Hi, I had an engine speed sensor fault. I couldn't get a Kobelco sensor in time so I bought a sensor from another excavator (CAT) which was readily available. I attached the connector from the old sensor unto the new one so that I can connect it to the harness. I started the engine and now I can see a speed indication ~680rpm (should be 1000), however when I turn the Accel dial, the engine is not accelerating. If I disconnect the speed sensor, the the engine speed increases with the Accel Dial. I reconnected the speed sensor and again i have no control with the Accel dial. Is this an issue with the Mechatro or maybe the sensor I installed cannot work with the Kobelco? Any thoughts? Thanks guys
Good day Can you tell us which of the engines you have Yanmar or Mitsubushi, is the speed sensor mounted at the flywheel? Kind regards Uffex
It’s the Isuzu 4G1BT engine. Yes, the speed sensor is mounted at the flywheel. Thanks
Good day When you install the sensor, be sure the teeth are across the centre of the port. Wind in the sensor until it meets the tooth and then back it off one and half turns. Measure the voltage at idle it should be 3 volts +. Kind regards Uffex
Hi Uffex I double checked the installation of the sensor, I screwed it in till it touched the tooth then backed it off 1 1/2 turns. At idle, I’m getting 6.7 VAC at the sensor and the same at the plug for the ECU. However I’m not seeing an rpm reading on the display. I have another issue, I’m not sure if it’s related. The engine does not switch off with the key. When I turn the key off, the governor lever only slightly moves backwards which isn’t enough to shutdown the engine. There is a lot of space between the pump lever and the stopper bolt. I had to temporarily shorten the linkage so that I can get the engine to stop. Is it possible that the ECU is not driving the stepper motor sufficiently to stop the engine? Or faulty stepper motor?
Good day It apperas that you have more going on than just the speed sensor, Im not sure if you can see any errors that may give us some clues. Kind regards Uffex
Hi Uffex Thanks for the quick responses. The display wasn’t working for years so the owner kept working the machine as is. I finally got the display to work, so now I’m fixing all the errors that are showing up. 1) Air filter clogged sensor bad- It has broken off, I can’t find a replacement, so I disconnected wires and this error cleared. 2) Speed sensor error, I used one that I could find in the local market. I had to cut the plug off the old one and attach to the new one to plug into the harness. I ordered a Kobelco one, it’s on its way. 3) PSV C propo valve error- solenoid is bad. I ordered one, it’s on its way. 4) key switch does not stop the engine- key is a bit loose on the switch. A new key switch is on its way. But I think there is an issue with either the governor or the computer which is not driving the lever to stop the engine. When I clear all the error codes with the solenoid installation, I’ll try the A adjustment to see if this is resolved. 5)key switch fuse blows every time the key goes to the ON position. That fuse is bridged for now until I can figure out the issue. There are 5 diodes to the back of the computer, they are all good. There is one inside the battery solenoid that’s bad. Can this cause this problem? These are all the issues I have for now, lol. I have a big job coming up so trying to get this going ASAP. Thanks for all the assistance
Good day I suggest we see what happens with the correct speed sensor.Pulling each of the output cables from the switch should help to find the bad one. Kind regards Uffex
Thanks a lot Uffex. I'll provide an update as the parts are switched out. Another question. The E STOP cable is sticking and I want to replace it. How involved is it to replace? Do I have to scrap half of the machine or can it be accessed by removing the radiator and fuel tank?
Good day Hands up never changed one out, if its so difficult I would suggest convert to an electric stop. Kind regards Uffex
Thanks Uffex, electrical stop solenoid ordered
sounds like you have a short in your harness somewhere from your key switch possibly back to the alternator. the alternator is how the controller tells if the engine is running. pull the key switch plug and ohm each wire against ground to find your short then trace the bad wire till you find a bad spot. if your engine harness is the type that I'm thinking of it runs behind the intake manifold and over the water pump Wich if where they usually fail. there should also be a set of diodes one by the alternator and one by the starter solenoid check to make sure they aren't shorted.
Thanks for the response Kyle, I’ll take a look at the wiring harness from the switch. Actually I’m seeing a few extra wires connected from the switch, apparently an electrician did some tinkering for the last owner. I was trying not interfere with this at the moment in the essence of time, but it looks like I’ll have to bite the bullet.
Hi guys, So I fixed some of the issues listed above. New speed sensor was installed, I had to adjust it a little closer to the flywheel from original spec for it to read properly. PSV-C propo valve error. I still have this issue after installing a new solenoid. I checked continuity on the wires and for short circuit, the tests passed. I’m getting 24v on the terminals at the solenoid. I swapped plugs from a solenoid close by that have the same specs, but the error remained with this PSV- C output. I even replaced the old solenoid to another location, and it tested good. So it points to an issue of a bad output from the ECM. Where can I send my ECM to repair this output? I’m from the Caribbean, so somewhere in the US would be more convenient. Thanks
sorry I can't help with that one. the only place I knew of was in Texas but they aren't in business anymore