Disconnect Switch on New Truck

Step up to a Cole Hersee #75908 switch. Higher amperage rating, silver contacts and 1/2" studs. Having a battery disconnect switch is one of the best moves you can make.

We at the County had a shop burn down a few years back from a unit with this issue, so we put disconnect switches on everything after that. Now all the Cat ,John Deer and new plow trucks come with them from the factory. Actually the Cat and John Deer equipment have come with them for years. Far as I am concerned everything should have them.

It is also much quicker to do welding repairs when you have them. Turn it off do your repairs and then turn it back on and your out on the road again, with no chances of hurting the newer electrical systems.

I don’t think it really matters which side you disconnect. You could say that with the disconnect near the starter you could still have one of the long positive cables short to the frame somehow and still cause a fire even with the disconnect open. If you open the ground side there’s nothing for a bad positive cable to short to and a bad ground cable can’t short to the frame anyway since it’s normally connected already .

Guess I’ve never had a fire, I usually install a disconnect to keep a small drain from killing the batteries over a period of days or weeks sitting. I like to put the disconnect near the battery box under drivers door, but that doesn’t always work out if there’s a second box on the passenger side. I’ve got a 4WD tractor that I would like to put one on just because I think it’s a good idea, but it has multiple grounds that I think will require a couple disconnects. So far it’s not causing any problems so I haven’t done it.

Here ya go Mike. Paccar factory disconnect switches. My older 2002 had a pair of them mounted through the floor left of the driver seat. Pull up and twist to disconnect...
Flaming River brand from factory outside of battery box. Have them in all of the trucks but never use them!
Had one KW go into shop and mechanics said we had electrical issue with the T-800; NO POWER...
Last mechanic worked on it and parked it, with powered OFF position, as he didn’t know how soon we would pickup the unit. And I wonder why we pay a shop over $165.00 an hour to “repair” trucks? They had 3 “technicians “ scratching their heads with the diagnostic tool plugged to the port...unreal.

Juice, technician today have no trouble shooting skills.

Another Mercer driver had his Paccar truck catch fire going down the road so I put mine by the seat. Only cost $105. Switch 65 cables 40. Already had the 49/64 drill bit.

hey mike,

ground side switching has a smaller arc when contacts are broken with current running through the circuit. a lot of manufacturers have used it over the years. its a head scratcher when you haven't worked on one before. I worked on a kenworth that was late 90's early 2000's about 15 years ago, the owner had installed rotating beacons for wide loads and they only would work for about 5 minutes before it starte popping the circuit breakers, and they would come on when you stepped on the brakes etc, turned out, that entire truck was wired with ground side switching, and the owner had installed the light circuit with positive side switching, he had used a common ground so his circuit was powering up others and vice versa, had caused lots of weird symptoms.

Deere/hitachi excavators also used ground side switching which caused funny symptoms when the switch failed closed or the wiring harness rubbed through causing a short to ground.

night switches are great, and i have only seen them in the ground side of a machine for the reasons mentioned below, take the ground side off and nothing can short to ground and cause arcing/fires.

Thanks guys. Got the 200amp switch. Much better with 1/2 studs. Only cost $65. Why does Cat always put the switch on the ground cable and not positive?