School Bus Electrical Information

imported_John Whelan - November 16, 2015
We recently found the problem with the no ignition power on one of our pusher school buses. The details leading up to the solution were documented in a previous post. The circuit board has definitely failed because of a bad diode internally that is allowing battery voltage to ground out. This is a dead short which caused the main ignition fuse to blow.

Finding The Correct Information

The schematic is the bible with any electrical problem. You can poke and prod all you want with testing tools but you will have a hard time guessing what the cause is simply because without the circuitry that connects the fuses and relays in this case it would be like being blindfolded. If you don't have the wiring diagram on hand there are many resources you can use.

Get To Know Your Dealer

The dealer wants your business it doesn't matter what kind of vehicle or equipment you own. If they are smart thinkers you will get the information you require. You need to buy parts for your equipment and maybe a new addition to your fleet so it's a no brainer for them to help out their customers. In some cases it may be like pulling teeth but perhaps you might be talking to the wrong person.

We get excellent service from our Freightliner dealer and Thomas Techline people. So when it comes to choosing the brand of bus for new purchases that service is definitely a factor. I don't call them very often only when I'm totally stuck. We want to learn and be self sufficient in our shop to speed up the repairs and have the knowledge needed to keep up. Of course experience (as most people know) is the best teacher in all cases but there are times when things come to a dead halt.

Mechanic Information - Good As Gold

Information like troubleshooting and schematics is like gold to a mechanic who needs that road map to follow eliminating one thing at a time to zero in on the problem. Knowing what goes on inside a component makes life so much easier for the mechanic to understand how it works.

Changing parts just to see if it fixes the fault is risky and a waste of time. It may work occasionally and I'm not innocent from this technique but it's not the best way to operate as a repair shop. Electrical parts are generally not returnable once you open the box it comes in so there is a risk of spending money for nothing.

I know this is common sense speak for technicians out there but it still goes on and for the little time it takes to research proper information. The job will run much more smoothly without a lot of grief. If you could like, share or comment on this post please do so. All of us mechanics and you others out there who work on your own equipment have to stick together.
School Bus