Massey Ferguson 135 - Electrical Mess

Hey guys,

I just recently purchased my first tractor, a Massey Ferguson 135 Perkins Diesel! The tractor is in great shape for its age, fires right up and runs great.

The issue I have is in some custom electrical changes that have been made by people over the years. For example, there is no key or even ignition switch for the tractor, just a push button starter. Almost all of the gushes are not functioning, because most of the wiring for connections is unplugged or removed from under the dash.

While I d like to get everything back to working order the first two things I d like to address are, ensuring my charging system is charging my battery, it doesn t seem to be at the moment. Second, reconnecting my fuel gauge and sending unit.

Have any advice on how to get started? Should I be looking to get a whole new wiring harness or just going one by one with new wiring connections?

Adding some pics for reference. Thanks in advance for the help.

Sorry the pictures are all upside down. I can t seem to modify, maybe a moderator can assist.

First thing would be to get manuals, Operator's manual and Service manual. The Service Manual will have a wiring diagram. I would suggest OEM manuals with an I&T manual as support info, if you want. The YT store has some or you can go to AGCO parts books which has a link to AGCO Publications where you can get OEM manuals. eBay sometimes has used OEM manuals.

http://www.agcopartsbooks.com/partsbooksn/login.aspx?region=northamerica This photo should help you get to the parts book for it. On the AGCOpubs home page there is a phone number in the upper right if you want to talk with someone, if you aren't sure of the right manuals for your tractor.




According to the parts book your oil pressure and coolant temperature gauges are mechanical. The ammeter and fuel gauges are electrical. You might want to consider replacing the ammeter with a voltmeter (or adding one) if you are rewiring it. Have you used a volt meter to check the voltage at the battery terminals when running to see if it is charging, or is your saying, "it doesn t seem to be at the moment", just a feeling? People will be looking for fact to be able to help you. If you don't have a hand held meter (VOM, Multi-meter, etc.) you should get one. It will provide better info than a test light when you have problems.

Since it is a diesel you only need a few wires. Also looks like a single wire alternator which simplifies things.I'd rip out the old wires
and rewire with only the minimum required. The volt meter mentioned is a good idea. I have replaced the amp meter with a volt meter on most
of my tractors.

(quoted from post at 20:04:07 01/19/20) Since it is a diesel you only need a few wires. Also looks like a single wire alternator which simplifies things.I'd rip out the old wires
and rewire with only the minimum required. The volt meter mentioned is a good idea. I have replaced the amp meter with a volt meter on most
of my tractors.

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Appreciate all the tips. I ve got a manual with the diagrams but mine is so different than the OEM wiring, it makes for a mess. For example I don t see an ignition switch or voltage regulator anywhere on the tractor, which seems like half the diagram.

As for the charging, I suppose it could be charging some and be weak, but when I compare my battery voltage with a handheld volt meter, it reads 12.7 before running and then 12.5 after its running (I m assuming because I just cranked the engine over)

I ve got lots of reading to do!

As for the Ignition switch you are looking for. It doesn't need an ignition switch as you have a mechanical, not electric, fuel shut off. I believe they originally used a key operated starter switch, part number 504809M91. It might have looked like an ignition switch, but it was just a momentary switch spring loaded to open (off), so a starter button could easily replace it. Removing the key from the original starter switch would have prevented a person from starting it, just as removing the key from a true ignition switch, as was used on the gas engine tractors would.

The fuel gauge was likely powered from an oil pressure switch mounted under the oil gauge from the parts book. The oil gauge was likely replaced and the person doing it didn't understand (or didn't care) about the fuel gauge and considered it unnecessary, so threw the oil pressure switch away with the old gauge. The oil pressure switch may have controlled other thins as well, the electrical drawing should show it. There is a possiblity the oil switch was relocated, you will have to see if you find one somewhere on the engine.

Your photo of the alternator appears to be a Delco one wire alternator, regulator is internal. It looks like the one wire goes right to the battery cable lug on the starter solenoid. If so that would bypass your ammeter and it won't show charging amps, even if it is working. Other photos you posted look like the wiring has been "worked on" before, so it is not surprising it doesn't look like the drawing. You will need to use the electrical schematic drawing to figure out where wire go for the items you need to hook up. While your photos don't show everything it looks like it may already have the minimum wires needed as Phil mentioned.

Between the parts catalog and the drawing in the manual you can compare what you have and build new. A new harness likely will not match completely to what you have and may take some rework. Unless you want to do a full restoration I agree with Phil and would suggest you build a harness for it.

From the BigDean cd.

That is a good drawing to use. If your alternator is a one wire Delco, as it appears to be in your picture, you do not have, or need, the red and blue wires shown going to the alternator in BigDean's drawing.

lots of parts information in the Agco parts book. https://na.apb.agcocorp.com/p/masseyferguson/651199/l/00-00
Untitled URL Link

(quoted from post at 21:31:58 01/19/20) From the BigDean cd.

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This is a very good picture for wiring. Could someone post a picture of the wiring for a gas 135? I need it bad.

You just need a wire from the I terminal on the key switch to the + terminal on the coil and a wire from the coil - to the distributor, to use that drawing on a gas 135.

You may want to go to my post above with the info on manuals and get the Operator's and Service manuals for your tractor, if you plan on keeping it.