Jake Brake-8V92 DDEC II

[Sam 4106]

Hi All,
I would like to get the Jake brake working in our MC 8 with a 8V92 DDEC II before our trip to Arizona next month. I have a copy of the schematic but no idea how to even begin checking for the problem. Any guidance would be appreciated. Do I have to take it to a shop where they can plug the engine into a computer ?
Thanks, Sam 4106/MC 8

[luvrbus]

Sam, do you have the electronic transmission if so it has to be tied to the ATEC ECM if I remember it is wire # 213 if you have a manual transmission you need to check the clutch switch .
1st thing I would check would be the power supply to the off - on switch



good luck

[RTS/Daytona]

Sam

Send me your addy via the Personal Message or via my email addy in my profile

and I'll send you an electronic copy of the --->

DDEC-II Jake Brake Trouble shooting Guide #021772

Pete RTS/Daytona

[Sam 4106]

Hi Luvrbus and Pete RTS/Daytona,
Luverbus, my transmission is an Allison HT 740 so there is no electronics between the engine and transmission that I know of. The switch is a three position with OFF, LOW and HI. I will test for power to the switch in the morning.
Pete, I sent you a PM and look forward to getting the trouble shooting guide.
Thanks to both of you, Sam

[Sam 4106]

Hi Guys,
I had no power when I tested at the switch this morning so I went to the front electrical compartment and started at stud 65. I had power there so I went to the circuit breaker and had power there. Then to the relay and had power to the input but not to the output. The input to the relay is also the hot for the coil. The ground side of the coil is wire 508 that goes to the DDEC II ECM and there is a note on the wiring diagram saying that "CKT 508 - SIGNAL RETURN - IS GROUNDED IN THE ECM WHEN THE ACCELERATOR IS RELEASED".
The screw holding wire 508 was very loose so I suspect that is the problem. I didn't get to take the bus for a test drive today because of other work being done nor did I start the engine because I didn't want to smoke up my shop. I plan to test drive this weekend.
The trouble shooting manual Pete RTS/Daytona sent me gave me enough guidance, even though the wiring diagram is different than mine, to figure out the problem. Thanks, Pete.
Thanks for the help, Sam