Sunday, February 24, 2013

Special Tool Saves Components When Welding

Protecting Vehicle Components While Welding

This tool (Ultra Pro from Napa) is what we use in our shop and has worked successfully for us for several years (click on photo to enlarge). I was asked what kind of coverage is available if it fails and a component burns out because of it from a high energy surge from welding.

Not sure about that question; I contacted the selling dealer and they have not come up with any answers. The other option is to disconnect the battery ground when welding. The only inconvenience from this is you have to reset your digital components like clocks and timers. Modern School Buses have several modules within the multiplex system and using either one of these precautions is mandatory to save an expensive component from failing.

I have not replaced any modules in our buses yet; the main problem being corrosion to wiring and connections. The connector plugs still get moisture inside in some cases and the use of dielectric grease helps a lot to keep moisture away from the terminals. Oxygen, moisture and electrical current can team up nicely and corrode connections quickly and cause trouble.

A lot of times I have found with corrosion on module connectors there are cross electrical signals that occur and some circuits get energized with constant battery power. We had an instance where 3 different circuits were operating on their own even with the ignition shut off.

With the wiring diagram we were able to determine where the circuits started from and it led us to a corroded connector at one of the control modules. As a preventive maintenance step we have applied dielectric grease to all of the module connectors.


Anonymous said...

i have a tennant scrubber. dont know the year. its a diesel. runs good for two minutes then starts slowing down getting weak and finally shutting off. when i turn it on again it works fine for a few seconds and does the same thing. it will remain on with no load(no scrubbing, squeegeeing or sucking). whats wrong?

John Whelan said...

Not an expert on these models but getting back to basics...I would start with the fuel supply, filters. Is there a load on the engine that idle speed cannot handle? Does it have an engine shutdown system that reads oil pressure and also check the fuel shutdown system..electric solenoid perhaps if it has one?