[TR] VTR light guy

[Dave1massey at cs.com]

In a message dated 10/29/2010 4:52:18 PM Central Daylight Time, 
levilevi at comcast.net writes: 
> I bought some and installed them at VTR this year.  I got the tail  
> light/brake light combination 1157 equivalent LED bulbs.  Found out  
> that I can't turn on the tail light/headlight switch on the column of  
> a 71 TR6 and use my cruise control at the same time.  I've got a  
> message into Jim Thompson at LiteZupp but don't think he's back from  
> VTR yet so I haven't heard his diagnosis of this issue.  I'm thinking  
> it has something to do with the brake light portion of the LED bulb  
> and the brake light switch since my cruise is hooked to the brake  
> light switch and shuts off when the brake pedal is touched (just like  
> a real modern car).  I just don't know how it could be happening after  
> looking at the wiring schematics in Dan Masters electrical maintenance  
> handbook.
> 
> 
> The cruise works just fine as long as I don't turn the light switch  
> (on the column on).  If I try to use the taillights it shuts the  
> cruise off just as if I had touched the brake pedal.  Putting the LEDs  
> in was the ONLY thing the changed so it has to be something going on  
> in there that doesn't happened with regular 1157 bulbs.  Both the  
> cruise and the lights work just fine independently but not together.
> 
> Any ideas other than going back to regular bulbs?  I wanted the LEDs  
> mostly as running lights on the highways but the cruise control is a  
> higher priority driving lots of miles and I at least have better brake  
> lights when in traffic and not using the cruise control.  I'd still  
> like both to work at the same time for night time, and rainy-cloudy  
> weather occasions.
> 

First of all, have you verified that the lights still work per normal?  
Check to make sure the gound wires are still attached.  If everything is still 
A-OK then a 100 Ohm resistor in parallel with the brake lights should solve 
the problem.  

LED's behave differently than filament bulbs.  The LED's are in a 
series/parallel combination and the LED's will draw no current until the threaashold 
voltage is reached which coul be 9 - 10 volts.  That high of a voltage can 
trigger the cruise control shut-off function.  

Besides, a guy your age shouldn't be driving at night, old fart.

Dave (old fart)