John Deere 2520 died, won't start

[Captain Dunsel]

OK, happily closing the loop (again) on a dead 2011 JD 2520 Compact electrical problem. The culprit turned out to be rust under the bolt holding the negative ground cable to the frame. The cable end looked 100% clean, shiny, and normal where it bolted to the frame but it was rusted under the attachment bolt head. I sanded off the cable end and the underside of the bolt head and just like that it's fixed. Seems obvious once I found it but remember, I had voltage at the switch, the fuse box, and the starter so there was no reason to think anything was wrong with the battery cables. There was also no visible corrosion anywhere. So it looks like nominal voltage could pass thru the rusty connection and be read on a multi-meter at the start switch, starter, and fuse box but once a load was applied, the rusty connection was unable provide any amps at all. I read up on this a bit and the electrical guys call it constriction resistance. Anyway, the tractor is back to work and I'm happy. Posting this info in hopes of helping the next guy. Thanks to everyone for the input.

 

[CoyPatton]

Glad you got it going!
Battery cable connections (all 4) are the first check. 2nd is battery—have it load tested.

 

[jd2210newbie]

OK, happily closing the loop (again) on a dead 2011 JD 2520 Compact electrical problem. The culprit turned out to be rust under the bolt holding the negative ground cable to the frame. The cable end looked 100% clean, shiny, and normal where it bolted to the frame but it was rusted under the attachment bolt head. I sanded off the cable end and the underside of the bolt head and just like that it's fixed. Seems obvious once I found it but remember, I had voltage at the switch, the fuse box, and the starter so there was no reason to think anything was wrong with the battery cables. There was also no visible corrosion anywhere. So it looks like nominal voltage could pass thru the rusty connection and be read on a multi-meter at the start switch, starter, and fuse box but once a load was applied, the rusty connection was unable provide any amps at all. I read up on this a bit and the electrical guys call it constriction resistance. Anyway, the tractor is back to work and I'm happy. Posting this info in hopes of helping the next guy. Thanks to everyone for the input.

Yes, its called ohms law. V=I x R, so if you have some resistance if the load current, I, is very small then the voltage drop across that poor connection, R, is very low. So under a low load your multimeter will show full voltage. As soon as you turn on something, light bulb, starter etc, the voltage drop across R is very high and voltage measured on other end is very low.

Its kinda like connecting a small pipe to a huge pipe. As long is water is not flowing the pressure at the end of the small pipe is high, but once water starts flowing pressure will drop at end of small pipe.

As I mentioned in order to make my starter run at max speed I ran a separate heavy cable from - of battery over to the starter bolt that attaches starter to motor.

 

[Williy]

Wonder how many people test their cables with a volt/ohm
meter because if they get corroded could eat the center of
the cable and then you have two pieces of cable instead of
one! As fuses go I always test with meter looks can be
deceiving!
anyone hear anything about the 10 days no power or internet???


willy

 

[jd2210newbie]

Wonder how many people test their cables with a volt/ohm
meter because if they get corroded could eat the center of
the cable and then you have two pieces of cable instead of
one! As fuses go I always test with meter looks can be
deceiving!
anyone hear anything about the 10 days no power or internet???


willy

You can find gross problems with a volt/ohm meter like totally open circuit, but lets assume you have just a poor connection of .05 ohms which most meters can't measure. Assume 200A starting current and you get .05x200=10 volts drop in that connection and your starter will only click if you are lucky since it only gets 2 volts.

Marine stuff is even worse, unless you have very good cables the salt water travels down the wire under the insulation until it corrodes the wires.

 

[CoyPatton]

You can find gross problems with a volt/ohm meter like totally open circuit, but lets assume you have just a poor connection of .05 ohms which most meters can't measure. Assume 200A starting current and you get .05x200=10 volts drop in that connection and your starter will only click if you are lucky since it only gets 2 volts.

Marine stuff is even worse, unless you have very good cables the salt water travels down the wire under the insulation until it corrodes the wires.

This a great reason to get a meter that reads dc amps. If the amps are not present through the cable, but are present at the battery, you have found it answer. Unfortunately this is not a common feature on meters.

 

[Williy]

AT AMAZON​

UNI-T UT204R Digital Clamp Meter, Auto Ranging TRMS 6000 Counts NCV Volt Amp Meter with AC/DC Ohm Diode Capacitance Resistance Temperature Frequency Continuity Test $61.28

willy