Newell Jake Brakes

[BusNit]

I never felt them work from the day I bought the coach. While I was replacing gaskets for the manifolds, I pulled the valve covers off to check the solenoids. One did not click but all the wiring was in tact like new. I set a tone tester to find the wiring and traced it back to the front fuse panel and a relay. That's all I got up to. Switch in console is either on or off. Today I was playing around with the DDEC scanner and found the engine brake option as n/a. I could not enter that menu to see if I could turn it on or not. At this point I don't know how Newell set up their wiring for the Jake brakes. I spoke to Leo at AAA and he figured there must be an interaction with the DDEC computer to know where the throttle position is. All things seem to point back to the engine computer. I know the previous owner had the ECU replaced at Williams in Phoenix in 2021 just before I bought it. Could they not have programmed the jakes into it?

[luvrbus]

What version is the DDEC ?.a 1993 year model could be a DDEC ll those are not in the ECM it uses a sperate module, The lll forward pickups the signal from the TPS true but on a l or ll with the ATEC 700 series Allision you can pick it up from a pressure switch on the old 700 series 

[BusNit]

It is a DDEC II. HT740 transmission.

I cannot find the elusive module anywhere. Newell did a good job of hiding it

[Iceni John]

My Jakes are controlled through the DDEC II, but just use a cheapo 5-pin cube relay instead of a special module.   The DDEC Engine Brake wire 508 (gray, from the DDEC Vehicle Interface Harness's pin A-1) grounds when the conditions are OK to use a Jake.   It took me a while to understand how my setup works, and when I sussed it out I wrote a How-To to help myself in years to come when I've then forgotten what I learnt!   Here's part of what I wrote:  " When the DDEC signals No Fuel and grounds the Jake relay's pin 85, the relay supplies 12V from CB15 through pins 30 and 87 to the Jake rocker switch.   There is no lockup signal from the transmission  -  only the DDEC signals the Jake."

I also fitted a Jake test/emergency switch that sends 12V to the solenoids regardless of anything else, i.e. the engine need not even be running, and I've used it to hear whether each solenoid clicks.   It can also be used to switch on the Jakes if the cube relay carks, but then I need to remember to switch off the Jakes before the engine returns to idle fuel, otherwise they'll growl very angrily with a risk of burning the exhaust valves.

If you want to make a setup like mine, don't forget to put a diode or resistor between two of the relay's pins to prevent a voltage spike returning to the DDEC, which would be A Very Bad Thing.   I can't remember which pins have them, but they're on the relay's 5-pin connector base, not on the relay itself.

John

[luvrbus]

There are 2 different manufactures of the DDEC ll one has the off/on for the Jakes,he may have the wrong software trying to read his version, as clean as he likes his engine and Newell he may not like the oil spots the Jakes leave on it. The.Jakes with a 3:38 rear gear are not much on a 2 cycle engine till you are in lockup from 3rd to 1st they do sound good .I use a pressure switch and a cube relay on the 700 transmissions ,they are  not going  to stay engaged in 1st gear when you need Jakes coming down switch backs in the mountains unless it is valved for a lockup in 1st gear on the transmission or if the oil pressure gets below 15 psi,FWIW the modules were used to prevent the Jakes from engaging at too high of engine RPM,I hate replacing cams .liners sets, rods and heads on 8v92's because of Jakes   

[BusNit]

I did trace the wire from the solenoids to the upfront fuse panel/relay board. The relay I pulled out is for the jakes. I haven't gone any further in testing yet since the weather has crappy and of course work gets in the way.  Most of my free time has been spent buttoning up the engine and doing an oil change. The rear is a Rockwell axle with 3.72 gearing. Jakes are on/off with no high low setting. Newell does their own thing with these coaches.

[luvrbus]

The low setting (1 bank )are not much anyways ,about like dragging your feet

[BusNit]

I did some wire tracing today. I figured it out and it all leads back to the ECU. Relay gets power when key is on, one wire goes to Jake switch, other wire from Jake goes to ECU and finally remaining wire from relay goes to solenoids. I assume I can't just enable the engine brake feature from my DDEC scanner? in 2019 previous owner had Detroit replace/reprogram their faulty ECU. It is possible they didn't enable the jakes on their programming end?

[luvrbus]

It is more than likely your scanner since it not showing the Jakes ,ECM's are programed by the serial number of the engine when it left the factory they don't miss anything, do your engine tags show Jakes ?

[BusNit]

Engine label shows "Jake see valve mech"

I do have receipts of W.W. Williams replacing the ecu and programming it. Paperwork shows DDECIV which doesn't make sense.

[luvrbus]

Engine label shows "Jake see valve mech"

I do have receipts of W.W. Williams replacing the ecu and programming it. Paperwork shows DDECIV which doesn't make sense.

Williams could have updated the ll to IV it is a common upgrade with more features and faster response ,the PO may have asked for the upgrade ,you got lucky if indeed you have the IV .You may have to go back to Williams and  let Williams put it on the mainframe you are limited what you can do with the Pro/Link code reader ,it not a programmer all you can do is toogle if it is in the perimeters. I have never saw a ll without the module, Van's H-3 Prevost  ll the module was bad and he ran another wire and controls his Jakes with a toogle switch

[BusNit]

I am with you about the module being part of the DDECII but I literally traced the wires and color codes. Could they have done a change midway during the early 90's to output just the ground signal from the ECU? I agree that at this point all roads lead to W.W. Willams where I can plead my case about them forgetting to enable the Jakes when the previous owner had them rebuild/reprogram the ECU in 2019 and paid them some $4900. Yeah, its a long shot with the expectations of them to tell me to pound sand or pay $1200 for them to hook it up...

[luvrbus]

I am with you about the module being part of the DDECII but I literally traced the wires and color codes. Could they have done a change midway during the early 90's to output just the ground signal from the ECU? I agree that at this point all roads lead to W.W. Willams where I can plead my case about them forgetting to enable the Jakes when the previous owner had them rebuild/reprogram the ECU in 2019 and paid them some $4900. Yeah, its a long shot with the expectations of them to tell me to pound sand or pay $1200 for them to hook it up...

Every body I knew at Williams has retired,they were easy to deal with if you had a problem they probably checked 2 dozen ECM's for me over the years and never charged a dime,take the ECM only to Williams,tell the the service guy what's going on and have it checked >My son has a Country Coach with the Cummins engine and has all his work done at Williams