How to wire electronic switch?

I need to replace the driver in my Skilhunt H03. I got a fet + 7135 from Mtn Electronics, but I don’t know how to connect the switch. It is a 3 wire and I have only found info on wiring a 2 wire across the capacitor at OTC. I’m not sure which wire goes to which side or where the third one goes. On the switch the wires are labeled L, K, and K-. Thank you for any assistance, I look forward to having my headlamp working again!

The red wire is for the switch LED

OK! So I only care about the other 2. Thanks so much.

Just so I’m sure. I wire + to the left side of OTC and - to the right?

Edit: I found a clear picture and that is indeed correct. Mine wasn’t clearly marked enough to be sure.

Looking for a little more assistance. I got it wired up, but it’s not working right. I got the Emisar D4 firmware. When I push the power button it just blinks twice. If I push and hold it ramps, if I stop at the lowest it eventually blinks 8 times and shuts off. If I ramp up it will eventually blink 3 times and step down and it will keep doing that until it gets to the lowest and blinks 8 times to off. Did I do something wrong?

What you describe indicates clearly that the driver senses too low battery voltage
Narsil v1.2 needs the voltage divider for LVP even in 1S, while newer use the internal reference and supply voltage of the MCU

Both batteries I tried were at 4.16 volts.

That really means nothing.
What brand, model and how old?
On a direct drive Fet driver you need a battery that is capable of delivering the needed current.
If the battery is truly good to go, you may have contact issues of the driver to the housing, housing to tube… etc.
MtnE Fet+1 17mm drivers are made too thin IMO. Have had issues in many lights not getting contact properly.

They are good Samsung cells in very good health. Contact issues with the driver are a definite possibility. I love flashlights, but am new to modding, so this is really helpful. Also this is a 20mm driver not 17mm, does that make a difference? Should I have went with something else?

I’ve been reading some. Do I have the right driver for the H03 switch or should it be one for a momentary switch? Most of the info I can find is for the H03, but I see some mention of a momentary switch, I was pretty sure it was electronic.

MTN has different drivers
for a momentary light you need a momentary firmware

a clicky driver you could only operate with the tail cap

I’m pretty sure the Skilhunt H03 is an e-switch, so I got e-switch firmware. I made sure not to get click.

The D4 UI is for the momentary or E-SW. I am not familiar with the H03 so really can’t help with specifics. I did find this thread in a review with a pic of the SW. You should be good there.

Pics of what you are doing and anything else may help.

Looks like the H03 has a lighted E-SW. 3 wires? Unless you wire in a resistor you will not be able to use the LED on the SW. Also make sure you are using the 2 correct pads for the SW. Not the LED pad. DMM will indicate to you if the pads are correct as you push the SW.

While not specific to this light, I was able to get the L6 Lighted E-SW working with D4 firmware from info in this thread. Ignore the SMD resistors added to the driver but you get an idea where to mount the Esw wires to a driver. MtnE 20mm is not identical but very similar.
To get the LED functional on the esw, you will need to find a connection from the POS spring on the component side of the driver. Also put a 10K to 20K resistor in line to the LED pad on the Esw.

Great info! I really never utilized the led on the switch, so I actually removed the wire all together. I will do some more reading and update ASAP. You guys rock, I love good internet communities like this.

I really like your idea for the D4 UI on that light, I wanna see it work.

Thanks. I should be able to get it sorted early next week. Tomorrow and my weekend are shot so I won’t get to it then.

OK, it seems this is a lost cause with a 20MM driver. Do you guys know where I can get a good 21MM? I really like this light and want to get it working, but I feel I may need to find an alternative. The original driver just wasn’t durable enough and now I am having a hard time fitting a new one.

Lexel has drivers available. They even have Narsil.

Thank you for your help. I was a little ahead of you and managed to find my way there first. He actually had one already set up for an H03 still. I can’t wait.