Miscellaneous Diagrams and Illustrations

[ODRotorHead]

I drove the M151 while serving in the Army, but only rarely. Being at best, a shade-tree-mechanic, and lacking any practical experience with the MUTT, I found it difficult to sort out some of the problems I've run into. I've tried to keep a record of my work so my son can eventually take over and enjoy the MUTT for years to come (I hope). Rather than taking a lot of notes, I generally find it easier to make sketches and diagrams - mostly adaptations of TM illustrations.

I'm particular about anything related to safety, so I started by trying to figure how the batteries should be configured. The illustrations I found in the -20 and -20P were a little confusing, but I eventually found what I needed:

M151 Battery Diagram 003C.jpg

. . . and a sketch:

M151 Battery Box Configuration 00A.jpg

The ground fitting in the illustration (#9) is missing, so I had to make due with a nut/bolt and two star washers.

I found some early illustrations that showed the positive terminal cable taking a tight bend around the front of the outside battery and another 90+ tight bend through the front wall of the battery box. When I took ownership of the MUTT, that cable passed straight through the battery box wall and made more gentle turns around the back side of the outboard battery. That configuration seemed to put less strain on the cable and is less likely to cause chafing, so I left it that way. Someone else may be able to evaluate the rightness, or wrongness of those assumptions.

After reading about the claimed benefits of the Battery Upgrade Kit, I decided to go ahead with the installation. Fortunately, the instructions that came with the kit were pretty straight forward with only one minor error related to the terminal covers:

M151 Battery Upgrade Instructions 004.jpg

. . . and a sketch:

M151 Battery Box Configuration 00B.jpg

My electrical configuration is about as simple as it gets, but for reasons related to safety I'm glad I installed the kit. If you have a lot of equipment installed, you'll find even more benefit.

[ODRotorHead]

My next problem was crisscrossed turn signals. When I signaled for a Left turn, the Right front signal flashed along with the Left rear signal. Opposite for a Right turn - Left front flashing along with the Right rear.

The previous owner informed me of the problem before I made the purchase. He had a partial solution, but I wanted it to work correctly. Knowing nothing at all about the M151 electrical system, I found this an especially challenging problem.

First I had to familiarize myself with the general layout of the wiring:

M151A2 Wiring Harness 003A.jpg

While inspecting the vehicle, I found the trailer connector to be a mud-covered mess of missing insulation and corroded wires. After cleaning it up, I found that someone had tried to correct that problem by covering everything over with gobs of silicone sealer. I wondered if something in that mess might be causing the turn signal problem, so back to the books. I found the topic a little confusing, so I decided to put all the information on one sheet in the hope of making troubleshooting a little easier:

M151 Trailer Connector Harness 005.jpg

I was able to find an NOS connector and the install was simple enough. The connector had to be replaced no matter what but, unfortunately, the new connector did not correct the turn signal problem. Back to the books.

First, I had to get more familiar with the lighting circuits:

M151 Lighting System Diagram -20 v010.jpg

Then narrow it down to the turn signal (directional signal) system:

M151 Turn Signal Diagram v003.jpg

[ODRotorHead]

Since it was the most accessible part to the system, I decided to troubleshoot the controller first. The controller is old and beat up so I took it apart and cleaned all of the contacts first. After reassembling it I ran through the circuit tests:

Directional Signal Controller Test 003.jpg

The controller passed every test, so that wasn't causing the problem either.

Next up was the cannon plug (slang for circular connector). The controller and the rear signals were working correctly, so the problem had to be somewhere in the front harness.

I had to learn what I could about the signal controller plug configuration so I made a couple of sketches:

Turn Signal Control Connector 003.jpg

Turn Signal Control Connector 006A.jpg

Through a lot of testing, I finally figured out that two wires in the connector assembly were reversed. I'm guessing, as others have mentioned, that the front harness (installed by the previous owner) had been surplussed out because it was defective. No reflection on the previous owner. No one could have known.

The next task was to figure out what kind of connector I was dealing with so I could find the right tools for the job. There were no markings at all on the installed connector, but I was able to find another signal control connector that was clearly marked. The results of my research:

MIL-C-5015 Connector Information 004.jpg

After reversing the wires in the connector and putting everything back together, I finally had a working signal system.

[ODRotorHead]

I won't bore you with more of the continuing saga of repairs and upgrades. I'll just post a few more illustrations/diagrams that might be helpful;

Lighting -

Composite Light Combo 001.jpg

Composite Lights Open Combo 001A.jpg

M-Series Signal Controllers - Combo 003.jpg

Light Switch MS51113-1 - with Text 0010B.jpg

[ODRotorHead]

Electrical system -

Originally part of the M151A2 Electrical Diagram:

M151A2 100 Amp Gen Diagram 005C.jpg

100 Amp Circuits:

-20 100 Amp Gen Elec Dia 001D.jpg

-20 SEP 71 - 100 AMP GEN 002B.jpg

[ODRotorHead]

Instruments -

M151 Transmitter and Gauge System Diagram 003.jpg

M151 Instrument Panel 004.jpg

M151 Voltmeter 006.jpg

[ODRotorHead]

M151A2 Pre Emissions Fuel System -

M151 Pre Emission Fuel System Diagram 001GB.jpg

Fuel System Diagram - Pre-Emission 010F.jpg

[ODRotorHead]

Just for fun -

M151 Electrical System Illustration 001.jpg

M151A2 Electrical System Wiring and Components 001A.jpg

And the wire numbers:

Wire Number Circuit Description for M151.docx

If you see any errors, please let me know.

[Horst]

Mark,

Will you eventually combine all your work into single pdfs (like one for everything electrical)?

I can imagine this would be extremely welcome by all of us.

[ODRotorHead]

I'll be more than happy to provide that for you Horst. However, . . . I tried doing that with some of the earlier files and found that after embedding detailed images in a Word document (.docx) and then converting it to .pdf, the image quality dropped off dramatically. The electrical diagrams were unreadable. I tried changing the settings in Word (Do not compress images in file. and Set default target output to - 220 ppi (the max).) but it didn't make any discernible difference.

I've read that converting with Adobe Acrobat produces a better result, but I don't have Acrobat and that's a fairly expensive option for an uncertain outcome.

I also tried converting the electrical diagrams from.tcw directly to .pdf in the hope of keeping files sizes down. For reasons I don't understand, entire sections of the converted files were blacked out. I haven't been able to figure out what's causing that. Image quality drops off a lot even just going from .tcw to .jpg, but at least the diagrams are still reasonably clear. I can push the conversion resolution higher and get sharper detail but the .jpg file size goes through the roof.

I'll keep looking for solutions.

To be honest though (sorry - bad habit of thinking while I'm typing), since all of the images I've posted are in .jpg (varying resolutions) anyone can pull them off and assemble them in a .pdf. Maybe someone in the group who already has the required resources (and the knowledge I lack) can help with that.

Mark

[Horst]

I know exactly the resolution problem you describe, except I do have the problem in Powerpoint. Same here, no matter what I change in settings, more than once the resolution is dramatically reduced.

At home I use a Mac and Apple's pdf program allows combining pdf without any other external help. On the Windows PC I am using a free program called PDF24 which can combine (with various other functions) pdfs for free. I believe there is also an English version of it.

In any case, if most of your work are pictures, then combining them into a Word file should be less of an issue.

You can send me the data you think make sense to combine them in a single file. Either email them to me or provide a cloud link (Dropbox, Google Drive, whatever).

[rickf]

I have an older Mac desktop that I got from the college I worked at to do photo work. Never got round to doing it but I just fired up that computer and as Horst says it does have Adobe on it. Many different types of Adobe at that. Probably because this computer was used in the graphics department at the school. I am not real familiar with the program but if you want to send me some files I will see what I can do. Horst has computer background so he can also help you I am sure. IF he ever has time at home to do it!

[FoxMike]

Thanks for these! Always appreciate your very detailed work.