rear start/run, accel works - front start/run, no accel

[kjurkic]

Hi all

My new to me bus is a 1994 RTS-08 with DD series 50 and DDEC III.

Have odd problem. Bus drove to parking spot 2 weeks ago, all good.

Now, when I tried to move it:
Rear start/run - accelerator works, but when I turn on rest of system (RUN/LIGHTS on dash) everything works EXCEPT accelerator.
Front start/run everything works except accelerator.

I did notice that STOP (not engine stop) light stays lit whenever front controls turned on. On my other bus, this only lit when applying service brakes.

Truck mechanic I talked to said the the accelerator might be de-activated if the system thinks the brakes are applied.

I have tried lifting the brake pedal and cycling both service brake and parking brake to no avail.

I am heading off to dive back into electrical tests hoping that is it simply the brake switch, but would appreciate any pointers.

cheers
Ken

[lostagain]

Fast idle on?

JC

[Debo]

^^^ This was going to be my question. On mine, if the fast idle switch is on, the accelerator pedal is disabled. Just trying to help...

[brmax]

I have heard from a friend mechanic for the city, these style buses have many more safety switches and pertain to passenger access mostly.
So I am first leaning to doorways open malfunctions and or if the accelerator is just locked out if doors or lowering app's are being used. As I understand they can pretty much use a control module for just these functions and override.
Just my first thoughts, probably couldn't get 2 cents much less bubble gum for them.

have a good day
Floyd

[kjurkic]

Thanks for the input 

Near as I can figure, the wheelchair lift is the villain here. If I kill all power, and shut off the parking brake, I can roll the bus by hand.

I chatted with bus driver acquaintance, and he noted that the lifts are problematic. I am trying to see what I can do to bypass the lockout. I don't need/want the lift anyway. As is, I cannot get the lift to do anything; the control panel will not light up or respond to any of the selections.

From what I understand of the operation, there is an air valve that would keep the park brake on, which in turn disables the throttle. If I can bypass that I should be good to go; or find where the air valve is tripping an electrical switch and cut or splice as required.

My problem is the only wiring diagram I have is for a 1990 RTS with 6V71, not 1994 w/dds50

cheers
Ken

[kjurkic]

Also found old thread here at BCM
http://www.busconversions.com/bbs/index.php?topic=4040.0

But I don't know where the Brake Interlock Rely might be located?

ciao
Ken

[buswarrior]

Find yourself a bus driver from the city who drove these.

All of it may be completely functional, you just need to know the sequences.

That lift in the back doors might prove useful, ever lift a refrigerator into a bus?
There are enable switches at the front must be on, before controls at the back will engage.
position of the high idle has been known to inhibit the lift.

Door handle in correct position - all closed.
Door switches in correct position n - push bar/treadle/exit door
wheelchair lift enable switches at front in proper position
service brake application AFTER all other accelerator inhibits have de-activated

All this convoluted mess is an attempt to design in fail safes when the human at the controls did something stupid.

IMHO, just made the drivers even more stupid, and carelessly apply controls, with the expectation the safety systems will take care of matters.

Active mental engagement with immediate feedback has its benefits...

happy coaching!
buswarrior

[kjurkic]

Hi

Thanks all, found work-around.

By process of elimination located Brake interlock relay and by-passed.

I do not use the lift, and plan to delete it entirely over winter.

cheers
Ken