JD 525 Electrical Issues

PeteA · Jun 22, 2014

Well....I pulled a real boner. In a hurry and not paying attention, I installed a new battery in my John Deere F525 mower. It wasn't until I tried to start it and blew 3 fuses that I noticed that the positive and ground posts on the new battery were reversed. In other words, I hooked the positive cable to the ground post and ground cable to the positive post.

After replacing the said blown fuses several times, I have no idea what's wrong with this thing. To start the JD F525, the brake must be pushed down, and it appears that the problem is somewhere after that circuit.

If I turn the key on, the lights come on the dash, everything is fine at this point. But when I push the brake in to start it, the fuses blow. I originally thought something happened to the brake switch when I reversed the battery cables but after taking the brake switch off and checking it with a continuity tester via the service manual it is o.k.

There are several relays and who knows what, that are next in line after the brake switch. Wiring issues are not my expertise. Are there any Techs out there willing to get me pointed in the right direction in diagnosing the problem?

Thanks in advance.

RetiredCarGuy · Jun 23, 2014

Is there any odor? Discoration of components? Wiring and connectors to be checked also. Check the relay and circuit board for odor and color change. If relays are easily unplugged, remove and do the same.

Also a question, did you attempt to start the motor on the reverse polarity battery? Or, you just switched ignition on and it failed?

PeteA · Jun 23, 2014

RetiredCarGuy,
I did not notice any odor. I will try and check connectors tomorrow.

On the JD525 the brake must be pushed in first, which opens a relay to allow power to continue through, so I didn't have a chance to try and start it as the fuses blew as soon as I pushed the brake in.

I will post what I find , if anything, tomorrow.

Thanks!

PeteA · Jun 27, 2014

Well....after 5 days of being aggravated with myself for doing such a stupid thing, I finally got her running. Hopefully the following hard learned information will help someone that may find themselves in the same situation.

I went down to my local John Deere dealer and was fortunate enough to be able to talk to the head mechanic about what may have happened by hooking the battery up backwards. Thankfully, he didn't look at me and say "what a bonehead". After looking at the wiring schematic in the shop manual he suggested that it was probably one or several of the diodes that got fried. For those of you that don't know what a diode is (I didn't), it allows current to go in only one direction. Interesting! To check a diode, you would simply unplug it and with a continuity tester make sure current will only flow in one direction. If current flows in both directions, then the diode is faulty. On the JD 510/525 models, there are 4 diodes. Two were good but the other two were bad. I replaced the two bad diodes at 6 bucks a piece and I was off and running.

RetiredCarGuy · Jun 29, 2014

Glad to hear that it was a simple and low cost repair. Besides that John Deere built in this safety for a reverse current condition. Great engineering by John Deere!

PeteA · Jun 30, 2014

Yes, indeed! This could easily have become a nightmare with having to possibly replace a wiring harness, multiple relays, ignition switch etc, etc...

frantic · Jul 5, 2014

My John Deere F525 Lawn Tractor PTO starts then after cutting two or three passes drops off and will not start back up ?

bass78 · Aug 5, 2014

can anyone give me some info on a john deere f525 needing to know how the safety switches are wired. having a problem with the pto heating up and blowing fuse for pto and idea?