"Stop Request Relays" What are They?

[Depewtee]

Hi All -

I have been "thinning" out the wires located in the electrical panel outside the driver's area of my 1984 MCI MC-9.  My thought is that the more wires I remove now, the better chance I will have at troubleshooting electrical problems later.  Obviously, converting from a transit  bus to a coach has left many of the wires without any current use (wasn't trying to be punny).  Some wires seem obvious choices to remove, while others I am not sure about.  I have the maintenance manual, but it is really not much help when it comes to sorting out the wires.  Anyway, I have stumbled across two relays identified as "Stop Request Relays."  Was there some type of system in these buses for the passengers to alert the driver they wanted to stop?  Sort of like a flight attendant call button on an airplane?  Or, are these relays (there are two of them) part of the stop light system?


Thanks in advance,
Brian S.

[Sean]

"Stop Request" universally means a system to signal the driver to stop, activated by pull-cords or pressure strips from the passenger area.  On many coaches, it also illuminates a sign visible in the passenger area indicating that a request has been made.

If your coach was equipped with a stop request system, it will have either pressure strip switches or momentary pull switches, as well as an indicator light and buzzer in the dash area.  There may also be a switch to "cancel" the request.

I'm sure others here are more familiar than I with the specific system fitted to MC-9's destined for transit service, although I suspect many details are specific to which line ordered the coach.

-Sean
http://OurOdyssey.BlogSpot.com

[Depewtee]

Hi All!

An update on the Stop Request Relays question....  Based on Sean's post and my initial impression that these relays were part of a system designed for passengers to alert the driver, I removed the relays and most of the associated wiring.  Three wires were part of a harness that terminated on a bus bar located in the spare tire compartment (mounted nearly dead center on the ceiling of the spare tire area).  There was a similar wiring harness leaving the bus bar and going toward the back of the bus.  Anyone know where this harness might terminate?  It seems it would come in handy for making connections from the back of the bus to the front - the wires appeared in good condition.  By the way, I have not noticed anything that is not working since removing the relays.

Thanks,
Brian S.

[Chuck Newman]

The electrical panel accessed from outside the driver area is termed the "front junction box".  The "rear junction box" is in the engine compartment on my 102.  Probably the same on your 9.  I have a MC-9 maintenance manual and it has very good easy to read electrical diagrams, but they are fragmented.  My 102 diagram is harder to read but has everything on one very large sheet.  I find things easier to trace with it all together.

The 102 has several "spare" wires that run from the front to the rear junction boxes.  Probably the same on your bus.  Note you also have a "A/C junction box".  Mine was on the top of the first bay.

Be careful when removing wires.  I always referenced the diagrams and check wire numbers.  Sometimes a power wire will feed a second or third item not obvious when tracing it visually.  I recommend removing a wire or two at the most and then check that everything still works.  

Chuck