[David]

With the same symptom, that is first speed works but second speed not, the fix was simply to replace the switch on the dash. From memory it was 25 or 30 dollars from Prevost Parts. I’m one of the guys who switch it on each time it’s needed rather than leaving it on all the time. So the contacts probably said ENOUGH!

[Rudy]

This is just a general comment that might apply to all Jake brake equipped coaches.

Prevost has two terminals in the rear electric box that supply power to the Jake brake solenoid valves that are under the engine valve cover. There is a way to help isolate the problem when the Jake is not functioning or is only partially functioning.

The terminals are listed on the chart showing the electric box. If the engine is idling, and a jumper feeds power to each terminal one at a time you will hear the engine lug down. What you are doing is powering the solenoids directly and verifying they are doing what they are supposed to do.

If the engine does not lug down when power is applied to the Jake terminals then there could be a problem with the solenoids or the wiring to the solenoids. If the engine does respond by lugging down the reason the Jakes are not working is elsewhere. If a mechanic wants to change the solenoids in the engine without testing as described above he is just guessing and spending your money. BTW, the problem if it appears to be in the engine can be as simple as a disconnected terminal or broken wire.

[Dan]

Derrick,

I returned your email regarding your Jake brake. We discussed this with Bill Jensen at the seminar just to make sure we were correct in telling you that you do in fact have a 2 stage Jake. Your button should have 3 positions, off, 1 & 2. Position 1 uses 4 cylinders and position 2 uses 6 cylinders.

You’ll just have to find someone who can diagnose the problem as Jon pointed out.

[Dan]

I just had work done at the DD/Allison dealer in Ocala, Florida. Part of the work was the diagnosis and repair of my non-functioning Jake brake. The techs seemed to have extensive knowledge about Jake brakes. They did a good job, and they do not seem to dislike working on Prevosts.

I understand that you are on the other side of the country, but if you head this way, I recommend them.

[Dick]

Thanks Dan, We changed it at the same time we changed the solenoids. I taking it to another Detroit guy today, we’ll see.

Thanks again

Derrick

[Archived]

Thanks Jon, learned this the hard way, changed solenoids and the old ones were fine. Going to another Detroit Dealer for computer program work today.

Thanks Jon

Derrick

[Archived]

Thanks Colt, I wish I was heading you way, maybe January.. Thanks again.

Derrick