I am thinking of putting a master switch (battery disconnect) on my 90xt for safety and security reasons. I'm thinking it doesn't matter which cable I connect the switch to, positive or negative, or am I out to lunch? thanks
Doesn't really matter at all in that case, as it will open the circuit either way you do it, same as removing the terminal from the battery, and nothing will get power.
General practice is the negative cable although either will work One advantage of doing the ground side is the switch terminals and new wires pose no risk of shorting out to ground
Our skid has it on the negative cable and is located behind the rear door. I have a couple people besides myself that have keys to the equipment and it gives me a piece of mind during break downs. Everyone knows not to turn switch on without calling first.
I always use the ground cable. Waaaay safer. If you hook it into the positive, the lugs on the back will be hot all the time. Drop a wrench on it by accident, if one of the lugs gets bent and touches the body or if the switch fails and shorts internally you may as well write off the machine because its probably gonna burn.
Ok thanks guys, ground cable it is !!! Thanks again
Never thought about that..... that would be a bummer indeed..
just something to think about.... killing all battery power, while it may be an easy theft deterrent, may cause some "issues" with on board electronics. not familiar with your specific machine, but ive seen in the past on other brands, fault codes get generated when repeatedly disconnecting the battery. an alternative to the battery disconnect would be wiring a hidden toggle switch in the starter wire. switch on, the machine starts, switch off, the machine powers up, but will not crank. thinking like a thief ( or unauthorized user) if the machine powers up, but wont start, i'd be thinking theres something wrong with it, but if it doesnt even power up, i'm gonna start looking for a disconnect switch...
Crewchief88 I tried to get the mechanic shop to give me a wiring schematic for my tractor a few years ago so I could do the same thing you are talking about. Figured I could just put a switch in one of the blanks by the work lights and only I would know. They argued that the only way to do this was with a master disconnect switch like a dozer. I told them I was worried about constantly losing power to the computers like you say. I finally found a shop manual a few months and still plan on doing it if I ever find the time.
If you're worried about causing damage or losing radio setting etc you need to wire a fuse across the master switch terminals. That way all the systems keep power but if someone tries to start it with the switch turned off, the current draw from the starter motor blows the fuse.
Every single machine in the fleet where I work has a master disconnect switch (as per lockout policy). They get switched off all the time and we've never had a single issue. The newer tier 4 stuff with DEF we were told to wait 5 minutes before switching it off. Apparently the DEF system needs some time to purge or something.
The DEF machines I've seen have a light that stays on while the fluid is being purged from the piping back to the reservoir. Turning off the master switch before the light goes out will set a code in the computers. I've never experienced any machine that would have computer problems disconnecting the battery for any amount of time.
maybe i should clarify my meaning... ive never seen disconnecting a battery cause a "problem" that the operator will ever see or notice, but it does set a code, the only person that may see it would be a dealership mechanic that has factory software capabilities. it's annoying having to see 40 codes related to the battery being disconnected every time the machine is parked. it's one of those things that makes you start wondering *** is going on, when the customer is complaining about electrical problems...
I've never seen a Cat have a code for the battery disconnect being shut off. I've never seen a code on a Deere/Hitachi or a Komatsu have a code when the battery was disconnected. There are places here, mostly in the woods, where you have to install a disconnect before you will be allowed into the forest.
The DEF will also stay froze in cold weather if not purged back to the heating system on shutdown and cause headaches on startup.