turn signal, brake priority relay setup

Gentlemen,

Hotwaterwizard: I was not able to get the circuit you described to work the first time without the diodes.  I was just on vacation so I've been out of touch for the last week.  I will try using the diodes just to play. 

Dualsport: The XOR type circuit works great.  You're right, it really doesn't need diodes.  When voltage is present, the relay will react to keep discontinuity. 

I find this trial a sucess.  It is great this info can be available for folks to build for themselves, get to know (maybe) electricity a little better and appreciate what its worth.  This simple circuit can be bought in a camper/trailer type store, but the deal was like $30+ dollars.  Through the use partsexpress.com, I was able to get all the necessary pieces for less and build it myself.  I also get to know my car a little better, too.

I have decided to use the circuit described by Dual Sport.  I was able to put the circuit together and try it out on the van.  The circuit works just like it is supposed to.  However, I found out that when brake and turn signal are on simulataneously, the flash rate of Blinker is too fast.  This makes sense because the T/S (Turn Signal) input only operates the coil of the relay for brake input.  During this condition and only this condition, the T/S flasher up front reads this as load missing at the rear, the relay coil impedance must be very small. 

To defeat this, I figure putting a resistor in the circuit matching the rating of the bulb.  The bulb is rated 27 Watts, at full voltage (14V).  The resistor to match the 27 watt rating would have to be fairly large according to some website data.  I put some thought into, the T/S is not on continuously but in a flash condition.  My question is, could I get away with a lower wattage resistor (say 10W?) knowing the load will not be continuous?  Without getting into too in dept with the flash rate, amount of time the resistor will sees load off and on yield a value suitably less than the bulb specification.

Any thoughts?

The only problem with that method is that this vehicle has onboard control modules.  I was not able to find a flasher box anywhere.  Then I reviewed the repair manual it does not list a flasher relay but an integrated control module, ICM or sometimes called the BCM.  The way this van was designed rules out option 1.

Do you really think it will get that hot with the on and off operation?  If the resistor were to be powered on continously, then yes with no doubt fear of the heat issue.  It has been on my mind, too,  just to wire the same lamp in place of the resistor.  The same lamp held in my hand with cloth on the glass does not get hot while flashing....

Spent hours figuring mine out.

No thank you just negitive remarks.

hotwaterwizard:

I do not know of any negative remarks by me.  And I mean to the nature of hurting your feelings.  I was not able to get the circuit you illustrated to work on my bread board and stated my findings.  In no way shape or form am I questioning your ability to create and invent circuits for different applications.  I thank you for your efforts, I spent several hours testing this stuff as well.  Sorry for the delay.

I figured out that I shouldn't post anything before I drink my morning Coffee.

Sorry not quite awake yet.