Does anyone know why the instuctions for the cummins jake brake has you tap and splice to two pins on bus (b) on ecm??

Kind of nearvous about this part of install!!

What are the pin locations? You can download the sevice manual from the "merry christmas" thread up top of this forum.

I will look them up i think it has some thing to do with the increased trans lock up for the brake , it says it re calabrates trans for increased braking and downshifting but it dont have a trans commander box so its got to be what its for.

I am looking at the pin out diagram for the "B" ecm plug there are several trans related pins on this plug.

I think the previous poster said it right. The connection is to tell the tranny to keep the TC locked. Normally when you lift off the accelerator completely, the TC unlocks so the vehicle can come to a complete stop. If you tried to stop the vehicle with the TC locked, it's like trying to stop a standard tranny without steppin on the clutch. Motor stalls or something breaks.....lol. The engine brake probably keeps the TC locked until the speed drops below 18 mph, or in that area. It may also keep the TC locked through downshifts even into second and first.

If the TC were to be unlocked during exhaust braking, the amount of physical braking power is reduced because the engine and tranny are coupled only by fluid, not by a lockup clutch. Once the lockup clutch is engaged, the braking effort increases considerably.


Now did you install the 60lb exhaust valve springs? I hear the brake is worthless without them. Just curious, not breakin *****.


Good luck with your ride

Yup did some readin up on it and you appear to be right the connections are for the lockup control.And to answer the spring question the 06 has 60lb springs already installed from what i was told by cummins.

I thought those were for the 12valves and that they were 90lb springs. I haven't seen any for the 24 valves.

Dont know i will start thred and see if drew or anyone else knows.