M37 Barn Find

[jeffhuey1n]

Thanks to hendersonj, I can start hanging wire. “From humble beginnings”

 

[jeffhuey1n]

Picked up a starter relay and a new ballast resistor. Even though I super glued the old one, I’m not sure trying to use it was a good idea. Installed the the new resistor with no problem. Went to install the starter relay and more difficulties. The battery cable was routed over the transmission and tucked up against the frame. Got it disconnected from the starter but I couldn’t get the cable loose enough to properly route it. Underneath, in extremely tight quarters, I traced the cable to the transmission but for whatever reason, the cable has a giant ball of electrical tape on a 90 degree bend in the cable. No idea yet what’s all about. In order to find out I have to pull the transmission cover, which is being a pain. More tomorrow. As long as the arctic air mass stays away..,

 

[jeffhuey1n]

Got the transmission cover removed. Removed the passenger side floor panel. This gives me a bunch more room to work. Not sure why but the previous owner’s battery/starter wiring was very confusing. So, I removed about a pound of electrical tape, which was wrapped around the cable. There was a bolt holding two lengths of cable connecting the battery to the starter. Removed bolt and set aside one of the cables. Stuck a exacto blade in my finger, bled all over the trans. Now that I’ve christened the project, hopefully it’ll be less difficult. Anyway, hooked the battery cable to the newly installed starter relay. Ran a wire from the starter solenoid to the starter relay. Had to move the voltage regulator up near the alternator to make more room for the new starter relay. Cleaned up all the excess wiring and trash to get ready for continuing it’s harness install. Pictures below. One note: I’m using the below diagram to properly hook up the entire circuit. It can’t be all that bad if I follow the book?

 

[jeffhuey1n]

Today I was getting the little details that I missed earlier. The brake switch needed rewiring. The two connectors were just plain nasty. I think their wires were originally used on the Titanic! New wires and connectors installed. I’ll tag them into the harness next. I think I figured out the power supply for the entire wiring harnesses and how to integrate the M-37 harness, the 1961 Dodge D200 wiring harness and the starting circuit into one cohesive harness. The power to the M-37 harness appears to be coming from the BATT terminal on the alternator. The battery plugs into the starting circuit. The rear harness is installed exactly like the M-37 diagram. The front harness gets attached to the rear on the inner fender, pax side of the cab. For the most part, everything is routed through lightening holes in the firewall. Once that’s done, I can hook up the circuit breakers, light switch, etc. bit by bit, one step at a time. No pictures tonight. I’ll try to get some pics next time I work on it.

 

[jeffhuey1n]

Got the wiring harness routed to the high beam floor switch. Got the brake light switch wired. Keep finding little things that need fixing. Frayed wires, incorrect connectors (my fault) and a total lack of info on how to integrate the wiring for the engine with the stock wiring.

 

[jeffhuey1n]

Drivers side headlamp, blackout parking marker and blackout headlamp are all wired. I’ll have to dig through my humongous stash of little bitty screws to replace several that are badly corroded. Started getting the dash panel set up. Everything is in place for next time.
Not much more left of connecting. When all that’s done I’ll install covers over sharp spots. Can’t forget to reinstall the starter!

 

[jeffhuey1n]

Got most everything laid out and just need to do final connections. It’s been interesting getting it set up. The original connectors were the metal type. Interspersed are several of the rubber connectors and when all else failed, used the connectors you can get from Harbor Freight. Almost concerned that when I plug in the battery. Not sure if I’ll end up with a Back to the Future flux capacitor or a pile of melted wiring. Oh well, hope for the best and always have a backup in case Murphy pays a visit.

 

[M-37Bruce]

Crossed fingers too!

 

[jeffhuey1n]

Got the instrument cluster installed after making all the necessary connections. Had to replace the temp sending unit to temp gauge. The wire was too short and was in poor condition. I think I’ve got everything connected except the passenger side head light/black out marker and the #10 wire. This wire is the main feed that energizes the lights and several other circuits. Do I hook it to the voltage regulator, the “Batt” connection on the alternator or to the starter relay? I’ll have to think it through a while cause I want to get it right the first time. So far, this is my last technical issue. A couple pics:

 

[jeffhuey1n]

Finished up the passenger side headlight and parking/blackout light. List is getting shorter. Reinstall the starter. Connect the air horn, turn signal system (got to rebuild the whole thing from the turn signal, flasher unit to all the lights). And finally, wires 10 and 12. Both are the primary means of power for the lights and for all the gauges and ancillaries. Once I give a good look over, check for any stray wires, I’ll hook up the hot wires. Should be interesting.

 

[jeffhuey1n]

Got all electrical connections completed except for finishing the starter installation and then plug in the battery. If all goes well, I hope t have it running by Tuesday. Keeping fingers crossed it all works!

 

[jeffhuey1n]

Starter is installed but still needs the starter solenoid connection hooked up. Started clearing all the tools, parts, supplies and trash from the work area. When I try to start it, the less stuff in the way, the better off it will all be. Also cut my hand on the cut off end of a zip tie. That hurt! So I took my exacto knife (the one that flipped up in the air and stabbed my finger!) and trimmed all the cut offs (with”side cutters”). Never realized how much easier it is to use a knife to cut them with. A note of warning though: when using the exacto knife, extreme care must be taken ‘cause you can cut wires without meaning too! I also figured out how many tools I had in my tool box, ‘cause I had to put them all back into the box after having used them on the truck! Hopefully more later on. Edit: almost forgot, I have to still reinstall the turn signal system.

 

[jeffhuey1n]

Haven’t done anything yet. Bad weather mixed with a disorganized barn makes for a slow day. Still finding tools in really strange areas. Continuing the clean up. Hope to get something done today. Got to get my new truck inside the barn!

 

[jeffhuey1n]

Getting closer to finishing the truck. I need my son to help me with one last nut, the one that attaches the cable to the solenoid. Just can’t maneuver my hands in that tight of area. Been finding tools in the cab, in the bed, the engine compartment, the brake/clutch master cylinders and underneath the truck. I’m an expert at disorganization!

 

[jeffhuey1n]

Got the battery cable attached to the starter solenoid. Going over everything one more time. Just figured out that the two barreled carburetor is a Motorcraft 3DM2, originally installed on 73-77 AMC Jeep’s. Gonna be interesting getting everything reattached correctly... Hooked up battery. Nothing happened. Now for some troubleshooting ...

 

[jeffhuey1n]

Weather is a pain in the drain. Blizzard is hitting this area pretty hard. So far it’s dropped about. Foot or so. Kinda hard to tell with the wind blowing at 30+ mph. So, no outside to day. I’ll use the time to see where I mixed things up. I suspect it could be either wire #10 or #12. #10 comes out of the voltage regulator and 12 is supposed to attach to the distributor. Anybody else got a V-8 crammed into a M37? Dilute could use some assist.

 

[M-37Bruce]

Be safe, weather is all over the place, but no white stuff here.

 

[jeffhuey1n]

Be safe, weather is all over the place, but no white stuff here.

Haven’t been able to get out to the shop. Drifts a bit too tall for even me.

 

[jeffhuey1n]

Finally able to get to the barn. I downloaded several training schematics of wiring harnesses and components. After much head scratching, I think I’ve got part of the issue figured. There has to be a 12 volt power source in order to power up the truck. Wire #10 was one of two wires that were baffling me. So I did even more head scratching (good thing I’m almost bald!). I had installed the #10 wire to the alternator “Batt” connection. I removed it and redirected it to the heavy gauge starter wire, which was routed between the starter relay and the starter solenoid. As it was a commercial cable, there was a secondary wire connected to the terminal. I just plugged the #10 wire in and crossed my fingers and hooked up the battery. No earth shattering kaboom! In fact it was almost anticlimactic in its lack of sparks.
Anyway, with the wire reattached to the battery wire, I got the horn working. When I turned the ignition switch on, I tested the start button. It worked! So, #10 wire is solved. #12 is still not deciphered. According to the M37B1 wiring diagram, the #12 wire is supposed to got to the distributor. The only wire connected to the my distributor goes to the ballast resistor in one end and to the ignition switch on the other end. My thought is the 12 wire is unnecessary. If so, I can use the wire to power other lights, such as spot light, dash lights or maybe even an AM/FM stereo with a CD player!

 

[John Mc]

#12 is still not deciphered. According to the M37B1 wiring diagram, the #12 wire is supposed to got to the distributor. The only wire connected to the my distributor goes to the ballast resistor in one end and to the ignition switch on the other end. My thought is the 12 wire is unnecessary. If so, I can use the wire to power other lights, such as spot light, dash lights or maybe even an AM/FM stereo with a CD player!

Th technical manual TM 9-8030 shows that wire 12 goes from the ignition switch to the center post on the distributor (see pg 180 - at least on my copy). My truck had been converted to a hybrid 12/24 v system. The ignition was 12v and did not have the military distributor. The ignition coil was mounted externaly from the distributor. If I recall correctly, the #12 wire was connected to one of the terminals on the ignition coil, which I think then also connected to the distributor. (the engine is pulled from the truck and accessories removed at a friend's shop now, so I can't check.)