Getting Jakes Working

[Glennman]

I just got my bus back from a local mechanic who was trying to troubleshoot my Jake brakes. From a previous post, I had mentioned that the bus is equipped with Jake brakes but they had never been hooked up. The wiring harness is there, I installed an OEM switch, nothing. So, I took it to a local mechanic and he determined that even though the ECU has the Jakes turned on, the multiplex system is not set up for them (schematics say "not used"), and he concluded that I would need to take it to MCI to get them working, which is out of the question.

That being said, I'm going to be installing a wire run from the dash to the engine and he is going to come out and hard wire the Jakes. The problem is that due to the direct hard wiring, the transmission, brake pedal, fuel pedal etc. will be excluded from its function.

With the research I've conducted, I would need to operate the Jakes in a "manual" fashion. That would include monitoring my RPMs keeping them between 1500 to 2000 RPM, I would need to tap the brake or downshift the transmission (and continue to watch RPMs) to a lower gear (4th gear for instance) and not apply fuel while Jaking. I cross over White Pass here in Washington quite a bit and I need to hold my speed to 25 MPH because the westbound direction is pretty steep for quite a distance. Other passes we've been over is Lookout Pass, 4th of July Pass and Dead Man's Pass, which can be a real brake burners.

My plan is to only use the Jakes when crossing over passes like those. Otherwise, they will remain off. What do you people think of all this? By the way, my new mechanic is great. I was introduced to him through jbnewman who was in the Yakima area picking up a 4106 bus. He is very knowledgeable and it turns out that we knew him years ago. While he had the bus, I had him replace my valve cover gaskets, cam seals on the ends of the engine and give the engine and other systems a good look over. It's great to have someone local who is willing to work on it!

[luvrbus]

That will work for you just be careful the 60 series get ugly with rods through the block ,me I would wire the switch to the brake lite switch with a relay so it only had power with a light touch of brake pedal to activate the Jakes . Have you tried Diesel Control (DCS) in Cheswick PA and asked him what is causing the problem? with the b500 and series 60 you have a communication glitch some place ,your plan will work       

[Glennman]

That sounds good luvrbus. When I do use it, I will only be going about 30 mph. When I drive down from White Pass here in Washington (heading west) I keep the bus to about 25 to 30 mph. However, it's all brakes and transmission. I plan to continue to only go about 30 mph, so it's not like I'm going to flip the Jake switch doing 65 mph. My plan is only to maintain a slower speed for those steep grades using the Jakes in conjunction with brakes and transmission, and keeping my RPMs lower. We'll see!

[Glennman]

Well, so much for that. The mechanic was out for 6 hours installing relays and fuses, etc. However, he could not get it to work so that the fuel would cut off when the Jakes are engaged. He may have been able to do something with it, but he would have to shift gears after working on it all day. He's thinking I could have a problem in the ECU. I plan to get a spare ECU. He said to have it table tested for the Jake operation, and that just because they may be "turned on" in the ECU doesn't mean that there isn't a problem after that. So, for now it's back to the drawing board.

[luvrbus]

Better check the ECU on the b500 ,the ECU on a B500 has a setting that has to be in the enable mode for the Jakes to work you may have the saddle on the wrong horse here, there is a setting for the Jakes, drive it to Allsion and see if it is on or off, The B500 has a mind of it's own it doesn't care what the engine says 

[Glennman]

Thanks again luvrbus. I've been at the beach for a few days, so I haven't been following the board.