My 1981 D3B has been running great till a few days ago...had used the machine for 4 consecutive days then of the fifth day...no start...nothing...not even a discernable "click" anywhere. Checked battery (less than a year old) and battery connects...all checked good. Also checked for power to and from start switch and it was good. An electrical wiring starting diagram would be very helpful!!
I had something of the sort happen to my D3C it was the battery kill switch wore out I guess anyways the way to tell is take your booster cables and take you neg and connect it to your termenial then connect the other neg and connect it to a good ground and give it a spin amd see what happens it took me half a day to figure this one out.
check your starter out, make sure you have constant power and the remote wire is working, every caterpillar starter i have ever had go bad has done exactly like this, I just put one on one of my d4's about 3 weeks ago
I know you said you have power,did you load test the battery? They can show voltage with no amps.
Battery load tested good. Can't find a "battery kill switch" mentioned in post #2...don't believe there is one on the machine. There is a small electrical device on top of the starter near the solenoid...could this be what is sometimes referred to as a "sender"? Is this a relay of sorts?
I think he is referring to a Master switch; it is nothing more than a battery disconnect switch. Keeps your machine from burning up while you are gone. Have you tapped on the starter and the solenoid with a small hammer? Sometimes on these older machines the solenoid will hang up and no power will flow through it. Since you said there is power at the key switch, this is not likely to be the problem, but it won't hurt to try. Just don't get carried away with the hammer.
This happened to us on a Cat excavator. Turned out to be a circuit breaker just off the positive battery cable feeding the machine its power. As previously mentioned, check power at battery and go down the line with a test light. Good Luck, VC
D3B Wiring I had to make 2 copies to get the diagram.
Thank you hthunder !! Now that I know where to look and what to look for surely I can run the problem down.
There is no battery disconnect switch....even though there should be. There is a transmission safety switch that ought to be checked.
There is a small electrical device on top of the starter near the solenoid...could this be what is sometimes referred to as a "sender"? Is this a relay of sorts?[/QUOTE] This is called a magnetic switch, it is a relay.It controls the starter switch in the solenoid.When you turn key on dash switch this switch should pass power to small wire on starter switch. Good luck Bob