I am new to the forum. I have a 1997 Cat 311B 8HR----- excavator. I had it sitting this past winter and everything was working properly when I put it up last season. Now the auto idle function does not work for me. It shows that it is on on my screen and after I first start it up if I turn it on it will occasionally idle down after a few seconds but will not work again after it calls for power. I can manually idle it down with the dial and it will idle down when I press the idle down button on top of the right joy stick. I have checked for broken wires but I cant see any. I did take out the speed control sensor and it had some stuff on it so I cleaned it and re-installed it. Still nothing. I did notice that the deceleration cable for the governor actuator is becoming frayed and a couple of strands are broken underneath the dust cover right before it hooks to the engine. Any information or tricks that any of you may have would be greatly appreciated. This is a homeowner machine I am using on my own property in preparation of building a house. Everything else seems to be working normally and there is no lack of power when operating it. I just want it all working.
Has anyone had this problem before or just me?
You need to post your SN so the gurus here know how to start thinking it out with you.
the serial number is 8HR00792. Thanks Gary!
That's a grey market machine and there isn't any parts information on in SIS and, unfortunately I can't find another machine which shares commonality with it. BUT. The problem is likely to be a faulty pressure switch. There is one switch to monitor if implements are commanded and another for the tracking. It's unlikely that both are faulty, but not impossible. Will it idle up if you work the tracks? You will need to find the switches on the machine. They will be on the main control valve somewhere. Luckily there is a good wiring schematic for the machine. You should be able to find the correct switches from the wiring colour. You're looking for A771 purple and L971 Green. When you find them, unplug them one at a time and with the machine in the idled-down state, bridge the terminals in the harness connector and see if it idles up. If you do find a faulty switch, the part number is right there on the schematic - 1060179, which updates to 3095795.
If you do replace that cable there is a calibration process (common to all machines that use that actuator) which needs to be followed. Also I would suggest to only use a genuine OEM cable. According to SEPD1884 the 8HR-prefix ISJ machine crosses to the "export model" 8GR-prefix. I would guess the electrical schematic for an 8GR machine should work, but am prepared to be proved wrong. One thing you really need because of the lack of information in the online system is a Parts Manual. If you get a copy of XEBP7664 that ought to work. The original Japanese Parts Manual XJBP7634 can be ordered from your local Cat dealer and maybe will work better. The Part Numbers in the Japanese manuals are in "English" and the illustrations will be the same. It's only the part descriptions that are in Japanese.
Electrical Schematic SENR9236-01 covers both 8GR & 8HR excavators, plus a whole load more models besides. Another thing. You should have the "Black Box" for the pump control in the back of the cab. What warning lights are showing on it when the machine is running.?
Thank you Sir. I have part manual XEBP7664 so I will utilize that as much as I can. I’ll try and get into it sometime this weekend and see what I can find. I truly appreciate the insight.
I'll send you a copy of the electrical schematic. Keep an eye on your messages.
Forgive my ignorance but can you clarify what you mean when you say “bridge the terminals”? I can do basic wiring but I like to make sure I know what I’m doing so I don’t short something out.
Join the two terminal in the harness plug together using a piece of wire, bridging the coloured wire to the black wire. (200 Black is always ground in Cat world) Well done for asking if you're not sure.
Thank you. It’s expensive enough to fix when things go wrong. I don’t like to be the cause of extra problems all because I think I know what I’m doing. I have learned from experience unfortunately.