Looking for some diagnostic help with a SK160LC throttle control. Not sure of the series but buddy said late late 90's. The throttle motor seems to be hunting for the proper spot, meaning it is moving back and forth slightly on it's own and does not move when commanded to by dial. Is there a brain box between the throttle dial and throttle motor? Or does the dial act direct to the motor? faulty dial, throttle motor or wiring. Any advice help or past experience much appreciated.
It sounds like the stepping motor is looking for the limit switch. Yes it is controlled by the main controller. You didn't mention any codes on the dash? To diagnose the problem you should do continuity test at the stepping motor, wire harness, and controller. You wont like hearing this but I suggest calling a dealer. wes
I second that. That stepping motor and the control of it by the Mectrocontroller is not a simple process, and even if you decided to take a guess and figure the stepping motor is failing, first of all it's expensive, and second, it's not exactly plug and play to install a new one, there's a procedure one must follow to install a new one or it may go up in smoke.
Thanks for the reply and insight. I asked buddy if there was any codes on the dash and he said there was not. I have worked on Daewoo/Doosan and smaller Case excavators (Kobelco) but not the mid-size Kobelco. Sure seems like the motor is not reaching the limit switch and is therefore hunting for it. I would think that the stepping motor would be the most vulnerable piece of the puzzle, some DVOM work should verify that. As for not plug n play I didn't think it was that complex of a system to not be plug n play? Can you give a quick run down of the procedure? Thanks again for the help.
Most of these systems, when you turn them on they go through a check run where the motor goes to full high then low idle to calibrate both ends of the scale. When installing a new motor there's a manual calibration procedure to introduce the new motor to the computer and get them to shake hands Willie?
I suppose that's about the best way to describe it. :drinkup In the past I've got information from a number of techs that have way more experience with these things than I, and from what I gather the stepping motor itself is not all that complex, but the connection to the main controller is. For example, I've been told to never grab the lever on the stepping motor and manually move it back and forth with the wiring harness connected to the stepping motor or you can potentially flip out or even damage the main controller. I can't say that will be the result, but I dang sure will heed that warning and not find out the hard way. The procedure I got from an experienced Kobelco tech goes something like this: Install stepping motor with throttle control rod not connected to stepping motor control arm, wiring harness disconnected, split in arm lined up with index mark on shaft (that's your starting point). Index S/M slightly into engine run position. Connect continuity tester to wires to internal limit switch as shown below. Index arm slowly to stop position until you get continuity on test meter. Move lever slowly toward run position until no continuity. Connect harness. Have helper turn on ignition. S/M should move back, then dance a moment, then move to start position. Turn key off, S/M should go to stop position to kill engine, then move up slightly to start position, then display goes off. Re-locate arm on S/M shaft if necessary to connect control rod (disconnect harness connector if you have to re-locate arm). Reconnect control rod, start engine, have helper slowly turn throttle control knob to full throttle. Very important, make sure control lever on injection pump does not contact hi stop bolt on injection pump. With throttle control knob at full tilt, you should have throttle control lever either just shy, or just touching the hi stop on injection pump. What you do not want is that lever against the stop and the operator still has clicks left on the throttle control knob. Throttle down, turn off ignition, make sure engine quits and display goes off.
Nuttin' to it if ya knows how to do it! :drinkup
Thanks again guys for the reply, wow manual calibration fun fun. Buddy has had the motor off twice and reinstalled I wonder how out of whack he got it?
If it's not to late don't remove the splined arm from the shaft, if it's been in the right spot for the last few years it's still in the right spot. How bout the shaft itself, is it loose in the housing? Ball joints not seized up, to loose? If you do have a good limit switch by willie's test, And your not getting "S/M" fail code on your cluster gage (assuming your cluster gage is good** something else is wrong. For more detailed info we need to know what machine this is. Count the # of buttons on the cluster gage If there is 8 total you have a minor change machine, 1 button, pre minor. Serial #'s are good too.
We had this problem on the Mark 3 model SK120's and a few times it turned out some burnt out transistors that actually drive the stepper motor that are inside the computer (underneath seat)