CM 870 JAKE BRAKES

[Rawze]

first of all ...
JAKE SHOULD NOT BE USED ON ITS HIGHEST SETTING FOR THE FIRST 50K MILES until the head wears in and you do a second overhead valve adjustment. - I HAVE LITERALLY SEEN myself,.. where people have completely destroyed their engines by trying to run the engine brakes on high during wear-in, after a fresh inframe.

Next, as a reminder ...

Its an ISX. Most all of them ONLY HAVE 2 JAKE SOLENOIDS!. One for the front 3 cylinders, and one for the back 3. - The THIRD STAGE engine brake setting simply uses TURBOCHARGER to spool it up hard, supplementing the engine brake strength (seen as up to about 28-psi boost at the intake during braking).


It is actually fairly rare to have a CM870 with 3 engine brake solenoids. Only some of the very oldest CM870's had the 3 solenoid setup, and even then, most did not. Hence there are some factory ecm programs that are meant to drive 3 solenoids. Most all the other factory programs however do not have support for 3 solenoids, and therefore do not use 3 solenoids.

For all anyone knows, you might have a mess on your hands, trying to make a 3rd solenoid work that is not supposed to be there? ...or the wrong program in your ecm for the ser#?.

Also, depending on the ecm part#.. The ecm itself may not even have internal driver support for a 3 solenoid because it is fairly uncommon.