Peterbilt 379 Cruise not working

The Detroit ddec 3 4 wiring schematic pinned at the top of this section shows the brake switch as a nc switch. Maybe you replaced the wrong switch? A scan tool should quickly verify correct switch operation.

 

Would his brake lights [indicators] not be messed up as well?

You do have brake lights that work properly, correct? Stupid question perhaps but easily overlooked and maybe we can rule out a lazy air release or residual air in the system still after pedal release.

 

It's a dedicated switch for the engine. Has nothing to do with the truck lights.

 

Thanks for the clarification.... i stand corrected.

 

So for the third time I mention the brake foot valve. Am I wet behind the ears?

 

Not on the 379.....I am speaking from experience