School Bus Vandalock System No Crank Troubleshooting

I had to post this and share the flaws in the Vandalock systems on both Thomas and international school buses that we have experienced in our fleet. First of all what is the Vandalock all about? The main purpose is to stop bus theft if someone happened to get hold of the ignition key and… Continue reading School Bus Vandalock System No Crank Troubleshooting

Troubleshooting Cummins ISB Diesel Engine Electrical Problems

One of our 2009 Cummins ISB diesel engines died on the road today. It doesn’t happen often but unfortunately on the way home the engine shut down like turning off the switch. Two mechanics went downtown to check it out and tried everything they could to get it going. Priming the fuel system didn’t make… Continue reading Troubleshooting Cummins ISB Diesel Engine Electrical Problems

Thomas School Bus Electrical Problem Circuit Board

I’ve seen a lot of electrical problems over the years and this one is the first with ghost voltage connecting to a relay for the running lights. As described in the video the printed circuit board has all of the fuses and relays mounted on it and connects everything with internal wiring circuits. The LED… Continue reading Thomas School Bus Electrical Problem Circuit Board

School Bus Electrical Troubleshooting

The First Step Troubleshooting Electrical Problems The last month has been unbelievable with waves of electrical problems. Several International and Thomas buses have been coding, not running and not starting on a steady basis. Corrosion is always the enemy and even though the bus manufacturers try their best to keep electrical harnesses and connections sealed… Continue reading School Bus Electrical Troubleshooting

School Bus J1939 Electrical Fault

We happened to have an electrical fault in one of our International buses. The dash registered a large yellow triangle which is supposed to get the driver’s attention and also a message on the dash panel which said “electrical fault”. If you get lucky like we did it was something to do with the ABS… Continue reading School Bus J1939 Electrical Fault

Diesel Engine Diagnostic Software

Diagnostic software for a diesel engine or any engine for that matter is the best tool you can have in your hands. Mechanics need to use diagnostic software to hook up and see what is happening in real time. Viewing the inside information on an engine electronic control unit will give you a time stamp… Continue reading Diesel Engine Diagnostic Software

Diesel Engine Emission Troubleshooting

Note: In this video I said the turbo boost sensor has to be replaced. Now we are cleaning them up with Kleenflo spray or Mr. Clean which works great when you soak the part over night keeping away from the electrical connections. A new sensor costs around 60 dollars so removing soot recycles a perfectly… Continue reading Diesel Engine Emission Troubleshooting

EGR Valve Troubleshooting

We’re looking at an EGR valve on a Mercedes MBE 900 diesel engine. It isn’t working properly as shown in the video using the Mercedes DDDL 7 diagnostic software to check it out. By pulling it off of the intake it’s easy to see the valve open and close. Commanding the EGR with the software… Continue reading EGR Valve Troubleshooting

School Bus Electrical Fault

This is the first time I’ve ever seen a problem like this on an HDX pusher school bus model. The Thomas HDX pusher bus has printed circuit boards that relay all of the supply power to run the lights, heater motors and operating circuits. There are 3 circuit boards in total and troubleshooting requires a… Continue reading School Bus Electrical Fault

Allison Auto Trans Stuck in First Gear

This Allison automatic transmission is a 2009 model in a Thomas school bus that was running around on it’s route when all of a sudden the transmission became stuck in first gear. Past experience with this condition told me that there was something wrong with either the output speed sensor, the connection or the wiring.… Continue reading Allison Auto Trans Stuck in First Gear