Problem With My Battery Cut Off Switch

[Mspike]

I'm a proud new owner of M936A2 wrecker that has an electrical issue. The battery cutoff switch doesn't always cut off the battery. Sometimes you can start it in the off position. I'm assuming this is a faulty switch, but before I go after it I wanted to see if anyone has had a similar experience. If so is there a better cure/fix than just replacing it. Anyone have any success with refurbishing it one? Thanks in advance.

 

[M35A2-AZ]

Is the cutoff switch on the neg. cable? Also the shave port shorts to the cab sometime and will give you some odd things. Put the shave port cables on the battery side of the switch and that will fit that problem.

 

[Mspike]

Is the cutoff switch on the neg. cable? Also the shave port shorts to the cab sometime and will give you some odd things. Put the shave port cables on the battery side of the switch and that will fit that problem.

I should have been a little more clear that what I was referring to is the battery switch on the dash and not a separate battery disconnect.

 

[M35A2-AZ]

I should have been a little more clear that what I was referring to is the battery switch on the dash and not a separate battery disconnect.

Ok, Sorry, You may want to put a battery cutoff on it anyway.

 

[Guyfang]

I could be wrong here. But I seem to remember that the battery switch on the dash turns on and off, a circuit breaker. The circuit breaker cuts off the battery power to your controls, and you can not start the truck. Could very well be the switch. Or, what you might have is a stuck shut sometimes, circuit breaker. It may sometimes open when the switch is turned to off, and maybe sometimes not. You need to test the switch first.

This sounds stupid, but when you move the switch back and forth, whats it "feel" like? Smooth, even, strange sounds? Sometimes you can feel it not working. You can test the switch with a MM, (multimeter) by taking off the wires, setting up the MM for ohms and measuring the switch terminals for continuity, (on) and for no continuity, (off). If the switch reads continuity when the switch is off, or you get a partial reading, chances are the switch is bad. Test it 10-20 times, since you said it only happens sometimes.