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KOMATSU D20S STARTER PROBLEMS

rslawson

Active Member
Joined
Jul 10, 2016
Messages
28
Location
USA
Mr. Miller I think I have a bad starter motor as well as faulty solenoid. I have the starter and solenoid isolated from each other. When I test the starter motor with my meter I am reading continuity between the body of the starter and the stud bolt that comes up from the starter motor. It is ringing out and has 10 ohms resistance. On the solenoid I am reading resistance between the frame of the solenoid and the start terminal(the small screw terminal). The start terminal is ringing out as well and has 19.8 ohms. The start terminal and the starter motor stud on the solenoid are reading continuity between each other also. They ring out with 19.8 ohms also. Should I be reading continuity between any if these locations? I assumed I should not have anything on the start terminal of the solenoid until I turn the key to start it. If I try to jump the starter with a screwdriver it is creating a dead short and wants ti weld itself to the start terminal. If you would like any photos I would be happy to post them. Is my theory correct? My solenoid and starter motor are both bad thus creating a dead short when voltage is applied to either. Luckily the safety relay is working properly and is not allowing me to start it
 

rslawson

Active Member
Joined
Jul 10, 2016
Messages
28
Location
USA
The battery terminal in the solenoid is not ringing out. It appears to be isolated properly.
 

DMiller

Senior Member
Joined
Feb 21, 2010
Messages
16,430
Location
Hermann, Missouri
Occupation
Cheap "old" Geezer
Does the motor shaft rotate? With the motor free connect a set of pumpers to the motor stud and the case to a battery, if it arcs HARD the motor is shorted. Same goes for solenoid, if you can trigger it with a battery and the feed comes thru the main stud then is OK if does not pull in or pulls in and locks in then most likely bad.
 

rslawson

Active Member
Joined
Jul 10, 2016
Messages
28
Location
USA
I have tested both like you suggested and they both arc HARD. I will be replacing both of them again. Thank you for your help.
 

rslawson

Active Member
Joined
Jul 10, 2016
Messages
28
Location
USA
DMiller,
Since I last posted here I had a local mechanic come test the starter and it turns out it was bad. I have since bought a replacement starter( had it bench tested- works perfectly), bought 2 new batteries( had them bench tested- perfect). I put the new starter on the loader, I turned the key and it tried to start. Since it had been a while since I had it running I did not want to burn the starter up so I quit trying to start it. When I say it tried to start the engine turned over several times, smoke came out of the exhaust pipe, and you could hear it wanting to fire up. It was cold that day and like I said I did not want to burn up the new starter. I tried to start it again and the dang thing did just like the other one did.....made a click sound and nothing else. I took the starter back off the loader and had it bench tested again. Still perfect. I have put it back on the loader and nothing!!!!! I have verified I have voltage on the starter and I ran a dedicated wire from the neg battery post to the starter mounting bracket( just to ensure I have a good ground). Nothing. What am I missing? Why is it doing this? I mean it tried to start and now nothing!. I am at the point now where I want to install a new ignition switch and run it to the starter. Can I install a 24V push button that applies 24V directly to the starter, push the button, once it starts stop sending the 24V to the starter? Will that cause any harm to the starter? If I unhook the relay switch and install the push button that will not hurt anything will it? I am at a loss. I hope this makes sense and I apolgize for the long explanation but I wanted to give all the information I could think of.
 

DMiller

Senior Member
Joined
Feb 21, 2010
Messages
16,430
Location
Hermann, Missouri
Occupation
Cheap "old" Geezer
You want to keep the load off the start button, they use a smaller low load solenoid to energize the larger one, check that it gets dash switch power when directed to.
 

Krackerjack9

Well-Known Member
Joined
Dec 3, 2007
Messages
170
Location
working at Camp Anaconda,Iraq
Occupation
working in Iraq right now
is your glow plugs working, the glow plug wire on mine burned out once i replaced it turn the key to the left for about 8 seconds then turn to the right bam fires right up
 

mitch504

Senior Member
Joined
Feb 27, 2010
Messages
5,776
Location
Andrews SC
Since this was 3 years ago, he has probably scrapped it if he couldn't fix it! :D Yeah, I'm a smart@ss, I can't help it, since I don't try.
 
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