1968 MF 135 diesel wiring

[Whistlin10Speed]

I recently bought a 1968 MF 135 Perkins diesel that runs great, but the wiring is a disaster and the gauges do not work aside from the oil pressure gauge. Does any one have any recommendations on a wiring harness/ diagram that is easy to follow?

It has an alternator, I’m not sure if it was originally 12v or 6v and was converted. It has some wires that are just capped off and don’t go anywhere, some are broken, the headlights don’t work, and as I mentioned neither do the gauges.

I would like to completely rewire the tractor and get everything working again but I am not exactly sure how to go about it. I have rewired a tractor before but I can’t find much good info on this particular tractor’s wiring.

 

[Jim.ME]

The starting point is to get the manuals. MF put the wiring diagrams in many of the Operator's manual, that is where they are for the MF 135. You are in luck as there is a pdf copy at Manualslib.com that you can download and save, for free. Here is a link to it.

MF 135 Diesel Operator's Manual

The Delco Remy 10DN externally regulated 12-volt alternator was OEM at that time. You will need to confirm that is the one currently on your tractor. The complete wiring diagram for the tractor using that alternator/regulator is in the manual, if for some reason a later internally regulated 1 or 3 wire alternator is now on your tractor, minor changes to the wiring diagram will be needed in the alternator/regulator area, the rest of the wiring remains the same. One thing you will see in the wiring diagram and have to remember on a number of MF diesels is that there is no ignition switch. An oil pressure switch mounted to a tee behind the mechanical oil pressure gauge was used to excite the alternator and to turn on the fuel gauge.



You should be looking for (and purchase) a copy of the service manual (MF part # 1448813M1), if you plan to keep the tractor. It will have info in things like setting the valve of the engine you will want in the future.

Here is a link to the online parts book at AGCOparts.com.

MF 135 parts book.

 

[Whistlin10Speed]

Thank you. One thing that confuses me is it has a generator gauge on it, which makes me wonder if it was converted from 6v to 12v. I thought by 1968 they came factory as 12v.

Also, it has a newer style alternator with one wire to it, and one to ground on the block.

 

[Whistlin10Speed]

Also, I don’t see a wiring diagram in the operators manual.

 

[m16ty]

There are wiring diagrams in either the operator or maintenance manual.
If you have a 1 wire alternator though, the wiring is very minimal and pretty self explanatory.
What is a “generator gauge”? Do you mean it has a amp gauge instead of a volt gauge?

 

[Jim.ME]

Also, I don’t see a wiring diagram in the operators manual.

Page 44 of the manual has both the diesel and gas diagrams, page 45 has a headlight schematics diagram. Lighting did vary some so that might not be the same as your light locations, but it gives you the info needed to wire them.

Generator gauge? The 135 originally had an ammeter. Ammeters show current and the same ammeter can work on either a generator or an alternator.

A look at the parts book shows you alternators were used starting with 9A38905 and after. What is your serial number? If it is a lower number it would have had a 12-volt, negative ground generator per the service manual. If the voltage regulator got left on the tractor when the current alternator was installed looking at it will tell if it is for a 10DN alternator or a generator. The 10DN regulator terminals are plug in as the picture I posted for you. The generator regulator will be slightly bigger and have screw terminals for the wires.

You say it has a one wire alternator so the wiring in the charging system circuits will need to change a bit.

 

[Whistlin10Speed]

It is a 9A49480. It has a gauge that says “generator” I assume it is used as an ammeter gauge but it does not function so I don’t know. I will look back through the manuals and see what I can find. Just don’t want to take the old wiring off and have a hard time getting it wired back.

 

[Whistlin10Speed]

There are wiring diagrams in either the operator or maintenance manual.
If you have a 1 wire alternator though, the wiring is very minimal and pretty self explanatory.
What is a “generator gauge”? Do you mean it has an amp gauge instead of a volt gauge?

I’m not sure, it has a gauge that says “generator” I’m guessing It’s used as an ammeter but it doesn’t work so I don’t really know.

 

[Jim.ME]

It is a 9A49480. It has a gauge that says “generator” I assume it is used as an ammeter gauge but it does not function so I don’t know. I will look back through the manuals and see what I can find. Just don’t want to take the old wiring off and have a hard time getting it wired back.

By your serial number it should have come with the Delco Remy 10DN. Delco called them Delcotron generators when they were introduced, before the term alternator became common. A generator or the "Delcotron" would use an ammeter, you are worrying about what some company labeled the face of an ammeter. Does it show numerical ranges or just colored scales? If I was rewiring the tractor and the ammeter was no good, I would change the wiring for it and install a voltmeter. A voltmeter needs to be switched on and off so it would be powered from the oil pressure switch I mentioned and the second wire on it would go to ground. The wires on the ammeter would move to the battery terminal of the starter solenoid, where power to the ammeter should currently be coming from.

 

[Whistlin10Speed]

It does not have a numerical range, doesn’t really have colored scales either just a white needle.

Is there a kit anywhere that comes with the harness and new gauges?

 

[Jim.ME]

It does not have a numerical range, doesn’t really have colored scales either just a white needle.

Is there a kit anywhere that comes with the harness and new gauges?

This site has a parts store start by checking what they have, you can click on Tractor Parts in the banner above the forum to get to the store. They show a harness for the UK 135, but not yours. The harness and gauges may not come together as a kit. You may have to call them as not everything is shown. The other thing is you will need to study and ask about the harness as a harness made for the alternator will be made for the 10DN and its regulator. You may find a harness for a Delco 3-wire alternator, someone might make one for a one wire Delco type, research needed. Finding them requires studying descriptions and asking questions. The basic tractor wiring harness and the harness for lighting are often two separate harnesses. When you reduce the wiring to what the basic tractor needs, making it is not that hard, and you say you have done one before. Along with YT and PartsASAP, their parent company, Brillman Company is a quality electric component source.

 

[m16ty]

I’ve rewired lots of tractors, but never bought a wiring harness. There are so few wires needed, I just make some something up myself.

 

[Jim.ME]

I’ve rewired lots of tractors, but never bought a wiring harness. There are so few wires needed, I just make some something up myself.

Likewise, in the past few months I have done a couple MFs about like he 135 and a JD about the same size. A copy of the wiring diagram, note the colors (& gauge) I use and any changes from the OEM diagram. Make a clean copy when I finish and keep it in the manual with the original diagram, for future reference if needed.

A newer tractor with more electrical gear, I would consider buying a harness if it was a section and has specific connectors, but not a 1968 MF135.

 

[Whistlin10Speed]

Likewise, in the past few months I have done a couple MFs about like he 135 and a JD about the same size. A copy of the wiring diagram, note the colors (& gauge) I use and any changes from the OEM diagram. Make a clean copy when I finish and keep it in the manual with the original diagram, for future reference if needed.

A newer tractor with more electrical gear, I would consider buying a harness if it was a section and has specific connectors, but not a 1968 MF135.

That doesn’t sound like too bad of an idea, just copy the color and gauge of wire and then follow the diagram from there? I have only rewired a 1953 ford and it was a premade harness with everything you needed very simple.

What’s a good place to source the wire?

 

[m16ty]

That doesn’t sound like too bad of an idea, just copy the color and gauge of wire and then follow the diagram from there? I have only rewired a 1953 ford and it was a premade harness with everything you needed very simple.

What’s a good place to source the wire?

I usually just go with 14ga wire for all the loads under 15amps. You could use smaller wire for some of the smaller loads but just sticking with 14ga simplifies things and you don’t have to have different size connectors.

For a 1 wire alternator setup on a diesel. You usually only have 2 wires going to the engine, one to the alternator and one to the starter solenoid. Then you’ll usually have a couple wires going to the fuel sender and that’s it besides lights.

 

[Jim.ME]

I use 14, 12 and 10 gauge for the most part. To me 14 stands up better than 16 and 18 gauge called for in some diagrams. Also, a good selection of 14 in multiple colors is less expensive than multiple colors in 16 gauge as well as the 14.

For the most part I get wire and connectors (Standard and Grote brands) from the auto parts store I use. That is mainly because I have an account with them, and we do enough with them that they deliver orders right to our shop. It may be a bit more expensive than getting things from eBay, Amazon or some of the online stores, but not using up the better part of an hour to make a trip to the store to get things is worth a lot most days.

 

[m16ty]

I use 14, 12 and 10 gauge for the most part. To me 14 stands up better than 16 and 18 gauge called for in some diagrams. Also, a good selection of 14 in multiple colors is less expensive than multiple colors in 16 gauge as well as the 14.

For the most part I get wire and connectors (Standard and Grote brands) from the auto parts store I use. That is mainly because I have an account with them, and we do enough with them that they deliver orders right to our shop. It may be a bit more expensive than getting things from eBay, Amazon or some of the online stores, but not using up the better part of an hour to make a trip to the store to get things is worth a lot most days.

That’s what I was getting at, I don’t use anything smaller than 14.

 

[Whistlin10Speed]

Any other advice you guys have? I work in construction and am very mechanically inclined when it comes to engines and moving parts but electrical is my weakest thing for sure.

 

[Jim.ME]

That’s what I was getting at, I don’t use anything smaller than 14.

Good enough, I was typing and didn't see your post until after I hit send.

Do you have suggestions for a source(s) for wire for him.

 

[Whistlin10Speed]

would it be easier if I replaced one wire at a time so I don’t get confused?