Clutch switch

Look at the top of the clutch pedal. There should be a switch with a skinny 2 or 3 inch spring. It looks like this

 

If your clutch does not touch that spring, your cruise and jakes won t work

 

In order for the ECM to activate the Jake brakes, it needs to see the clutch switch is closed and the pedal sensor is at minimum. Basically, if they are not the ECM thinks the drivers foot is on the clutch or throttle pedal and will not allow the Jakes to work. That also includes the cruise control not working either.

Might want to check to see if the clutch pedal is extending all the way back and hitting the switch. Sometimes the spring gets weak and won't hold it against the switch.

 

I know on my KW's the clutch switch is a little different then what you showed. The switch I have has a little rod with a mini wheel that sits on the clutch peddle if I remember right. I imagine every brand of truck uses different switches?

 

It looks similar to the one Penske replaced on my Cascadia

 

Pull the clutch pedal up and see if the jake works..... Just for the fun of it.

 

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It doesn't cost a lot to replace like 150$ are something like that

 

if you pull up on the prdal with your toe and your jake/cruise works its probably an adjustment, you can change it yourself easily for about 30 bucks and 10 minutes.