2010 T660 no jakes

Truck Im running now doesn't have an operational jake brake. Boss said he believes its something in the wiring but hasnt had the time to check into it more. What I do know is the engine and ecm arent original to the truck. Engine is an ISX and I believe its an 05 (yes I know the rules/regs on this). So what Im trying to figure out is if the wiring might be different causing a non-functioning condition before we go looking for a broken/bad wire or other problem. Since this isnt something that would be a dot violation, it gets pushed back behind the other paying repair jobs that are in the shop.

So I figured Id attempt to see what I can diagnose until I can get it back in. So I know I have power at the switch, but I need to check from there to the jakes I suppose. Since Ive never worked on an engine brake, I assume power/signal goes to a solenoid activating the jakes.

Also, out of curiosity would it be possible to "hardwire" power straight to the jakes from the switch, bypassing any ecm involvement?

 

Hmm, I didnt think of checkin that. Good idea.

Thinking about it, my truck will start without the clutch depressed as well. So I'll check that as well.

 

Okay so got a couple minutes to check things out.

So apparently I misspoke and the ISX is equipped with an engine brake, not a "Jake brake".

Had the shop mechanic kind of explain the operation of it to me. What he noted is we have a spliced wire on the harness that doesn't mske sense and the light on the dash doesnt come on even though the dashswitch is illuminated.

So that's where Im at with this. Might try to get the boss to check it out just after xmas to see what we can find.

 

Without taking the dash apart, I was able to hear the switch *click*. The pedal assembly is tight as well.

The harness has a cut purple wire coming off a fuseable link and the spliced in wire seems to be connected to the other end of that purple wire for some reason.

Im gonna plug the serial # into Cummins quickserve and see if I can find a diagram and figure out the pins and what those wires are.