Light switch mod for safety

[Mogman]

These are the mods for bypassing the light switch so you will have full time brake lights and automatically switched horn and turn signals, I am combining the turn signals and horn to be switched because it is easier than the way I did it on my HMMWV.

This does involve cutting some wires, LEAVE ENOUGH LEAD going to the light switch plug just in case anyone wants to "undo" these mods but honestly I cannot see why anyone would want to put themselves, their loved ones and the public at risk!

AND of course "seal" the ends of any wires left loose, I use jelled heat shrink and pinch the end together while still hot (careful!)

 

[Mogman]

This is the mod for the brake lights, you can tap off 24V anywhere that is convenient and should use an in line fuse. (15A)
The most convenient place to pick up 24V is splicing into wire 15A at terminal F on the light switch, do not cut this wire away from the switch as it will still be powering the headlights etc.

It is pretty simple, cut away the three wires marked X connect the wire that was cut from terminal A (75A) to a fused 24V source and then connect the other two wires together and that is it, full time brake lights, IMHO this is the minimum that should be done to ALL HMMWVs, never be without brake lights again!
The two wires you connect together are 75B and 22A

 

[Mogman]

For the turn signals and horn cut the wire off of terminal J (467A) and connect it through a fused lead to a switched source, as RWH mentioned in another thread the heater feed wire behind the inst. panel would be a good one (27D) it is coming off of one of the run power circuit breakers behind the inst. panel

 

[G744]

Most of us leave it in the "Stop light" position all the time, so things work.

Forgetfulness is the first sign of something worse...

DG

 

[Mogman]

Most of us leave it in the "Stop light" position all the time, so things work.

Forgetfulness is the first sign of something worse...

DG

The problem with that is if you are (finished) driving at night and turn off the headlights it is just natural to switch it all the way off, also young fingers just love to twist levers, this mod guarantees you will always have brake lights, IMHO the risk is just too high to leave to chance.
But again everyone is free to chose which path to take.

 

[Maxjeep1]

The problem with that is if you are driving at night and turn off the headlights it is just natural to switch it all the way off, also young fingers just love to twist switches, this mod guarantees you will always have brake lights, IMHO the risk is just too high to leave to chance.
But again everyone is free to chose which path to take.

I like it! Having a little trouble with if I’m driving at night and turn off my headlights. Would I really be that concerned about not having turn signals and reverse lights?

 

[springer1981]

Why not make the change in the switch itself? No cutting harness wires and it looks like you could accomplish all of it internally. The brake light mod I like the idea of. The turn signal mod would allow the hazard lights to work with the switch in the off position. With both mods done it would be get in an go during the day light hours. The first "stop light" position on the switch would effectively be running lights and dash lights at that point and the "service drive" position would be headlight.

It would probably be best to disable the Black Out feature otherwise it would allow both to be used at the same time.

Any reason 2 jumpers as marked in red wouldn't do it? Updated it to include BlackOut disable cuts.

 

[Mogman]

Why not make the change in the switch itself? No cutting harness wires and it looks like you could accomplish all of it internally. The brake light mod I like the idea of. The turn signal mod would allow the hazard lights to work with the switch in the off position. With both mods done it would be get in an go during the day light hours. The first "stop light" position on the switch would effectively be running lights and dash lights at that point and the "service drive" position would be headlight.

Any reason 2 jumpers as marked in red wouldn't do it?

View attachment 874740

The only two issues I see are that lead F is the one hot all the time so the upper jumper does not seem to work, and also have you followed every one of the possible "backfeed" paths that you have created with the switch in every different position, that is the reason I isolated the switch from the modification, I am just too lazy to plot unintentional current flow in every conceivable switch position. Right off the bat I can see that possibly the dash lamps would be lit all the time unless you remember to turn them off, this could be a dead battery scenario.

EDIT, the actual concept of doing the mods in the switch are not a bad one, only you would need to cut some connections to not have unintended consequences but I do not have any extra switches to explore the feasibility of doing the mods in the switch, this also would not make the turn signal automatically work with the run switch, I am not a big fan of having to walk back and turn off the turn signal switch (or noticing after coming out of say a restaurant that the turn signal has been flashing) when the light switch is in service stop position which would be the effect if you wired the turn signal switch hot all the time in the light switch as there is no switched supply to the light switch.

On both my HMMWVs the lights are completely transparent just like on any of my civy vehicles only the turn signals do not automatically cancel.

 

[springer1981]

The only two issues I see are that lead F is the one hot all the time so the upper jumper does not seem to work, and also have you followed every one of the possible "backfeed" paths that you have created with the switch in every different position, that is the reason I isolated the switch from the modification, I am just too lazy to plot unintentional current flow in every conceivable switch position. Right off the bat I can see that possibly the dash lamps would be lit all the time unless you remember to turn them off, this could be a dead battery scenario.

I missed the F connection and was thinking the A was switched power to that side of the switch but now I see it is what feeds the dash light circuit. I corrected the picture. As for back feeding it should be relatively the same as what your suggesting. As long as the directionals and brakes aren't applied there shouldn't be any draw. If the horn circuit is branched off the stop light switch circuit then it would also be ok. I haven't looked at the entire wiring diagram yet but was just going off your pictures. I've not opened the switch assembly before either but I'm going to now. I like the idea. I would likely cut all the BlackOut wires so they couldn't be used. Then the only thing required to return to stock is a new switch.

I had not thought about it before just lived with the using the switch and nearly every time I forget to turn on the brake lights until I try to use my turn signal. LOL

 

[springer1981]

EDIT, the actual concept of doing the mods in the switch are not a bad one, only you would need to cut some connections to not have unintended consequences but I do not have any extra switches to explore the feasibility of doing the mods in the switch, this also would not make the turn signal automatically work with the run switch, I am not a big fan of having to walk back and turn off the turn signal switch (or noticing after coming out of say a restaurant that the turn signal has been flashing) when the light switch is in service stop position which would be the effect if you wired the turn signal switch hot all the time in the light switch as there is no switched supply to the light switch.

I was basically thinking out loud based on the pictures you posted. I see what you are saying about the turn signals however they are also the hazard light switch and any modern vehicle (last 50+ years) the hazard switch is always live. However the HMMWV I don't believe it is for obvious reasons. My turn signals don't have auto cancel either but I never miss the big green flashing indicator LOL. I am working on a modification to add turn sign canceling to my old style switch. Overall I don't think power to the turn signals is that much of a problem but that's just me. And I agree, you probably can't have the signals on a switched circuit without mods outside the switch itself.

I will look over an entire wiring diagram before diving in.

 

[springer1981]

Rev 2
The modifications in RED make the brake lights work full time. They also disable the Black Out lights so they can't all be on at the same time.
The modification in PURPLE does two things, first it moves the driving lights (tail lights, markers etc) to the STOP Light position of the switch. Second, it supplies power to the Signal Light circuit (directionals) and horn.

In this configuration, both Stop light and Signal light circuits are supplied with power from what appears to be an internal circuit breaker in the light switch eliminating the need for an external fuse.

The light switch operation would now be much more like what it found in a regular car or truck.
In the OFF position the Brake Lights, Directionals, Horn and Reverse lights will all function.
In the "Stop Light" position the marker lights, dash lights (note 1) and tail lights would come on.
In the "Service Drive" position the Headlights will come on if the Light switch is left in one of the ON positions
Note 1 The Dash lights need the dimmer switch to be left in one of the on positions.



Alternatively the Jumper between pin J and pin A could be eliminated and the junction circled in red be connected to a switched power source making the Directionals, Dash, Horn and Reverse lights only functional in the RUN position. That junction point could be attached to the Heater Power wire at the heater fan switch or CB-1. Or it could be attached to the Gauge Power at the dash or CB-2.

 

[Autonomy_Lost]

While this does seem like a good idea, there is some downside. I occasionally do night vision driving, and like to have full control over the lights. While not a great idea (or legal) to drive on the road at night with no lights, its certainly legal and fun to drive in the woods with no lights and night vision.

 

[G744]

Indeed. It is a military vehicle, complete with well thought out features for use as such.

If you want "safety features" go buy a 4WD SUV.

DG

 

[springer1981]

While this does seem like a good idea, there is some downside. I occasionally do night vision driving, and like to have full control over the lights. While not a great idea (or legal) to drive on the road at night with no lights, its certainly legal and fun to drive in the woods with no lights and night vision.

Yes, that is an easy one, don't do it. I never use BO and I regularly forget to turn on the stop light (no brake lights) until the first time I go to use the directional signal and it doesn't flash, then I remember to turn them on. I personally would prefer not to get rear ended more than I would prefer to have the BO option. This modification will not be for everyone.

 

[springer1981]

Indeed. It is a military vehicle, complete with well thought out features for use as such.

If you want "safety features" go buy a 4WD SUV.

DG

To point One, you are correct, it is a military vehicle BUT I'm not in a war or the military.
Point Two, Why when I can easily make it safer for my everyday needs? Does that bother you so much to tell us to "go buy a 4WD SUV"?

 

[Coug]

I use a keyed battery disconnect.
I leave the switch turned on to the stop light position all the time.
When battery is disconnect is turned to off it won't draw any power, so all this work to bypass or modify the light system seems a bit excessive to me.

 

[FlameRed]

Wanted this mod as part of making the M998 street legal, which included: adding reverse lights, license plate light, redoing all the lights that did not work, housings filled with mud, bad grounds, broken lenses, etc. Around here, they love to ticket for any reason.

Bought one of the overpriced "kits" from a vendor to do this change too. What a waste. Just a simple relay with the some wiring changes. Actually, the way overpriced kit did not work and so it was returned.

Got the correct wiring changes from forum members here which work perfectly!

 

[mgFray]

(posted to the wrong thread.. ignore me)

 

[G744]

This crap is a slippery slope.

Next thing you know, you'll see MV's in rainbow colors, turned into limos with swimming pools, and full on wi-fi controls from home.

Bah.

DG

 

[springer1981]

This crap is a slippery slope.

Next thing you know, you'll see MV's in rainbow colors, turned into limos with swimming pools, and full on wi-fi controls from home.

Bah.

DG

Don't like it, don't read it. It's really that simple. My steering wheel lock would probably send you over the edge. LOL