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Bus Discussion => Bus Topics ( click here for quick start! ) => Topic started by: kemo3ce on January 29, 2015, 08:11:55 PM

Title: Welding h3-45 info
Post by: kemo3ce on January 29, 2015, 08:11:55 PM
Ok I have a bracket that's coming off, I need to weld it. My question is what must I disconnect? I know on a car the battery so I assume the batteries on the bus.. But the equalizer and charger too? I'm assuming yes to everything but I wanted to ask to make sure.
Title: Re: Welding h3-45 info
Post by: eagle19952 on January 29, 2015, 08:45:45 PM
it depends where you attach the ground lead, and how many amps ...i would disconnect any ECM at a minimum, i might even remove it entirely.
i have welded a ton of things without disconnecting the battery/ies.
Title: Re: Welding h3-45 info
Post by: B_K on January 29, 2015, 09:27:22 PM
I have always been told to unhook any batteries, ECM, TCM (trans control module), aand any other computer on board before welding.

Some say you don't have to go to all that trouble.
But they are not the ones dishing out the $2500-$5000 if one blows either!
I just do it to be sure as I don't have the extra $ to go replacing them if they blow!
;D  BK  ;D
Title: Re: Welding h3-45 info
Post by: kemo3ce on January 29, 2015, 10:04:33 PM
Ok I'm new to this so bear with me, can you guys tell me where these things are or where they are located so I can disconnect them?
Title: Re: Welding h3-45 info
Post by: Jon on January 30, 2015, 03:04:28 AM
I think (remember that, I am not sure) you have to disconnect the ECM at the RH lower side of the block, 2 connectors. Then in the steer bay there are one or two more transmission or engine ECMs that need to be disconnected.

I would remove the ground in the rear which likely has a stack of cables going to it.

You don't say if the coach is homebuilt, seated or professionally built, but if needed I would also disconnect the grounds on the house battery system, which should disconnect the equalizer if one is used on the house. Ditto with inverters.

If I remember correctly you can find instructions for disconnecting on the Prevost web side. Go to the commercial side, maintenance and then to the appropriate page, which might be the shop manual on the publications page or maybe on the webinar page.
Title: Re: Welding h3-45 info
Post by: Boomer on January 30, 2015, 07:15:18 AM
The maintenance manual gives directions on what to do prior to welding.  If it's converted, turn OFF the inverters BEFORE shutting down the house batteries. I don't disconnect the house bats but I do remove the chassis bat cables, and of course the ECM and trans
harnesses.