I have an issue with the 3rd brake light working intermittently,on a 99 C2 cab.
The pop up spoiler light works all the time when raised. However the light on the Clam shell doesn't wont work consistently, and seems to affect the cruise control as well. Is there a micro switch on the pop up spoiler that is bad and affecting the light on the clam shell?
If I open the Clam shell an inch by activating the top the light comes on,close it it goes out.
I have searched around but no results.

 

Is it the stock third brake light or an LED upgrade?

 

Dennis,
I have LEDs now but the problem existed before I installed the Depo and LED 3rd brake lights.
I have checked at the light itself and the the connector to the Clamshell assembly under the sound or heat insulation. The issue seems too predictable to be corrosion? unless there is a contact block with exposed contacts.(like a slider contact on a minivan side door).
It seems to be related to the clamshell, as I mentioned raise the clam shell an inch light works.

 

Interesting. Most of the problems that I have heard related to tail lights and cruise control are due to LED tail light upgrades. Are you third brake lights LEDs too?

 

Yes, I just installed the (2) LED third brake yesterday, the CC has been acting up for weeks. turns on works most of the time other times the indicator light goes out when trying to activate it.
I have 50W 12Ω load resistors on the signals nothing on the brake,they were included with the Depo tails. I just purchased (4) 50W 6Ω for the 3rd brake lights. I haven't installed then or driven the car since last night.
I changed the flasher relay when the Depo's were installed.
Do I need load res. on the Depo lights too?(Brake circuit)
I guess I can drive around like this? works in this position all the time



Here's the problem when fully closed the light goes out.



found a schematic over on Renntech
http://www.renntech.org/forums/topic...s-on/#entry100

 

Update so I added the 50W 6Ω resistors, one to each and it cured the cruise control problem.

Still have this issue that the main 3rd break light, it works intermittently. If I open and close the top it starts to work