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05-03-2015, 10:07 AM
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#1
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Skoolie
Join Date: Apr 2015
Posts: 205
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2000 GMC Microbird Electrical questions
I might be an old mechanic, but I'm new to school bus's.
I just bought a 2000 GMC Micro Bird 19 passenger and it has a couple electrical ... gizmos ... that I don't know the first thing about.
Hopefully, y'all might be able to help me identify some of this stuff. See the pictures below.
The "Merlin" box has a number of lights/buttons on it. they are labelled: CPU - Txd - Rxd - Cor - Ptt
I don't have a key to open the large black box by the door. There are no labels or markings on this one, but, there is a number of wires going into the back of it.
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05-03-2015, 10:10 AM
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#2
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Bus Geek
Join Date: Aug 2011
Location: Stony Plain Alberta Canada
Posts: 2,937
Year: 1992
Coachwork: Bluebird
Chassis: TC2000 FE
Engine: 190hp 5.9 Cummins
Rated Cap: 72
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That stuff is all not needed.
It should have been removed by the school division before the bus was sold.
I would trace the wires back to the fuse box, and remove it all.
Nat
__________________
"Don't argue with stupid people. They will just drag you down to their level, and beat you up with experience."
Patently waiting for the apocalypses to level the playing field in this physiological game of life commonly known as Civilization
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05-03-2015, 10:11 AM
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#3
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Skoolie
Join Date: Apr 2015
Posts: 205
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Since I'm new to bus stuff, I would LOVE to get a wire diagram for the GMC chassis AND one for the Bluebird coach body. I am assuming that they are separate.
Any suggestions where I might look for these things?
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05-03-2015, 10:14 AM
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#4
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Skoolie
Join Date: Apr 2015
Posts: 205
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Quote:
Originally Posted by nat_ster
That stuff is all not needed.
It should have been removed by the school division before the bus was sold.
I would trace the wires back to the fuse box, and remove it all.
Nat
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Hey Nat,
I was pretty sure I didn't need it and planed to remove it. I'm just curoius to know what this stuff is (was).
Thanks!
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05-03-2015, 10:14 AM
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#5
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Bus Geek
Join Date: Aug 2011
Location: Stony Plain Alberta Canada
Posts: 2,937
Year: 1992
Coachwork: Bluebird
Chassis: TC2000 FE
Engine: 190hp 5.9 Cummins
Rated Cap: 72
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Quote:
Originally Posted by Tedd
Since I'm new to bus stuff, I would LOVE to get a wire diagram for the GMC chassis AND one for the Bluebird coach body. I am assuming that they are separate.
Any suggestions where I might look for these things?
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Good luck.
Most buses wiring will change from bus to bus.
I would just trace the wires back to what ever is in question.
Nat
__________________
"Don't argue with stupid people. They will just drag you down to their level, and beat you up with experience."
Patently waiting for the apocalypses to level the playing field in this physiological game of life commonly known as Civilization
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05-03-2015, 12:52 PM
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#6
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Bus Crazy
Join Date: Jan 2008
Location: Adirondack Mountains NY
Posts: 1,101
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Pic # 1 is probably a video camera. The dark circle in the middle looks like a lens.
Pic # 2 is for a radio data link. I don't know the brand, but it either is a modem to connect to an external 2-way radio, or it is an integrated modem and radio package. I could tell you more if I could see the back connectors.
If you don't want this, I would like to take a look at it. PM me for an address and I will reimburse you UPS or USPS ground shipping. If you don't want the camera, toss that in.
CPU - usually a "heartbeat" LED. It should flash every few seconds to confirm that the internal software has not crashed.
TxD - transmit data - when this lights, the bus is sending out information.
RxD - receive data - when this lights, the bus is detecting another data signal of the same format coming in
Cor - an old term left over from tube-type radios. It means "carrier operated relay." When this lights, it means the radio squelch has opened because the channel is busy. The "carrier" it has detected is not necessarily data (see RxD), it could be a voice transmission or just some interference. The Cor on a modem like this is used to delay a transmission from the bus until the channel is clear.
PTT - "Push-to-talk," a term for exerting a transmit command that is based on using the button on the side of a microphone. When this is lit, the bus transmitter is on the air. The data (TxD) might be delayed after the PTT to be sure the radio and modem on the other end are ready to receive.
Picture #3 is a vault for a video recorder to store the pictures from the daily run. Some districts have less recorders (or cameras) than buses, they rotate them through the buses as a psychological deterrent. The kids (and maybe the driver & monitor) never know which days they are being taped, and which they are not.
You could drill the lock and replace it with your own so you could have a place to store valuables.
__________________
Someone said "Making good decisions comes from experience, experience comes from bad decisions." I say there are three kinds of people: those who learn from their mistakes, those who learn from the mistakes of others, and those who never learn.
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05-03-2015, 01:49 PM
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#7
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Bus Crazy
Join Date: Jan 2008
Location: Adirondack Mountains NY
Posts: 1,101
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I found the Merlin on a search. I thought the case looked familiar. It is made by Pyramid, a company that makes boxes that let cops & firefighters operate their mobile radios from their handhelds when out of the vehicle.
The Merlin is one piece of an Automatic Vehicle Location suite of products. The box does not include a radio, but does include a GPS chip that feeds position data to the modem. The Merlin can be programmed to "snitch" the bus's location when connected to a radio in one minute steps between one minute to 4 hours.
It also has 3 status inputs. One could be wired to report when and where each time the passenger door was opened, for example.
The inputs can be combined and wired to a "Mayday" button. One input's function can be programmed to change the location report frequency to steps of 5 seconds instead of one minute during an emergency (bus-jacking?).
You would need external equipment and software to make use of the location information that the unit transmits.
__________________
Someone said "Making good decisions comes from experience, experience comes from bad decisions." I say there are three kinds of people: those who learn from their mistakes, those who learn from the mistakes of others, and those who never learn.
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05-03-2015, 02:27 PM
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#8
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Bus Nut
Join Date: Feb 2015
Posts: 258
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Radio Engineering's Bus Watch can also be found online. It's basically like an aircraft Black Box but for buses. A lot of bus companies are installing these now for legal liability or insurance reasons.
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05-03-2015, 06:08 PM
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#9
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Bus Geek
Join Date: Aug 2011
Location: Stony Plain Alberta Canada
Posts: 2,937
Year: 1992
Coachwork: Bluebird
Chassis: TC2000 FE
Engine: 190hp 5.9 Cummins
Rated Cap: 72
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We throw a ton of these black boxes in the junk pile. I use a few at the shop for tool boxes. They remind me of a ammunition can from the army.
Nat
__________________
"Don't argue with stupid people. They will just drag you down to their level, and beat you up with experience."
Patently waiting for the apocalypses to level the playing field in this physiological game of life commonly known as Civilization
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05-03-2015, 07:07 PM
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#10
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Bus Geek
Join Date: Apr 2012
Location: So Cal
Posts: 3,231
Year: 1935
Coachwork: Superior
Chassis: Chevy
Engine: 317 ci/tid / Isuzu
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Thanks for all the info Redbear. I appreciate it and I'm sure Tedd and others do as well. Working or not it might serve as a theft deterrent even if not hooked up--but then I'd prefer a claymore hidden just under the beaded seat cover on the drivers seat. Just saying.
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05-04-2015, 08:56 AM
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#11
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Skoolie
Join Date: Apr 2015
Posts: 205
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Thanks so much for the all help!
I took a couple moments, followed the info you gave me and spent a little time looking this stuff up. I even found installation and set-up user manuals for some of it.
As I like to tell the younger mechanics, The first part of disassembling anything - is to figure out what kind of NUT you're dealing with.
Thanks again for the help.
T
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