deere 4115 no power to dash, wont start

gto7419 · Feb 13, 2021

Hey guys,

Having an issue with my 4115.

Initially the tractor would not start and the dash wouldn't light up. The second from the rear 10A fuse with White/Black wires was blown. After replacing it, tractor still would not start. At a quick glance at the electrical schematic I believed this to be leading from the light switch and pulled that connector. Im not so sure anymore. Either way, the tractor started right up. Fast forward a week and the fuse is not blowing and even with the fuse and connector pulled the tractor wont start. The fuse is connected to white/black wires. White/black to a fuse is not on the electrical schematic I have. I do not have the optional work lights. Anyone know what this fuse is for?

I have tested both the S2 Light switch and the S4 Turn signal switch. Both are behaving properly. These are not the issue.

Voltage at the Ignition switch drops from 12.7V to 2.7V when the key is turned to the ACC on position. I pulled both diodes (at the same time - yes I know) and one of them is bad. I have one on order. I believe these issues are related but also that I have an additional problem.

With diodes removed or installed I am STILL getting a voltage drop until I REMOVE the 15A fuse which is red/white. This leads to the headlights and the tail/turn, and the dash indicator on the control panel wiring harness. Seeing as I pulled all of the light switches, I did some tracing to figure out what was going on. I got zero resistance between this red/white and the white/black coming off of the ignition switch. This leads me to believe that this fuse leads to the K3 safety relay which is directly connected to those diodes. Why are the colors off? Any ideas here? Is the safety relay bad? Did the diode cause it to fail? Did the relay cause the diode to fail? Is the regulator bad? Any reasonable expertise here is appreciated. It is freezing cold outside and my hands are about to fall off. Some pinpointed help of where to take some measurements would help.

Anyone else have colors in their factory wiring that doesn't match the electrical schematic?

Thanks!

Roadworthy · Feb 14, 2021

I'd probably start at the beginning. Have the battery load tested. Be sure it has a full charge. Clean the terminals. Clean cable ends. Be sure you have a clean, solid ground connection. Consider that your starting point.

gto7419 · Feb 14, 2021

Battery is a month old and I put a jump pack on it when I saw the voltage drop. Still had a voltage drop. Checked the ground when I did the battery. I believe the voltage drop is related to the 15 amp circuit or the safety relay.

I have some led lights that are wired separately and fused off the battery. If I turn those on, when I turn the key to run, those lights turn off immediately. If I pull the 15 amp fuse, they stay on. That defies the bad ground idea a bit.

gto7419 · Feb 14, 2021

Run position is what I'm calling acc on. That's where I'm getting voltage drop. Did not test start position. Not enough hands.

I pasted the pages together. My factory colors don't all line up.

gto7419 · Feb 14, 2021

Then why does the voltage stay put when I remove the post ignition switch 15a fuse?

gto7419 · Feb 14, 2021

I'm under the assumption that I'm talking about f4 as well. Hmm, so you think it's not current draw but rather a weak connection leading to the ignition switch? This would make sense for not blowing the fuse or having a fire I guess.

gto7419 · Feb 14, 2021

Will check tomorrow as long as the weather holds up. Thank you for the help! It is much appreciated!

gto7419 · Feb 15, 2021

Crimp on the + wire from the batt to the starter was no good. Re-crimped and it runs. While I had just cleaned the connections on the ground a month ago, I replaced the entire wire with a heavier gauge and new crimps. Thank you guys and especially K7LN!!! Still can't figure out why my separately run leds turned off when key was turned to run. Should have been enough current/voltage for them to run - especially if no current was passing through the + wire to the factory electric.

I still have that diode on order and seeing as mine is bad, I will replace it when the new one comes in.