Blackout light switch bypass with pictures

[MarcusOReallyus]

Someone was asking recently about bypassing the BO light switch, and I could not find a good how-to on it. Since I did it on my truck today, I decided to take some pics and write it up.

Tinstar and cucvrus, please avert your eyes. Non-standard mayhem is about to begin.

The first thing I did was to remove the dash panel, then drill out the three rivets holding the BO switch panel. Dunno why they needed to be riveted in place!

With the panel removed, I unplugged the two switches. No worries about getting the plugs mixed up - they are different. On my truck, the right switch is the master switch with three positions. Top to bottom they are: Service lights, ALL OFF, and Blackout.



The left switch is a momentary OFF switch for the BO lights. There is no need to do anything with this switch. Remove it or leave it in place, plugged in. It doesn't matter.

With the switch plate removed, I then used my meter to determine the function of the master switch. There are two columns of three contacts each, as seen here:




The left column is electrically isolated from the right column. They are never connected no matter the position of the switch.

In the diagram below, I used red lines to show where there is continuity for each of the three switch positions:



As you can see, when the master switch is in the middle position, nothing is connected. No lights will work. Nada.

When the switch is in the top position (Service Lights ON), the bottom rows are connected to the middle rows. Remember, there's no connection between columns, only between rows within a column.

When the switch is in the bottom position (Blackout Lights ON), the top row is connected to the middle row.


So, where does that leave us? Howzaboutdat? This is actually very simple! In order to have the service (civilian) lights working all the time, all we need to do is to connect the middle row with the lower row. Since the connectors on the backs of the switches are standard .250" tabs, we can just make up some short jumpers using some wire and some male .250 connectors. I decided to use some 10 gauge I had handy, to make sure that my jumpers would not be causing any voltage drop in my lighting circuits. 14 gauge is probably enough, though.


So, here's what the jumpers look like in place:




Lastly, I threw some electrical tape on it just to make sure that nothing will vibrate out of position.




Tuck everything up and tie wrap things in place so they don't dangle, put the switch plate back in place, and we're done. (Well, I did sneak in another mod. I put a momentary ON in place of the left switch for a manual GP backup. The hole is already there, and it's a standard size, so....

The end result is that your service lights (the regular civilian lights; headlights, tailights, turn signals, brakes, all that stuff) will operate normally as if there were no BO light system. Your BO lights will not turn on at all. Both the right and left switch are non-functional.


That's all there is to it. Two jumpers. Everything works fine, and if I ever repent of my sin in modifying The Sacred Design, I can just pull the jumpers out and put everything back like it was. No cutting, no splicing, no monkeying with the stock wiring.

I hope this is useful to someone!

 

[Matt5]

I got a truck with this done to it (be it not as nicely), wire was melted along with the plug, I just pulled all that stuff out, slapped the switches back in, never had a problem or had to worry about it again. I did not like wires shoved into plugs and melted.

Also seems like this should be in the mod forum.

 

[ehuppert]

I still use my B/O switch. Works out nicely for the plow lights! Not so hot when it gets knocked to the middle and you drive around with no brake lights!

 

[MarcusOReallyus]

I got a truck with this done to it (be it not as nicely), wire was melted along with the plug,

He probably used some wire that was too small for the current. That's why I went with 10 gauge -to make sure that would not be a problem.

The jumpers are just taking the place of the switch function. That's all. Nothing changes functionally about the circuit, except that it no longer has the possibility of getting knocked into the ALL OFF position. So, if the wire gauge is adequate, there's no place for it to be a problem.

 

[Recovry4x4]

Let me add this for future reference and newer members. If you own an M1010, there is a relay activated when the right switch is left in service drive. This means if you bypass the switch, you will have parasitic drain. I don't recall the function of the specific relay. If the switch is bypassed or left in service drive, you'll have to compensate for that drain.

 

[MarcusOReallyus]

Great point! Not being a 1010 guy, I didn't know that.

 

[dmetalmiki]

I would just take the bulbs out.

 

[MarcusOReallyus]

I would just take the bulbs out.

That doesn't solve the problem of bumping the switch into the "All OFF" position and losing your lights.

 

[Matt5]

Um, so in an electrical circuit... the smallest wire is the circuit size... pretty sure that aint 10 gauge on the plug so going that size, pointless to go that large...

Odds are the plug melted... not from wire size... from a poor connection... that is why the *plug* would melt lol...

Also never knocked it to off lol... idk how... my plow controller is right there as well... never hit that thing...

Either way, this seems like a mod that should be in the *mod* forum.

 

[cucvmule]

Have you ever heard of fusible link wire and how it works?

 

[MarcusOReallyus]

The circuit is already fused. The jumpers are doing exactly what the switch does in the "Service Lights" position. Does the switch have a fuse built in? Nope. So the jumpers don't need to be fused.

 

[cucvmule]

Yes most wiring is fused, not all. But as there is current and you are bypassing a switch that is controlling current with a larger wire you have in fact created another fusible link, of the existing wire. Per my response, using wire of same gage and replacing switch there is still some resistance even if you cut out and replace connector, or using larger wire.

I do not want anyone to chance melting more wire than the wire with the original problem, hence the fusible link. Melting more wire, in loom because of the original
wire melting will create a bigger repair. Hence other repair methods with relays, switches with melting, sticking issues.

 

[Matt5]

Um, if you have fuse... you do not use a fuseable link... lol... you *can't* make one unless you use a SMALLER wire... you can't turn existing wire with a fuse into fuseable link wire cause you put a larger gauge somewhere... like... makes no sense...

 

[cucvmule]

lmao don't panic what will melt threw first, large wire or small wire, like?

 

[MarcusOReallyus]

lmao don't panic what will melt threw first, large wire or small wire, like?

First, the jumpers are 10 gauge, the largest wires in the circuit. They are not going to melt. You can't get enough current through that circuit to even warm them up, let alone melt them. There is a fuse protecting them, and there are smaller wires that would melt first, even if there were no fuse.

Second, they are copper. Fusible links are not just smaller wires, they are a special alloy that melts at a much lower temperature than copper. They are designed specifically for the purpose of melting in order to open the circuit to prevent damage to the COPPER wiring.

So, I don't know if you were trying to say that these jumpers created fusible links, or if you were trying to say I should have used fusible links. Both are wrong. No fusible links are needed or wanted here.

 

[saltman]

I still use my B/O switch. Works out nicely for the plow lights! Not so hot when it gets knocked to the middle and you drive around with no brake lights!

Bringing this up from the past, was curious how you are powering the blackout switch/circuit when the master switch is in the service position? Did you jumper at the main service switch or is there an easy way to do it under the hood?

 

[ehuppert]

I "simply" rewired the B/O light circuit/switch to power the plow lights! So, either headlights are used, or plow lights. Don't remember specific wiring changes, did this mod ten plus years ago.... Pretty certain I will never need blackout drive or do nighttime convoys (again!)

 

[Wtcrab]

Thanks for taking the time to write this up. Its a great little hack, Don't know why people take every thing so serious, Wrong wire, wrong area and on and on. Thanks again.