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Old 06-13-2021, 01:35 PM   #1
Join Date: Jun 2015
Location: Toledo OH
Posts: 103
Year: 2006
Coachwork: Thomas
Chassis: Saf-T-Liner EF
Engine: Cat C7 + Allison MD3060
Turned the key to ON, dash lit up, then cut out, no start...2 mins later, its starts?

Hi all, hard to describe this but I'll do my best.

This morning, I went to drive to Home Depot, turned the key to ON, waited for the WAIT TO START light to shut off, turned on the engine, no problem. Let it warm up a bit, and embarked.

Leaving Home Depot, same thing, no problems.

Made a second stop. Came back out ~30 minutes later, turned the key to ON, waited for WAIT TO START, but then the MD3060 transmission display showed all the LEDs on all at once, then the dash and transmisison indicator went dark and I couldn't crank the engine. Turned the key OFF, then back to ON, same thing. Went outside, opened the battery tray, everything looked good, didn't really touch any wires, closed the tray, went back in to try one more time...dash stayed on, I cranked the engine, it started, no problem.

Definitely experiencing an electrical problem, but I'm not sure exactly what? I removed the back door alarm buzzer and switch last night; only had to remove the assembly to remove the ground connection to the chassis to get it to shut up. There are several other wires associated with the back door that are just "hanging" now, but they shouldn't be getting any ground connectivity given the back panel is painted metal. I will go tape them off to be sure.

I also unplugged the stop sign leads from the strobe module, and pulled the fuse on the strobe module (it has its own fuse).

This is a 2006 Thomas FE bus (see "Ed" in the build threads). Any thoughts other than "trace out all the electrical"? I'm still looking for diagrams that match the current fuse panels, I think they may have been replaced at some point as they don't match the diagrams inside the door at all. Very tidy, but totally unlabeled...
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File Type: jpg 21-06-12 20-04-05 3456.jpg (243.6 KB, 5 views)
File Type: jpg 21-06-12 20-04-13 3458.jpg (194.1 KB, 4 views)

dbsoundman is offline   Reply With Quote
Old 06-13-2021, 02:17 PM   #2
Bus Nut
Join Date: May 2015
Location: Miami, Fl.
Posts: 561
Year: 1999
Chassis: Amtran / International
Engine: DT466E-Md3060
Not really sure if this manual applies to your bus but I uploaded a Thomas manual for retrieving fault codes thru the dash.
Hope it helps you out.
Attached Files
File Type: pdf 92137462-fault-codes-combined-isc-pdf.pdf (1.46 MB, 4 views)
ewo1 is offline   Reply With Quote
Old 06-13-2021, 10:29 PM   #3
Bus Nut
Simplicity's Avatar
Join Date: Aug 2019
Location: Auburn, WA
Posts: 682
Year: 2000
Coachwork: IC / Amtran
Chassis: 3000 / 33' Flat Nose
Engine: IC T444E / Allison MT643
Rated Cap: 72 Kids / 48 Adults
Not sure of your school bus safety knowledge, yet there is so much safety wiring integrated in the starting of a school bus. I had a no crank simply because I forgot to attach a buzzer to ground.

Two suggestions:

1) Put all the electrical back to the way it was and see if the problem continues. If it doesn't happen anymore, then remove one electrical piece at a time and test.

2) This happened to random and so lucky my friend did such a good troubleshooting job.

Definitely have to find the gremlin before moving forward.
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Old 06-14-2021, 07:18 AM   #4
Join Date: Jun 2015
Location: Toledo OH
Posts: 103
Year: 2006
Coachwork: Thomas
Chassis: Saf-T-Liner EF
Engine: Cat C7 + Allison MD3060
I did disconnect the rear door alarm wiring, simply unplugged everything, clipped one wire, then removed the module. I was a little worried that there was a starter interlock, but the bus started normally twice after removing all of that, so I don稚 think that痴 the issue.

Next time I start the bus I値l have my camera going in case this happens again. In the meantime I値l clean up the battery terminals, I think I need new batteries anyway.
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