JD 4100 Control Module Troubleshooting

[al3]

Break out the multi meter and check charging voltage and see if its significantly above spec. If so, the likely suspect components would be battery, rectifier, and or/all chassis grounds/contacts associated with all three. Clean all grounds/contacts and check again. If still high I'd try a battery swap with some other vehicle (temporary basis, make sure its fully charge before the swap). Check voltage again. If still high, take a close look at the rectifier; not sure if the shop manual has a test or not--sorry. Good luck.

How old is your battery?

 

[Ottsrx7]

Break out the multi meter and check charging voltage and see if its significantly above spec. If so, the likely suspect components would be battery, rectifier, and or/all chassis grounds/contacts associated with all three. Clean all grounds/contacts and check again. If still high I'd try a battery swap with some other vehicle (temporary basis, make sure its fully charge before the swap). Check voltage again. If still high, take a close look at the rectifier; not sure if the shop manual has a test or not--sorry. Good luck.

How old is your battery?

I checked voltage at idle and it was 12.05, at 2500 it was only 12.4 this seems low in comparison to vehicles. Do you know what it should be right off the alternator?

 

[Ottsrx7]

Battery is almost 4 years old

 

[jd110]

I would be sure to check the fuel shut off solenoid. If it is bad, it can burn out the module. One of the modules functions is to control it. Test across terminals as shown.

 

[jaydee325]

I checked voltage at idle and it was 12.05, at 2500 it was only 12.4 this seems low in comparison to vehicles. Do you know what it should be right off the alternator?

I'd pull the battery, fully charge it and then get it load tested. Once you know you have a good fully charged battery, only then can you do meaningful checks of the alternator output as well as other electrical checks.

 

[al3]

This is out of the 4110/4115 TM1984 shop manual. Don’t have access to the 4100 manual, so use your own judgement as to applicability.

Battery. Minimum charge is 12.4 VDC. Each battery cell specific gravity of 1.285, all cells within 50 point of each other at full charge at 80 degrees F

Regulated amp and voltage test. Run engine at high idle (2850 rpm). Battery voltage should read between 14.2 and 14.8 VDC. Minimum high idle amperage is 13.5. Manual illustration shows this being measured at the battery. Their test procedure uses a tool to put a slight drain on the battery to insure there is a demand condition; could probably replicate by cranking the tractor a tad (should the battery have a full charge)

Unregulated alternator. Measured at the output terminals of the alternator. Slow idle—32VAC (notice the switch to alternating current on your multimeter). Fast idle 50VAC. “…..at fast idle…..meter should read a minimum of 40 volts AC at 2850 RPM.

I’d be tempted to temporarily replace the battery with a known good one, say from one of my cars/ truck and measure regulated voltage output again to see if there’s any change. If you search, you’ll find a history of 4010---4115 of failing batteries causing problems. Eliminate it and grounding issues are the easiest route to start with.

 

[beenthere]

Battery is almost 4 years old

First thing I would do is put in a new battery.. 4 years on todays' batteries is about their lifetime.

 

[jd110]

Another thing that I have seen cause low charging voltage is a bad glow plug timer/relay. I have seen them stick on and the alternator can't keep up with the demand of full time glow plug engagement.

 

[Ottsrx7]

Thanks everyone for your responses. I will perform the tasks and tests suggested and update soon.

 

[Ottsrx7]

I couldn't wait so I did some tests awhile. The shut off solenoid is out of spec with the following readings: C to D - .15 ohms, C to E - 0.6 ohms, D to E - 1.1 Ohms. I also unhooked the alternator harness and tested the AC voltage at the connector. at idle I get 17VAC, at 2000 rpm I get 31VAC. not sure if this is normal or if the alternator is bad as well. It's worth mentioning that I also found some darkening (Just like in the pic I originally posted) on the clear plastic shield around the solenoid pigtail so this was definitely getting hot.

I have a digital battery tester which tells me the battery is good but it shows the SOC only being 65% after sitting on the 3amp/then trickle for a few days so I'll be replacing it. Should I test the voltage regulator and safety relays that seem to often be tied to electrical gremlins? IF so, does anyone have the specs for those components?

I was also curious if there is a general ohms test range for checking the ground cables?

Thanks again.... I feel like I'm finally getting somewhere!