Anyone know how to build a timed curcit like the one we have in the Tundra that leaves the cargo light on for 30 secs? I have the undercarriage lights on mine and would like to built a circuit to do the same thing on my wifes 4 Runner.

IHH

I tried to do that for the lights I installed in my toolbox. It is possible but it is very expensive to do. Someone posted some links of parts (timers) to look at but then again I seem to remember that it was around $100 for the parts. I also went to my local elctronics supply store and didn't get any better news there either, still around $100.

If you find something let us know because I would still like to try that mod.

BTW the circuit that has the timer in our trucks for the cargo light and so on is built into one of the major circuits in the ECU I believe.

Herb just a thought but why not tie into the dome light circuit on her car to trigger the on/off for the undercarriage lights. Use a relay so all the power is not pulled from the dome light.

You could do that with a medium sized capacitor and a Diode to isolate the capacitor from the rest of the truck. Like this:


BAT + ----DIODE-----POS CAPACITOR TERMINAL-----POS LAMP TERMINAL

BAT - --------------------NEG CAPACITOR TERMINAL-----NEG LAMP TERMINAL


Sorry the word pictures, hope it makes sense. I'm not sure what size capacitor you would need though, definitley a good sized one, prolly not cheap either.

Wait a minute............

If you hooked the capacitor to a relay instead of directly to the lights, you could use a smaller cap. Relays only draw a tiny amount of power to switch.

I'll keep thinking about it.

-John

A simple 555 timer circuit with a relay would work fine also.

Originally posted by TX_Sequoia
A simple 555 timer circuit with a relay would work fine also.
Can you explain that one. :confused:

Here is some great info on the 555

http://www.uoguelph.ca/~antoon/gadgets/555/555.html

At the bottom you see a timer circuit for Fig 8 "10min timer" could be adopted to how ever long you would like the lamp lit by adjusting R1 (500k pot), they use 10min in this example.

To run other lights (high current) relays would need to be used instead of LED's.

The 555 has been around for ever and has many different uses as you can see. For a simple 1 shot timer it works great.

The problem with the 555 idea is that it is simple. As a Tundra owner, i don't believe that anything should be simple. :D Ha, I kill me.


-John

I read about halfway thru that 555 link. :confused: If I go to my local electronics supply house and ask for a 555 circuit will they be able to give it to me in a package or is this something that I will have to build? In other words do they come pre-built?

The 555 is a pre-built chip. Buy the chip and a IC socket for the chip to sit in, a small piece of circuit board. Just solder the IC socket to the board, then solder the rest of your wiring to the appropriate locations.

-John