I’ve got a 2006 Mack CHN 613 with a E7 engine. I was told before I bought the truck that the engine had been replaced with another used engine because a rod had went through the side of the block. And when I was doing the maintenance to adjust the valves and removed a valve cover I noticed it has an engine brake on it, but there was no switch on the dash. According to the VIN it did not come out with an engine brake, but when I opened up the dash there was an empty pigtail marked engine brake so I bought a switch and hooked the switch up. It lights up like it works, but the engine brake does not. Is there any way to make it work or is it a totally different wiring harness?
