllen]

The glow plugs can also be manually activated on these early JD 4100's independent of the timer. You could also try this for a quick check...engage the dash PTO switch and then hold key in start position for several seconds. Disengage PTO switch then start again, If you easily start chances are the glow plugs are still good and the timer failed. If there's no change then follow the instruction outlined by George 2615 in the prior post to check the condition of the glow plugs.

A timer failure can cause other problems too most noticeably a lack of charging at the battery. That is what happened when my timer failed.

What was happening I eventually found out was that current was being applied continually to the glow plugs circuit thru the failed timer (contacts didn't open after the timed interval) and the alternator could not keep up with the continuous current flow and eventually the battery would become discharged enough that the tractor would shutdown

So I just unplugged the wire harness going to the timer module and all was good again (charging correctly) I haven't replaced the timer since and just use the manual override now.

"Would a bad timer also cause the charge/discharge light to remain on ? I have 14.8 V at battery all the time."