Surefire M910 Question

I have a Surefire M910 that was sitting idle for a while, and just got moved to a new carbine. I put it on and...no workie.

Hrm.

I checked the obvious first. The batteries seem good, I replaced them with a known-good set, and still no dice. The next thing could be the bulb, but the LED navigation lights don't work, either. I find it unlikely that all three lights (two red LEDs and a high-output lamp) would go dead at once. So, something else is at work.

The light has apparently has a system-disable and a constant-on switch, in addition to two pressure switches for the white light and one for the LEDs. I THINK that I have tried everything in every possible order, and nothing seems to work. I looked on Surefire's website for a manual, but I could not find it (I, of course, pitched mine two years ago when I bought the light, I'm good like that).

Does anyone know what I might be doing wrong?

To clarify, here are the switches that I can ID:

Lever/Dial type deal, on the rear of the main lamp housing (tried it left and right, and all points in between).

Twist switch on the cap of the vertical grip (tried in every possible position).

Pressure switches on both sides of the grip.

Pressure switch for the LEDs, on the top rear of grip.

I swear I've tried every combination of the above. And yes, the light worked fine before. Also, I inspected the inside of the battery tube...no corrosion or other evidence of a CR123 mishap. The light was stored with no batteries on board.

Is there a switch I'm missing? Does anyone have a pdf of the manual, or a link?

Thanks,

Mike

PS For people who saw my previous weaponlight question, this is a different light on a different weapon.

Mike,

The rear level/dial is for Constant ON or Normal Momentary operation.

The bottom twist is for total Lockout.

It seems that you have tried about everything, but just to be picky...

- Are the batteries good?
- Did you insert the batteries with positive side UP (towards main body of light)
- Did you fully twist close the tailcap? The lock lever can make it seem like you are done when there is further to go.
- Can you unscrew the bezel, remove the bulb, and see if current is even going to the contacts?
- Is any of the obvious wiring you can see when you take off the picatinney mounting plate cut or broken?

Other than that, back to SF Customer Service!

Good Luck,

Dennis.

Dennis said:

Mike,

The rear level/dial is for Constant ON or Normal Momentary operation.

The bottom twist is for total Lockout.

It seems that you have tried about everything, but just to be picky...

- Are the batteries good?

Click to expand...

Yes. I tried several sets, that all work in other lights.

- Did you insert the batteries with positive side UP (towards main body of light)

Click to expand...

That's how I did it at first. I tried it the other way, too.

- Did you fully twist close the tailcap? The lock lever can make it seem like you are done when there is further to go.

Click to expand...

I hope so. Going further would require two grown man and a boy. I'll check again, sticking with finesse and not torque.

- Can you unscrew the bezel, remove the bulb, and see if current is even going to the contacts?

Click to expand...

Yeah, I'll be checking that next.

- Is any of the obvious wiring you can see when you take off the picatinney mounting plate cut or broken?

Click to expand...

No. It all looks solid.

Other than that, back to SF Customer Service!

Click to expand...

That's what I was afraid of. It's GOTTA be something with the lockout tailcap. I'm going to fiddle with that a bit (in a non-warranty-voiding way) before I ship it out.


Thanks,

Mike

Ah ha!

It was the kill switch. I think there is something wrong with it, but I got it to work. You have to turn it ungodly hard to go to "run", and if you turn it a 1/4 turn in any direction from there, it reverts to "off". This is seemingly the opposite of what you want on a fighting rifle. :sigh:

I'm not sure if this was something I did, something wrong with it from the factory, or something that failed somehow. One way or the other, I gotta call Surefire.

Thanks for the help!

Mike

Mike,

That's how my kill switch works. It's meant to keep the light off during storage and transportation, hence the hard to turn part.

In any normal use you would just keep it ON.

Glad you got it to work!

Dennis.

Yeah, but it's only hard to turn ON. It's easy to turn off. That seems very much backwards. You can finger-twist the cap so that the light is disabled with very little pressure, and then you need a pair of pliers to turn it back on. If that's by design, it's retarded (and I'm pretty sure Surefire thinks things through better than that). I'd hate to prone out and ground/twist/bump the tailcap and disable the light and then need my multi-tool to re-enable it. That's gotta be wrong.

Mike

Mike
Perhaps you could give SureFire a call and ask to speak to somebody with experience of the M900 Series WeaponLights. They may be able to confirm whether what you're describing is 'normal' or not. One outcome could be to try a replacement TailCap...