If you are patient, can follow instructions, read/understand a wiring diagram you can build a new harness from all new materials that resembles your original stock harness very closely. If you have the remnants of your old harness that would put you a couple weeks ahead in your harness building.
The Army made this a reasonably simple task due to their tremendous efforts to keep all tactical vehicle production built to the most common standard possible. Vehicles delivered to the army during the 50's will all have virtually identical electrical components hense they have wiring harness that are also virtually identical except for lengths of each run. Their 1948 established standard wiring number system is a gift we seldom appreciate enough.
A 1950's Dodge M37 or Reo M35 harness can be modified to match an M38 chassis very easily.
The biggest problem folks otherwise equipped to deal with a new harness project must deal with is a place to lay out and diagram the entire old harness. Those with restricted space availability will have to due their harness layout and reconstruction in segments. _________________ Wes K
45 MB, 51 M38, 54 M37, 66 M101A1, 60 CJ5, 76 DJ5D, 47Bantam T3-C & 5? M100
I do have the space. After a few more mechanical steps are finished I will give this a go.
I had a HS/college friend who became some kind of Naval engineer. One night on the dorm floor I saw him pouring over a huge scroll-like document that turned out to be a flow chart for the construction of a building. I think every last nail, wire and bucket of cement was referenced on that time line.
Another guy on the floor worked summers at some aircraft design company. He was not an engineer but they paid him to help figure out efficient paths to run wires and stuff through the tight spaces.
If I transfer the diagrams to cardboard on the barn floor and then lay out the harness components , cut & crimp etc ...... then have a real wiring guy look at the result ...... maybe no smoked jeep. _________________ Don Alvarez
Retired HS Teacher
Central Florida
M38 Project
The reason I mentioned space is the original harness cannot fit on a 4x8 without reversing some of it's runs back and forth IE light switch harness to tail lights and head lights. These compressed bends in the harness have an impact on accuracy of measurements. The proper way is to use the harness as the full size model not a blown up paper diagram. You use the paper wiring diagrams as a reference only.
You should at least prepare a display surface the same rectangular dimensions as your jeep, 5 x 9 Ft. Remember the layout lateral surface will also need room for the vertical runs of the harness.
I prefer to stake the entire old harness to my board with all it's wrappings. Photograph it and sometimes trace it. Then remove all the sleeves and tape. Then remove all plug pins. Refurbish or replace all plugs. Then copy one wire at a time installing replacement pins and such and insure it is the same exact length. Then insert it back into it's original position and move on to the next wire. _________________ Wes K
45 MB, 51 M38, 54 M37, 66 M101A1, 60 CJ5, 76 DJ5D, 47Bantam T3-C & 5? M100
Went to the barn today and brought home the wiring harness material I bought last year before realizing that slow is the better way to go. Not very expensive and the ad mentioned M38 possibilities. We shall see.
I will do a little reading, look at the pics. then jump over on the Tech. DB with some basic questions about what I have on hand and what I may need. For now I am double checking my selection of components for the next push/ engine (they say soon), starter, flywheel, bell housing, brake lines.....lots of stuff that comes in early and late flavors..... I have all three flywheels shown in the comparison pics and several carbs, none of which are the right one.
It’s all right there in the TM’s and albums.
_________________ Don Alvarez
Retired HS Teacher
Central Florida
M38 Project
I see you are quite determined to point out that you saw it done on a 4x8 piece of something. I thought I explained the benefit of using an adequate surface area to avoid folding up longer wiring lengths. I never said it could not be done on a 4x8 surface. _________________ Wes K
45 MB, 51 M38, 54 M37, 66 M101A1, 60 CJ5, 76 DJ5D, 47Bantam T3-C & 5? M100
While working on getting the engine back in, yet another wiring harness idea jumped into the empty space between my ears. Maybe line the tub (which is sitting in the corner) with cardboard cutouts that follow the wiring paths and build the harness ‘in situ’.
I also had another idea but could not find my SkyHook, church key and tent stretcher.😁 _________________ Don Alvarez
Retired HS Teacher
Central Florida
M38 Project
Don, That can work but first you must have all electrical components installed in their correct locations before you start an in situ harness fabrication. _________________ Wes K
45 MB, 51 M38, 54 M37, 66 M101A1, 60 CJ5, 76 DJ5D, 47Bantam T3-C & 5? M100
Brian, If you didn't post it then someone with access to your equipment did or you have been hacked. The post was clearly posted yesterday the 18th. _________________ Wes K
45 MB, 51 M38, 54 M37, 66 M101A1, 60 CJ5, 76 DJ5D, 47Bantam T3-C & 5? M100
It's all starting to look pretty good. I hope you have an engine stand to finish the engine buildup on. Also I suggest you put that adapter plate hanging on the front of your bell housing on the back of the engine soon. It needs to be there BEFORE you put the flywheel on the engine. I couldn't see the back of your engine. Are the flywheel bolts already hanging in the crankshaft flange where they belong at this stage? _________________ Wes K
45 MB, 51 M38, 54 M37, 66 M101A1, 60 CJ5, 76 DJ5D, 47Bantam T3-C & 5? M100
The flywheel bolts are on the crankshaft flange. I put the mount on the bellhousing just to stage the shot. I have a HF engine stand and floor lift that helps with the heavy stuff.
Getting the engine back in the jeep will be a motivating step. _________________ Don Alvarez
Retired HS Teacher
Central Florida
M38 Project
M38 Wiring Harness Build
Here are most of the wiring parts I have on hand at this time including:
* NOS chassis wiring harness for the M-54 series 5-Ton 6x6 wrecker truck
* Greek Army tail light/trailer socket harness for the 2 plug type light switch.
* military headlight switch connection with about 15 inches of lead.
_________________ Don Alvarez
Retired HS Teacher
Central Florida
M38 Project
Last edited by Naugha on Sat Mar 26, 2022 3:24 pm; edited 1 time in total
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