Help. New member here. Bought a used Bobcat 843B on CL a few months ago. Ran good when I bought it. Parked it and have started it up every few weeks to keep everything in good working order. About a week ago all I would get is a clicking when trying to start. Charged and tested the battery. Tried to jump the starter solenoid and it would not engage the starter. Replaced the starter solenoid and it fired right up after installing the new solenoid. After a few minutes of running it ran really rough. Would run fine at low idle but really rough when you put the coals to her (throttle up). Sounds like a fuel supply issue and I am replacing the fuel filter as we speak to see if that solves the problem. However, running rough is not my main problem right now. I can't even get it to start now. When I was fiddling around with the throttle issue the ignition switch was acting up. Sometimes it would turn the machine on, sometimes not. Almost like a loose wire or loose fuse. Work called so I had to leave it for a few days. I tried to start it yesterday and when I first turned the key on - guages worked, good voltage, lights, everything worked and it cranked up fine. I turned it off and tried to start it again. This time nothing - no guages, no lights, nothing. I know there is power getting to the starter because I can jump the starter solenoid and it tries to start the motor. Works fine when everything is cold. When the machine warms up, the ignition switch does not work. Both fuses are good. Is this a starter relay issue, or an ignition switch issue, or something entirely different? Anyone know how to troubleshoot either? I do have a manual for the machine from the previous owner and a wiring diagram, but the electrical troubleshooting chapter is not very helpful at all. I'm admittedly not very keen on electrical issues.
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OldMachinist
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Sounds like dirty/corroded connections but could be a bad battery. Have the battery tested, clean both ends of the battery cables and make sure there's clean metal at the ground connections. Next would be to find and clean the rest of the ground connections like the one to the ROPS(drivers cab).
Hello RW... I think on your 843B the terminations on the back of your ignition switch are held with screws. You might check those. I might suggest you trace the accessory wire which I believe starts out from your starter terminal (8 gauge red wire or so with fuse link) and works it's way up to the cab through some rubber molded plugs right above the fuel tank at base of cab attachment points then up into your console / control panel. As OldMach stated .. possible corrosion issue, could be a bad / corroded ignition switch, these have failed in the past with the machines sitting out in the weather. Best of luck to you! JLM
Forgot, one more thing.. A good DVM or Digital Volt/Ohm meter or a simple 12V test light can be your best friend when troubleshooting this kind of stuff.
JLMWith a manual and a DVM should should be able to make some headway. With my 843 I found the bulbs for both warning lights burned out, but I never really knew it. They should come on when you turn on the key. I also had saw dust inside the gauges that caused some weird problems. I'd suggest you remove the seat and tracks and clean out all the crap you will find under the seat and then prime and paint the area. Its a collection spot for wet dirt and sawdust. In addition to various things that got dropped like rags, screwdrivers, beer bottle, etc. Also if your hour meter does not work, its probably not the hour meter but a hydraulic oil pressure switch.Forgot, one more thing.. A good DVM or Digital Volt/Ohm meter or a simple 12V test light can be your best friend when troubleshooting this kind of stuff.
Thanks all for the advice. Will tip the cab tonight and clean everything out. I did check the ignition switch with my DVM. I don't get complete continuity between poles for both start and glow plugs. 1 being no continuity at all, 0 being complete continuity, I was getting readings of between .4 and .3 With the ignition switch should I be getting good (complete) continuity between the poles? I also took out the two relays behind the coolant reservoir. According to the wiring diagram, one is for the pre-heat (glow plugs) and the other is for the starter. Both were rusted and gunked up pretty bad. One of the large lugs on the starter relay is not completely secure. When I loosen the nut to get the wiring off, the lug itself turns inside the relay housing. Does this indicate I need a new relay? How much do they run?
HanSolo
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- Sep 11, 2012
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I'm with OldMachinists on the battery. Try swopping with a known good battery. My M700 had a six months old battery that wouldn't hold a charge after running the machine for several hours. Took it back for exchange and the auto parts store tested it and said the battery was fine. They blamed the alternator, starter, etc (all of which have been rebuilt). But when I started the Bobcat with another known good battery, no problem. I always try and have a spare 600 CA battery handy.
If you are going to measure ohms on the ignition switch your safest way to get a valid measurement is to disconnect the switch and do the measurements. Otherwise you may measure through some component you did not expect. And the battery should be disconnected. If your ohms measurement was to actually connect the starter circuit you would be in trouble. I doubt if the contact area of the relay is actually rusted. There should not be any steel in an electrical circuit. Do you get +12 at the relay when the switch is held in the appropriate position. That relay is just going to power the glow plugs or starter solenoid. Things get a little tricky measuring voltage when a large load is introduced. If you had a bad battery or bad battery connections the relay could energize the starter solenoid but when the load of the starter comes into play it can drop the voltage so low that the relay or starter solenoid will kick out.
