Columbia Commuter - 5-wire Sachs wiring harness reman time!

Lorenzo (Sanguine Synergy) /

Onwards in the journey of the cursed columbia suchs!

So the brake lights on this one never worked on account of of the cable inside of the rear wheel well having been absolutely destroyed. Someone in the past apparently tried to fix it with MASSIVE rolls of electrical tape, which didn't work for obvious reasons

It was in a pretty annoying spot, and the rest of the wiring harness (especially the connectors/terminals) are in a really rough condition in general, so instead of dealing with the hassle of hodge podge repairs, I'm going to just remake the entire harness.

Oh and it begins

The joins of pixies.

I'll be making a "Manufacturing" schematic that includes all of the relevant information such as lengths of wire, terminals & types, alongside with other relevant information when it's done.

If anyone is interested, I can also make a few extra harnesses if anyone wants to buy one. But I'll only do that after I make sure that the new one fits in properly and without issue.

Re: Columbia Commuter - 5-wire Sachs wiring harness reman time!

Lorenzo (Sanguine Synergy) /

I don't understand how this brake light wiring is supposed to work.

Re: Columbia Commuter - 5-wire Sachs wiring harness reman time!

Lorenzo (Sanguine Synergy) /

And here's the preliminary layout so far.

Already started cutting the wire to length and stripping the ends, just need to wait for terminals to be delivered, and to find where I put my dang soldering iron for the switch ends

Re: Columbia Commuter - 5-wire Sachs wiring harness reman time!

Nice! this is a classy write up. Toss it in the wiki when you're done!

I think most of us just wind up halfassed running random wires and cutting and splicing as needed, but doing it up proper isnt much extra work and definitely much nicer. Even less extra work now that it's all laid out!


Re: Columbia Commuter - 5-wire Sachs wiring harness reman time!

Lorenzo (Sanguine Synergy) /

Yup, will do!

And now onto more progress, sorry if this is split over multiple posts, since it's easier to keep the specific things that I'll be saying sectioned

Re: Columbia Commuter - 5-wire Sachs wiring harness reman time!

Lorenzo (Sanguine Synergy) /

So I had a bit of a minor panic because I noticed that on the horn ground combination wire there was a tag inside of transparent shrink wrap. On one side it said 540, on the other 125.

I immediately went "oh damn does this thing have resistors in there" and promptly did some checks.

Ground to coil? Barely anything

Ground to bus bar? 3.4 ohms.

BUT! Remember that this wiring harness is junk. So I did a quick cut into wire itself, before the connectors, and shebam, resistance super low

I also decided to bypass the ground ring terminal itself since I didn't trust that either

Then I thought to myself that maybe there's a failed component in there, so I cut it apart

Just a paper tag inside of shrink. Why? I assume just to hurt my well-being 40-some years down the line. Thanks Columbia

Re: Columbia Commuter - 5-wire Sachs wiring harness reman time!

Lorenzo (Sanguine Synergy) /

Now, let's talk some "upgrades".

There's three parts of the wiring harness that are designed in a questionable way. The horn ground, and both of the brake light switch connectors that combine a green and white wire.

I find these "questionable" because they both attempt to combine multiple wires at the same time from a single connector. BOTH of the brake switch connectors either failed or had a wire snap off because of this design. And even then, this only "worked" originally because Columbia used super cheap wire with super thin insulators. I, on the other hand, did not use super cheap wire. I used automotive grade GXL wire, with hearty protective wire jackets. So combining wires into connectors like this isn't an option.

So the first "modification" I have on this wire harness remanufacture is to not do this awful design. Instead, any time two wires are being terminated into one connector, I instead will splice them together on the same side of an appropriately sized butt connector, and then run a short wire to the actual terminal at the end. All butt connectors will also have proper shrink wrap applied to them so that there's no stress on any of the wires that might result in the connection failing like they did on the brake switch wires.

Pictured below, the new horn bolt ground ring, and the two new switch connections (before being combined).


Now, on the subject of terminals. I will say that this entire project absolutely relies on using a proper ratchetting crimper- and ratchetting crimpers take a slight bit of getting used to before they can actually do any good. But once you get the hang of it, it's a breeze.

I also recommend getting an abundance of terminals (non-insulated). You will need them because sometimes terminals fail when you're putting them together. A ratchetting crimper will let you get the absolute best results from them, and you get the benefit of being able to get a huge bunch for super cheap. Like $10 for 50-100 from an electronics supplier.

To prove my point, here's a comparison of: Two failed test terminals because I used the wrong crimper die, a meh/failed terminal that didn't quite grab properly due to using one setting too high on the die, and a properly crimped terminal. This is all compared to one of the factory terminals, which is pretty damn bad.

Here's a better close up (and yes, I know, I needed a bit more wire stickout, I removed replaced this end after taking this comparison)


And finally, an issue of backwards compatibility. You ever noticed how all of the male spade terminals have a small hole in them? From the tiny ones on your brakes to the big ones from your headlights? Well, there's a reason for that- the female terminals are supposed to lock on to them- this is good, but also kind of bad.

A problem you may find when buying modern terminals is that they grip exceptionally well, and often have those locking tabs built into the female ends- even on cheap ones. Back in the days, you had to pay extra to get those, so vehicles were designed without them in mind. You may find that the 2.8mm spade terminals (yes, they are 2.8mm, not 1/8") are exceptionally difficult to remove from your brake switches if they have those locking tabs.

I found this out the hard way, took a solid few minutes of prodding with a toothpick before I could get a single one of those terminals off of the switch I was testing it on. 10/10 terminal, 0/10 for the locking. To account for this, you can simply press the locking tab press point out, then bend it once and it will snap. BUT YOU NEED ONE MORE STEP, you NEED to make sure to bend the locking tab itself up after snapping the press point, this is because the tab will snap just before the locking divot itself. So it's still there, but if you put it onto your switch, it will no longer have the thing for you to press to release it. That's no good

Re: Columbia Commuter - 5-wire Sachs wiring harness reman time!

Lorenzo (Sanguine Synergy) /

And everything is just about done! I just need to put the harness on the moped, adjust the length of the switch wires, adjust schematic accordingly, and replace the four dang fender bolts that snapped when I was taking the harness off (like seriously, why is M7 even a thing?? Dang DIN specs)- then everything should be fine.

Here's the current version of the wiring harness schematic & some reference pics

Whole harness

Bus bar terminal ends

Ignition coil and horn terminals

Brake/ running light terminals

Brake switch terminals

Headlight & horn switch ends, clearly need a size adjustment

And finally the small bits. From top to bottom, brake light ground, head light ground, and headlight power (hooks up to the end of the black cable coming from the switch to the headlight)

Will post an update after I get it all on the moped

Re: Columbia Commuter - 5-wire Sachs wiring harness reman time!

Lorenzo (Sanguine Synergy) /

Alrighty, the harness is on the Sachs. Because the way the columbia lays out the wiring harness is pretty stupid (it gets routed in between the engine and the frame- with no objective benefit) I have instead chosen to move the harness to the right side of the frame. This has resulted in a bit more tightness than expected, especially from the handlebar wires. THANKFULLY I expected something like this to happen, so I had already had an extra 2" of wire in the schematic for most of the handle bar wiring.

Since the last update, I have changed the schematic in the following ways to better fit the "new" mounting method, while not changing anything in a particularly substantial way to the stock harness:

+ 2" to the horn ground ring wire (the one that the two black wires are spliced into) for better install flexibility

+ 2.5" to the ignition coil ground wire for better install flexibility

+ 2" to both of the horn wires for better install flexibility

+ 2" to kill/ headlight/ horn wires, to allow for a service loop

+ 2" to both of the brake switch splice wires (the one that the white and green wire are combined into) to allow for the brake switch cover to actually move back. The shrink wrap from the splice currently gets in the way, which limits movement

- Changed both of the headlight bulb connectors from 1/4" fork to 1/4" rings. Makes no sense to get a different type of connector that isn't actually necessary, and I don't think anyone is hot swapping headlights enough to benefit from forks instead of rings.

I am currently considering whether or not to condense the wiring for the brake switches so that it doesn't use so much wire. Something like this

But really, this is penny pinching what, $1 in total? Meh

Aside from that, seems great so far

Will get update pics of how everything looks after the replacement petcock nut arrives and I deal with the broken seized bolt issue. Ugh

Re: Columbia Commuter - 5-wire Sachs wiring harness reman time!

your diagram makes me think of a uterus

Re: Columbia Commuter - 5-wire Sachs wiring harness reman time!

Lorenzo (Sanguine Synergy) /

This is the birth of a new era of 5 wire sachs diagrams

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