Warning Light/Buzzer Wiring Diagram

[colecruzer]

Hi,
I am installing new gauges, wiring, warning lights and engine sensors on my 79 MC-5C (6-V71 Detroit).  Does anyone have a better wire diagram than the original plan that dosent require the use of diodes.  Thanks for your help.
Rich

[gus]

Rich,

After many hours studying the original diagrams for my 4104 I decided that the old diode based warning system was so complicated by numerous wiring changes over the years that it was far better to just wire around the old system instead of trying to make it work.

[bevans6]

What the diodes do is allow several warning signals to use one buzzer for the audible alarm.  They prevent the signal from one sensor to backfeed into the other sensors.  they are just electronic check valves, basically.  If you don't want to use them, you have to change to sensors for your various things you want to monitor that can't be harmed by the back-feed voltage, and lose the ability to have a light and a buzzer (without the diodes all the lights will go on at once when any alarm is triggered) or just go with several buzzers each on a unique circuit.  All the diodes do is let you get away with only one shared buzzer at the end of the day.  Just think of them as one-way check valves.

Brian

[Len Silva]

Brian beat me to it but here is a simplified diagram of what he was saying.

Len

[Dreamscape]

Brian and Len, Good job on the description/purpose, even I understood it! Now that I've learned something today I can take my nap!

Paul

[colecruzer]

Brian,
Where can I find these diodes, how do you determine the rating I would need and how would they be connected into the wiring?
Thanks,
Richard

[pvcces]

Richard, I would think that the 4000 series diodes at Radio Shack would be plenty skookum. They just have to be able to handle signaling current, which doesn't amount to much.

Tom Caffrey

[bevans6]

The stock diodes on my bus are stud mounted, which means one terminal is actually a 1/4" or 3/16" threaded stud that you fasten to a buss strip with a nut and lock washer.  the other end is a solder terminal.  I needed one and just bought it from MCI here locally, probably paid 1000% too much compared to shopping around at electronic supply places, but it was cheap anyway.  the shipping to my place cost more than the diode.

They are used all over the bus for various things, the one that broke (physically broken not electronically failed) on my bus that I needed to replace was part of the drivers heat switch, the low speed setting.

Brian