M-920 "Jake Brake"

[GAR16]

I am hoping someone out there can help. I have a M920, the truck has less than 500 miles on it. I am having trouble with the engine retarder or "Jake Brake". Where or what do I need to check first? Thanks

 

[5tonman1971]

What is your problem? This post is a bit vague.

 

[Floridianson]

I migth start with the micro switch on the PT

 

[WillWagner]

A description of the problem might help out a bit

 

[reb87]

As Floridianson said, the micro switch on the Injection pump(it purpose is to allow jake braking only when the throttle is closed). It can get loose and wont work properly unless the switch is positioned so the throttle linkage compresses the switch when your foot is off the throttle pedal. Also it will be intermittent if any of the electrical wires are loose.

 

[GAR16]

The problem is there is no voltage anywhere. I'm wondering if there is a wiring diagram somewhere I can access it. Thanks for the replies. Steel Soldiers has always been a huge help in the past.

 

[wreckerman893]

There is a wiring schematic in TM 9-2320-283-20-3.

 

[Floridianson]

Yea I would say some power might help.

 

[5tonman1971]

Grab your self a volt meter and start chasing wires

 

[Castle Bravo]

When mine wasn't working, I followed the troubleshooting information in the TM and it led me to what my problem was. My microswitch ("Sensitive switch") was out of adjustment and wasn't getting tripped correctly.

 

[WillWagner]

If it is an auto trans, there should be a switch in the converter lock up port. If that switch is failed, no power to any of the downstream parts. Start there by unplugging the switch and jumping it. The brakes will work without the truck driving. If it's a manual trans, check the clutch switch. Also, maybe start with the CB for that circuit.