Thomas Rear Engine School Bus Electrical Troubleshooting

Electrical troubleshooting can be a breeze once you know the layout. It’s much like any blueprint that details the operating system. With this Thomas HDX rear engine pusher model the engineers were very kind developing an easy to use electrical circuit board system that offers the details of each board on the access door. I’m… Continue reading Thomas Rear Engine School Bus Electrical Troubleshooting

Thomas HDX School Bus Road Test

I would like to follow up on this video. We changed the surge tank low coolant sensor and that fixed the problem with alarms and dash lights coming on. This problem did not happen all of the time. It’s a phrase used a lot in the mechanic world known as “an intermittent problem”. These are… Continue reading Thomas HDX School Bus Road Test

Thomas School Bus Diagnostic Link 8 Software

Thomas school buses along with Freightliner highway trucks have multiplexing software built in to reduce wiring and connections. It’s similar to optic cable where messages are flying back and forth at high speed. To make all of this work there are several modules that interconnect with J1939 to relay inputs and outputs. if the operator… Continue reading Thomas School Bus Diagnostic Link 8 Software

Thomas Pusher Mercedes MBE 900 Emission Maintenance

It doesn’t matter who you talk to preventing problems is natural. Prevention is a big word when it comes to anything mechanical that runs on wheels. This 2007 Thomas rear engine pusher school bus is going through several repairs. The diesel particulate filter needs cleaning because of an engine code which indicated that there was… Continue reading Thomas Pusher Mercedes MBE 900 Emission Maintenance

Diesel Engine Cold Start in a School Bus

This diesel engine in this video started up quite nicely compared to other buses I’ve encountered during winter conditions. The batteries were in good shape and there were no mechanical issues with the fuel system. So what could cause a poor start on a diesel engine? First thing is block heaters or diesel coolant heaters.… Continue reading Diesel Engine Cold Start in a School Bus

School Bus Garage Machining Brake Shoes

School buses are fussy sometimes so fine tuning is required once in a while. In this case the front brakes were grabbing and pulling the bus to one side at slow speeds. The best method to repair this problem is machining the brake shoes and brake drums. It’s not a unusual step to take in… Continue reading School Bus Garage Machining Brake Shoes

Mercedes MBE 900 Diesel Engine Repair

This repair has a long history of scenarios which ended up as a major engine repair. The head gasket on this 2008 Mercedes MBE 900 diesel engine has failed. That’s the least of possibilities. Another option would be a cracked head but I’m staying optimistic. One thing for sure the top end of these diesels… Continue reading Mercedes MBE 900 Diesel Engine Repair

Cummins ISC Diesel Engine In School Bus No start

The Thomas HDX school buses we have in our fleet range from years 2007 to 2009 and one fault that has been happening lately is either a no start or no run condition. Of course as always everything happens in groups of three. There was a no start a couple of weeks ago that required… Continue reading Cummins ISC Diesel Engine In School Bus No start

School Bus Short Circuit

In the video you heard the fuse that was popping off every few seconds. That is a short circuit or more commonly called a ‘dead short’ directly to ground. The fuse resets itself so it’s handy to have that plugged in so we can check wiring exposed around the printed circuit board where all this… Continue reading School Bus Short Circuit