I need some help putting my brake lights on a switch so I can choose to no have the lights show when i press the brake. I'd like the switch to either have the brake lights funtion normally or to have a small LED activate to tell me when the brake lights are off. I've had some really bad luck playing with electrical systems and i dont feel confident doing it all on my own, so if someone could give me a diagram,schematic, or How-to it would be greatly appreciated.

ETA: Its a 92 F150 XLT, short wheelbase, 5.0 EFI

 

I also want to make rear running lights optional, but on a separate switch.

 

You can find some excellent wiring diagrams in Haynes PN 36058. You need 2 SPDT switches - preferrably illuminated. Check boating supply stores. Wire them so the power FROM the brake/headlight switch goes to both outer terminals, and the center terminal goes TO the taillight circuit. With the switch one way, power will flow normally to the taillights. With it the other way, the switch illumination lamp will consume all the voltage, letting you know the taillights are off.


Why do you need to do this?

 

Running from the cops/fleeing the scene of a crime?!?!?!? I can only see that as a huge liability if anyone ever rear ends you or something of the sort.

That being said there is a hot wire (just check with a voltage tester) going to the brake switch providing power, you would just need to put a switch inline with that, perhaps use a lighted toggle switch for safety. Use your onw judgment whether or not this is a smart thing to do.

I really don't like the idea becuase My Fiance' and I were in a bad wreck in her Eclipse about 3 yrs ago due to some piece of Sh#t with inoperable tail lights, luckily (for us) there were more than one vehicles involved and multiple witnesses and it was found that it was ruled the cause of the accident was from the inoperable taillights. Damn near totalled car, trip to the hospital (thank god for airbags and seatbelts)legal bullcrap, etc. All results of someone who didn't check some of the most important safety equiment in their car.

This was on a 65mph highway and the car was at a dead stop, someone could have died, don't think I would want that on my conscience if I forgot to switch my tails back on or my wiring somehow failed.

JMHO

Josh

 

Also keep in mind that the brake light circuit feeds a number of other critical systems. The first one that comes to mind is the ABS... without that feed, the system won't know you're braking and could fail to engage. The second system that comes to mind is the cruise control: It may not cancel when you're trying to slow down. The third is the afore-mentioned inability for people behind you to know that you're braking.

It's such a bad idea on so many different levels that I would not recommend even attempting to defeat them. They're there for a reason, and, imho, to defeat them is a foolish, reckless, and irresponsible act at best.

-Joe

edit: That being said, I could see a potential practical application of it.... there are certain conditions when one might want to disable them when in use, say, maybe in war-time, to prevent the enemy from being able to see you from the air.... but I highly doubt thoat condition applies here.

 

I think I followed where Steve83 was saying to install the switch, and it also sounded like the shift interlock would be taken out as well, if I followed correctly, I might not have. Also, I am not 100% sure there is a shift interlock on that MY.

So, if you installed it wrong, and started the truck, it would not leave the Park position, without turning the truck off, move the key back to the first position, move it to neutral, start the truck, and then pull it down into drive.

I don't know what the application would be for this aside from trying to create a large court case for a settlement, or doing a runner from the LEO, in the states here.

 

'92 was the first year for the brake-shift interlock solenoid on the column. The switch would have to be in the NORMAL position for it, the RABS, or an E4OD transmission to work properly (BOO input). But there's a redundant safety switch on the cruise, so it would still disengage. It's the one that got recalled for starting fires.

 

The SCDS will only work to kill the poer to the cruise if it's not full of fluid to begin with. It can be full of fluid withot showing any outward signs of a leak, and that could cause the contacts to be bridged without necessarily grounding-out, even when the brakes are applied.

Of course, that's if and only if the 92 used the SCDS as an input to the servo to begin with... I can't be sure of that offhand...

-Joe

 

Well, now that I think about it...

'92 was also the LAST year for vacuum cruise servos, so even though it doesn't have a SCDS, it still has a redundant cancel mechanism on the brake pedal. It's a vacuum dump valve - dead center 9C727.



But even if the SCDS is full of fluid, it will still work. The plastic side can't hold the pressure that the MC generates, so the diaphragm would just push fluid up into the connector & through the wires (like they're known to do).