2005 Chevy Avalanche, Cruise cuts out when headlights are turned on

[Walter Szepanski]

I have a strange problem with my Chevy Avalanche.

The cruise does not work if the headlights are on.

Weather you turn them on manually, or if the come on automatically. Can anyone

tell me why, and can It be corrected?

 

[asilverblazer]

I think I would check to see if when the headlights come on the brake lights come on too.

 

(I've heard stories of the filament in the tail light bulb - dual filament bulbs - breaks, falls on to the brake light filament. When the headlights come on, the tail lights come on, the above condition then energizes the brake light circuit which cuts off the cruise control.)

[n4hmr]

Also examine the bottom of BOTH brake/taillight bulbs.  I have had cases where the solder pads on the bottom spread out and eventually make contact with each other.  If this happens as soon as the headlights come on, that will also energize the taillights plus a brake light.

 

The bad bulb then passes taillight voltage to that brake light circuit and the cruise system will think that you hit the brakes.  If any question about a short use a ohm meter to measure across the two solder pads (with the bulbs out of the sockets of course).  If a bulb is good you should read 8-12 ohms or so  (the sum of the two filament's resistance) as you will be measuring the resistance across both filaments through the ground connection (shell of the bulb).  If there is a short you should read 0 (zero) ohms and you have maybe found the problem.