A single NFET will do it, hold on, and I'll draw you a circut....

 

Find the wire that gives the small reading at the hinge when the door is open, tap it, run a relay between that wire and the "puddle lights"

Easiest and most effective way.

 

Yeah thats what I was thinking before.... I just want it to be a very clean install. Even if there is .7V on there when the door is shut that wont be enough to make the relay jump.

 

Nope. That's how my rock lights are wired up. One wire is tapped at the hinge that tirggers the door ajar circuit that is ran to a relay that is then ran down to my lights.

I haven't had any problem since, and it's been well over a year. I just keep blwing the 55w h3 bulbs. FML... The get hot and are rapidly cooled by the rain water of OR. lol

 

Here ya go....this will do it:







The NFET gate won't pull any current( no DC, just charge / discharge current), like the coil in a relay will........

 

He is measuring that "small voltage" with respect to 12V, so the voltage is going to Vref, which is about 11V, when the door is open, and the switch opens.

 

The .7-.9 volts you measured is caused by the difference between battery voltage and the voltage available on the YE/BK wire going through the wiring and IC circuitry (SJB) causing a slight volt drop.

Hooking the LED's and or a relay directly to the YE/BK wire may cause your Door Ajar light to stay on or other problems. I think Takeda's solution using a transistor to isolate the circuit to directly control or to control a relay would be a better option.

 

Hmm, I've never used transistors in any of my jobs before, mostly I've done direct replacements. This might take some doing - Honestly I don't fully understand the schematic even. My electrical engineering was limited to EE101 =(

 

A relay isn't needed with a NFET.

 

wow didnt realize even with a relay that something like this was such a process lol wow
get some pics up, would love to see the result.

 

So the transistor needs to be connected to

1 - ground
2 - LEDs (positive?)
3 - switch wire (yellow/black)

Thats what it looks like (i think) in the diagram... ?

 

Yes, it isn't difficult

So, 1 will be the NFET SOURCE (S) terminal
2 will be the NFET DRAIN (D) terminal and
3 will be the NFET GATE (G) terminal

Here is a NFET from Radio Shack, that will work for you:

http://www.radioshack.com/product/in...&tab=techSpecs

 

Bob do you have any basic "transistor 101" links - I have a real good base on resistors and LEDs just want to get more practical experience with your basic "using transistors as switching devices" type things. I was reading for a few hours today on jfets and the like.

 

I developed a Semiconductor Structures course that starts out covering how a P-N junction (diode) works, and then progresses into PNP and NPN bipolar transistors, then PFET and NFET transistors. The PFET / NFET inverter CMOS structure is then covered, along with the parasitic bipolar structures, that cause a phenom called "LATCHUP".

PM me your e-mail address, and I'll try and pull some material out and send you. I wrote it as lecture material, not a textbook.

Here are a couple slides from the diode section on half-wave and full-wave rectification:

 

You can probably drill and add another switch in the door jamb like older vehicles used for dome lights. That will take the current too. I bet the factory switch doesn't have a problem, i'd just be a "low" signal to the module. Not sure if thats been covered.

 

Honestly I'd never create a hole in the body like that that will rust just for a mod like this. The trucks electrical system already knows when the doors are opened, its just a matter of understanding the basics I need to to use the sensors that are already there.

 

Smart!

 

well i bought the transistors and I am trying to make it work first on my 12v mini power supply, and I am having no success.

 

just wondering, why wouldnt you want it to come on with the dome light anyhow?

 

Can you draw a diagram on how you hooked it up to your power supply?

The source should go to the NEGATIVE terminal on your power supply, the drain should go to the cathode of your LEDs, the anode of the LEDs goes to the POSITIVE terminal on your power supply. If you tie the gate to the negative terminal, the LEDs will be off, if you tie the gate to the positive terminal, the LEDs will light.

Make sure you have the correct leads on the FET.

 

Yes, this works exactly like you say... but is that the same way it will work in the truck? I was trying to get it to work with simulating a switch of the ground opening and closing (like the truck does)

Your way (with my test stuff) i have to manually touch it to positive and negative and they go on and off.....

 

Bob - you edited your post after I drew this... but..

 

Hey, i dont mean to jack the thread, but my bottom door latch on the pass/rear door is broken and when i make left turns the door a-jar light comes on and then dings. If i cut that yb wire off the rear door will it stop making that ding?

 

Eric --

No, that'll make it always ding. Fix the door latch/switch.

[/end threadjack]

 

Bob - I just have one last question. If I was measuring .7V or so volts with the door closed relative to the hot side of the battery (so it was ~11V like you say) wouldnt this work backwards the way you have it drawn? I mean the LEDs would be on when the door is shut, and they would turn off when I open the door?

I mean before when I was testing my doors in the truck with the meter the yellow/black wire, relative to the battery, would show 12.2V when I opened the door. That would mean that the latch closed the switch right, and it since it was grounded its showing the 12.2V - so if its grounded then it would be like putting the gate terminal to the ground of my power supply, turning my LEDs off.. Maybe I am just overthinking this but the more I think about it the more I think that it is going to work backwards - I might be wrong but if I am please explain.