Criss-Crossed Turn Signals

[ODRotorHead]

I have a new-to-me M151A2 with a quirky problem I've never heard of before. The previous owner installed an NOS Front Wiring Harness a few years ago. From the time it was installed, the front directional signals have worked backward. This gets confusing, so I'll apologize for "over-explaining."

Signal Control Lever Down (Left Turn) - the Right Front signal flashes.
Signal control lever Up (Right Turn) - the Left Front signal flashes.

The Rear signals operate correctly, so what I have is a criss-crossed system with the signals flashing on opposite corners.

Turn Signal System 001E.jpg

Background: The previous owner wasn't able to figure out why this was happening, so he came up with a field expedient solution. He went behind the instrument panel and cross wired the REAR signals (reversed the plugs) [22-460 to 22-461, and 22-461 to 22-460]. That got the signals operating on the same side, but the Signal Control was backward - Lever Down (Left Turn) - both RIGHT signals flashed. Lever Up (Right Turn) - both LEFT signals flashed. Worst case, I can probably live with that distraction, but I'll screw it up 90% of the time.

I'm hoping to get this sorted out once and for all.

My initial suspicion was that there was a problem in the Signal Control Unit. I took it off the vehicle and brought it in to the workbench. The information provided in the -20 is accurate, but I found the diagram confusing. I got out my magnifier and sorted out the socket pin assignments. If anyone else has had difficulty with this, this sketch may help [Please let me know if I made any mistakes and I'll correct the sketch.]:

Turn Signal Control Connector 003A.jpg

I opened the controller and cleaned it out, and then ran all of the -20 continuity checks. Everything checked OK.

Since the Directional Signal Control Connector is an integral part of the Front Wiring Harness, the wires run directly from the connector to the turn signals. The only connectors in those circuits (please correct me if I'm wrong) are the plugs/sockets on the back of the Composite Light Assemblies. 461 goes to the Left Front, 460 goes to the Right Front. Due to the design of the harness, there's no way to connect them backward.

So far I've determined that,
The Directional Signal Controller is working correctly, and
The Front and Rear Composite Light Assemblies are connected to their respective harnesses correctly.

At this point, my assumption (my guess) is that the Directional Signal Control Connector in the Front Wiring Harness was assembled incorrectly. I'm fairly certain the 460 and 461 inserts in the connector are reversed.

This is the connector with the "screw caps" removed:

DS Connector - FWD 001.jpg

DS Connector - AFT 001.jpg

Finally, here's my question . . .

Does anyone know how to disassemble this connector?

I tried pulling it out the back and pushing it through to the front, but it won't budge. I don't want to apply a lot of force and damage the assembly, so I'll hold off on any more "experimentation" and wait to hear if anyone has any advice or instructions.

I know I can just cut the 460/461 wires and reconnect them, but I don't want to take a shortcut that hacks up the harness. I'd rather take the time and make the effort to do it correctly.

Sorry this confusing post is so long. If you got this far, thanks very much for your patience. Thanks too for any information or suggestions you can offer.

Mark

P.S. For some reason, I'm restricted from viewing any images on the site, even in my own posts (Double Secret Probation?). Please let me know if any of the graphics in this post are messed up. I'll try to correct any errors. Thanks again.

[rickf]

Let me look through the wiring diagram, I seriously doubt that connector is wired wrong though. And you have to remember that the turn signals run through the brake light circuit. That will not cause this issue but the brake lights are integrated into the rear turn signals. The problem will be in the front harness, let me se if I can point you to an easy place to check.

[rickf]

Ok, The left and right rear turn signals go to C and E on the controller respectively and the fronts go to Right is A and left is B. So changing the rear was a bad idea and you need to change that back. You problem will lie between the A and B terminal of the controller and the front lights. What I would do is check continuity between one of the lights and the A or B terminal and see if the wires are plugged into the right terminal. The left light should be tagged at the light as 461 and should go to terminal B. Terminal A should have wire tagged 460 going to the right light. If this all checks out then unplug the wires from the lights and turn on a right or left turn signal and check for power at that wire out front. If the power is actually coming out of the controller on the wrong terminals then you have a turn signal switch. (controller)

Some of those switches can be taken apart and cleaned and serviced and some can't. If it has screws it can be taken apart. Watch for small parts and springs as you take it apart, go slowly. I have never seen one do what you are describing, usually one light will not work or an end won't work and that can be fixed by rapidly moving the signal arm back and forth several times to clean the contacts.

I have a couple of signal switches, where are you located? After paying 33.00 to send a small 5 pound box to California I am not sure I want to ship anything anymore!!!!!

[ODRotorHead]

Thanks for that comprehensive reply Rick. I'm embarrassed to admit that I forgot to do the continuity check you recommended. I'd planned to do it but got involved with a different project and forgot to get back to it. I'll complete that task tomorrow morning and let you know what I find.

The previous owner reversed the rear signal wires. I switched the rear signal wires back to the correct configuration before I started troubleshooting. The rear signals are working correctly, so I'm hoping there's no problem with the brake light switch and and the associated wiring.

I completely disassembled the signal controller a few days ago. I checked the wiring and the insulator, cleaned the contacts, and reassembled it. After reassembly, all of the -20 continuity checks were good. I'm all but certain the controller is functioning correctly. I neglected to mention that the previous owner tried installing a different controller unit and got the same criss-cross result. He ended up reinstalling the original controller and that's the one I'm working with now.

Thank you for kind offer to let me borrow your spare signal controller. Fortunately, that won't be necessary because I have two M35A2s and they use the same controller. I know I have a brand new (NOS) spare signal controller somewhere, but finding it might be a chore. It'll probably be quicker to just swap one out for a test if that becomes necessary.

I haven't found a detailed diagram of the signal system connector assembly. Can you give me a reference for that? Following the wires into the back of this connector, it appears that the wire connections are as follows:

A - 461 (Front Left turn signal)
B - 460 (Front Right turn signal)
C - 22-461 (Left Rear turn signal)
D - 22
E - 22-460 (Right Rear turn signal)
F - F
G - 467
H - H

Your diagram shows 460 going to A, and 461 going to B. Those two wires are reversed in my connector: 460 goes to B, and 461 goes to A.

I'll be able to verify that with the continuity checks tomorrow.

I know that #22 and #467 go to the master lighting switch, but I don't understand their functions. Can you tell me what the connections are for circuits 22, 467, F, and H? I'm guessing at least one of them goes to ground.

Thanks again for setting me back on the right track. I'll get the continuity test results to you ASAP.

Mark

[rickf]

I sent you a PM with the wiring diagram. If those two wires are reversed then you have found your problem.

[D Pizzoferrato]

Years ago when I built my tan AM151A2 from all NOS parts, I recall that the turn signal harness plug to the turn signal control switch (arm), made by Unicor (Federal Prison Industries) was wired as if 2 of the pins in the plug were viewed from the wrong side of the connector. I pulled out my wiring connector kit, grabbed the takedown tools, pushed out the pins and put them in their proper location. People forget that quite often, parts are surplussed because they don't meet specs.

[rickf]

My favorite saying! NOSR parts. New Old Stock Rejected Parts.

Thinking about that and what Dave said my original post about the plug not being the problem is probably wrong. Especially since you have already determined the wires are reversed. Unless you have the tools to pop the connectors of the wires out of their holes you are probably going to have to cut and splice the wires. The tools are small tubular tools that slide over the connector pin to release the tang that holds it in and then you can pull the connector out the back. Then you just slide it back in the correct hole and it clicks in.

[ODRotorHead]

I have finally identified the criss-crossed signal problem with (I think, I hope) 100% certainty.

After doing every conceivable continuity check, checking voltages in every possible lighting configuration, and meticulously documenting two pages of data, the "light" finally came on. I'm not sure if it was an "Ah Ha!" moment, or a "Duh!" moment, but I realized that the simplest and most certain way to determine the exact combination of pin-sockets to wires was to send battery voltage through the pin-sockets in question and see where it ended up.

M151 Turn Signal Diagram v002.jpg

First, I stuck a pin into socket A, and used a jumper wire to connect the pin directly to the battery. According to the -20 diagram, the current should have flowed through 460 to the Right Front turn signal. It did not. My able assistant (my wife) read 24 volts at 461; the LEFT Front signal. In the same manner, 24 volts into pin B produced 24 volts in the 460 connector at the RIGHT Front signal. Criss-Crossed.

Turn Signal Control Connector 004A.jpg

So that's it. The 460 and 461 wires are reversed in the connector to the Directional Control Unit.

I'm still hoping to disassemble the connector and reconfigure the wires if at all possible. I'd prefer not to cut the wires and splice them back together if I can avoid that. It's not a difficult task, but I don't want to start hacking up an almost-new harness if it might be possible to repair the connector instead.

Connector Repair 002.jpg

Thanks to all for your help and suggestions. If anyone has had any experience repairing one of these connectors, please let me know.

Thanks again.

Mark

[rickf]

Send a PM to Dave Pizzoferatto. He was the one that mentioned he had had that same problem and he rewired the socket. His info will be a few posts up.

[D Pizzoferrato]

I replied in a PM, but thought that the info may be helpful, so, here it is:

The removal tool is a tapered hand held punch used to push the pins out. Watch this video from about the 3 minute mark https://www.youtube.com/watch?v=lsRujT6 ... mb_rel_end

This kit is overkill; the military takedown tools are a simple non-mechanical tapered shoulder stepped drift. https://www.youtube.com/watch?v=8x726blInR8

Amazon has this one https://www.amazon.com/dp/B07QD4VKQP/re ... RydWU&th=1

[rickf]

See, I told you Dave would know. Dave knows everything, just ask him, he will tell you that.

Seriously though, Dave has been in this hobby a long, long time. He built a couple of vehicles from the ground up with all new parts. And he built a River patrol boat from an empty hull (two of them if I remember correctly) to a fully functional boat. THAT is dedication to the hobby.

And he has a wicked dry sense of humor.

[ODRotorHead]

Hi Dave.

Thanks very much for that information. I watched the whole video and learned a lot. Once you put me on the right track, I found a huge amount of information about connectors and how to maintain them. It's been an excellent education. Just knowing the proper terminology is a big help.

I checked my truck and the harness uses Prestolite M13486/1-3 16GA wire for connector sockets A through G (H appears to be 12GA but I haven't confirmed that yet.). The tools you referenced are top-notch, but a little pricey. Since I'm only doing two pins, do you think I could get by with one of these:

DCM Install-Removal Tool M81969_1-03.jpg

I watched this short DMC video tutorial on connector tools: https://www.youtube.com/watch?v=H1TIVh3VD4Q

They cover several different kinds of tools, but skipped over this type. Due to the fact that the sealing grommet is more than thirty-years old and is now probably a lot less flexible than when it was new, I'm a little leery of using the all-plastic tools (less than five bucks). The one pictured above has steel tips so I'd expect them to be far less likely to deform or break off inside the grommet. I can pick one of these up for less than ten dollars. It has to be "indexed," but I can work with that. Please let me know what you think.

If I understand correctly, different series' of tools (within the same gauge) are specified for different series' of connectors. I checked my connector plug and found a faint number stamped on the barrel: 11668586. The connector back shell is stamped: CM 11668590. I've spent a lot of time searching, but haven't been able to find a MIL-SPEC connector series associated with either of those numbers. Any thoughts on that?

The real reason I'm asking goes back to the earlier question about the compatibility of the tool, the wire, and the connector.

Thanks again for your help!

Mark

[D Pizzoferrato]

50 years to be exact. Probably before it was a hobby. I've also forgotten more than most people will ever know, but I have awesome research skills and the internet to keep me looking smart

[D Pizzoferrato]

Mark, I didn't see your prior response. I'm sure it wasn't there when I responded to Rick. Might have something to do with your post waiting to be approved. You need a stout tool to push the pins out of the aged rubber. The actual tools in the military wiring kit are way lowest bidder stuff compared to what I found online. I posted those so you got the idea of the process. The lowest bidder tools in the kit resemble a common drift punch. The difference being that the punch for removing the pins has a step in it. I had hoped you would have seen that in the videos I sent. The thin part of the drift extends into the body of the female connector, the wider part is the outer diameter of the connector. This configuration keeps the tool and pin connector aligned as it is pushed out. The force of the push is actually applied inside the connector. A similar tool can be quickly spun up on a lathe.

[ODRotorHead]

Thanks for all the information you've provided Dave. I'm still trying to figure out which connector type (series) I'm dealing with. Other than the stamped numbers I mentioned earlier, I don't have any idea which MIL SPEC connector type this is. I'm assuming your military kit was specifically designed for connectors purchased by the DoD. When I go online looking for tools, each tool is designed for a set or series of connectors within a wide range of connector types used in everything from spacecraft to submarines. I don't want to buy the wrong tool and end up damaging the contact locking mechanism.

Going through the DMC literature, I found a connector that "looks" like the one in question, but I have no idea if it's even close:

DMC Connector Series 3400 v001 .jpg

The link you provided for the first video didn't work for me ( https://www.youtube.com/watch?v=lsRujT6 ... mb_rel_end ). I don't remember how I found it, but this URL ( https://www.youtube.com/watch?v=lsRujT6dIZw ) took me to a Daniels Manufacturing video. The video shows a removal tool just prior to the 3 minute mark.

At 19:48, the section "Installing Contacts" begins and states "All contacts are installed from the rear." At the 28 minute mark, the video begins a section titled "Removal of Contacts." At the 29:26 minute mark it gets into the details of front removal contacts (no blue band) and the required tools.

I'm not sure how I got stuck on the idea, but I thought I was dealing with a connector that required both contact insertion and contact removal from the back side. If I finally have it straight (???), the connector in question is a front release/rear insertion type, and it requires two separate tools to accomplish those tasks. Thanks for straightening me out.

The Jonard Tools video was helpful. I found this old video helpful too: Overview of MIL-C-26500 Connector Design and Usage https://www.youtube.com/watch?v=QKuZz4NTHaI

That video provides some nice detail on the front release mechanism and how the tool functions to release and push out the contact.

I understand that wire size and contact size are not necessarily the same. But, . . . since the 460 and 461 wires are AWG 16, and the #16 contact size accepts AWG 16 through 20, is it reasonable to assume that contacts A Through G are #16? I found a reference that provided a #16 pin diameter of 0.062 in. (1.58mm). I'll try to measure the pins on the control unit tomorrow (when I finish shoveling snow).

Since the connector is an integral part of the wiring harness, there's no information about it in the -34P. If I can ever figure out the MIL number for this connector, everything else will fall into place.

Thanks again!

Mark