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HolidayBus
Active Member

12 Posts

Posted - 01/04/2019 :  09:51:37 AM  Show Profile  Visit HolidayBus's Homepage  Reply with Quote
Hello,

I have a 2008 Thomas school bus it is a front engine flat nose. I am having troubles with my stop sign. When I turn on my 8-ways it will not come out. The switch tells all the nights to come on and flash just no movement from the stop sign. If i pull it out manually to see if it will close itself it will.

Here is what i have checked so far. Some of its overkill but just to be safe I did it.

8-way controller box is works
Motor works
Micro switch box works
Actual 8-way switch works
Fuses are all good

I'm thinking next step is going to be tracking down the wiring but I just wanted to see if you guys had any ideas?

Cal Mc
Advanced Member

303 Posts

Posted - 01/04/2019 :  1:01:49 PM  Show Profile  Visit Cal Mc's Homepage  Reply with Quote
the wiring to the stop arm is fairly basic.
Red- power supply
Blue- trigger wire
Ground- I have seen various colors depending on manufacturer

If the stop arm is returning when you shut down the red lights you have power and ground.
When the red lights are operating and you pull the stop arm out and it stays out until you shut down the red lights, the arm is receiving the trigger signal on the blue wire.
Have you tried changing the two relays inside the stop arm?
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HolidayBus
Active Member

12 Posts

Posted - 01/04/2019 :  1:47:53 PM  Show Profile  Visit HolidayBus's Homepage  Reply with Quote
When the red lights are operating and i pull the stop sign out it doesn't want to stay out it just wants to back in.

My stop arm has no replays in it but the fuse panel has one and it is working.
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buster133
Top Member

USA
512 Posts

Posted - 01/04/2019 :  4:51:31 PM  Show Profile  Reply with Quote
Is this a Specialty or Transpec branded stop arm? Check this link for troubleshooting info

https://busandrail.safefleet.net/resources/technical-support/

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Bluenozer
Top Member

Canada
640 Posts

Posted - 01/08/2019 :  03:26:56 AM  Show Profile  Reply with Quote
Found this with thomas carolina site not sure if this is for your model year

Do NOT disturb any wire connections for these tests as
interrupting 12V power to the stop arm relay can cause an
intermittent failing relay to start working. We feel the relay
has an intermittent issue and are working diligently to prove
this.
THESE TESTS ARE CONDUCTED WITH THE KEY ON.
Step 1: Access the relay by opening access cover behind stop arm
blade. Test the red input wire from fuse for full battery voltage
(+12V) at the wire. If no voltage check fuse at PDM. It is marked Stop
Arm and located in the switch cabinet.
Step 2: Test the white ground wire at the relay for good ground at the
wire by doing a voltage ground test with digital multi-meter.
Step 3: Activate the 8-light warning system and check the
blue wire at the relay for full battery voltage (+12V) from the
Chassis Hub Module (CHM). If no voltage check fuse at CHM
fuse panel. It is clearly marked.
Also, check for 0-Volts when the warning system is
deactivated. If 0-Volts recorded and lights are on, the relay is
bad.
Step 4: If any of the previous inputs are incorrect, check the
wiring leads to the stop sign lights for breaks or shorts. You
can activate the system and move the wire loom to stop arm
blade back and forth to see if you can get lights to fail due to
a bad loom.
Step 5: With all three correctly functioning inputs,
check that there is 0 volts on the output wire to the
stop arm blade lights with the warning system
deactivated.
Step 6: With the warning system activated check
that there is constant battery voltage (+12V) on the
output to the lights on the stop arm blade
Step 7: If all of the above checks are OK the lights or light wires to stop arm blade are probably at fault.
If steps 5 or 6 do not check out as described the stop arm relay module is at fault.

OEM trained in wiring and all engine platforms for over 20 years
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HolidayBus
Active Member

12 Posts

Posted - 01/10/2019 :  12:53:58 PM  Show Profile  Visit HolidayBus's Homepage  Reply with Quote
Went through the wiring again and behind a panel my trigger wire was disconnected. Reconnected it and it works good now. Thanks for all the help!
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