I have a Hitachi ex120-2, serial 12n-38558, and for clarity the graphics say kx120. Currently the hydraulics do one of two things. I'm not sure which wire goes to which solenoid at the top of the pump since neither are marked, both fit, and the solenoid is the same. In one configuration, the pump runs at FULL POWER. The engine is running full power, the exhaust is smoking. If I switch those two wires, the hydraulics run EXTREMELY slow. It doesn't matter what mode in the cab, they are running at a crawl, barely moving, but everything sounds fine. Engine is running normal, no crazy exhaust. The pump was just replaced, so the solenoids on the pump would appear to be "new" since they come with the pump. Anything else that comes with the pump, such as sensors are also new then. We purchased a new wiring harness to rule that out, but what we received, doesn't seem to be exactly what is on there. The one end connects to everything at the pump side, but the other end doesn't seem long enough to reach wherever its supposed to go (we can't visualize that) and it seems to combine into another wiring harness that goes up to the engine compartment...so who knows if its the correct harness. The harness was from Friday Parts Hydraulic Pump Wiring Harness 3094204 for Hitachi Excavator EX100-2 EX120-2 EX120-3. Thank you for any help.
Looks like the factory machine wire harness wire color for pump displacement Solenoid valve #1 terminal 2 is OrL and the machine wire harness wire color for pump displacement Solenoid valve #2 terminal 2 is BL . Pump displacement solenoid valve #2 is closest to the engine. . I have never heard of a separate hydraulic pump wiring harness for that series of machine. The wiring harness part # 3094204 is good at Deere just have no indication of where it is used.
Can you please confirm what those "colors" mean? Also in the manual we have it suggests 2-2 is Y and 1-2 is RL. I don't know what those mean. I can tell you one plug has a yellow wire with thin black line and a red wire with a thin blue line. The other one has a yellow wire with thin black line and a solid yellow wire. Also, I had started to replace the wiring harness when I realized that part 3094202 didn't actually go anywhere on the other end, so I put everything back and now I created a new problem. Not sure why, the plugs are all unique, so I couldn't have plugged anything in wrong. The EC motor arm is constantly running as soon as I put power to the machine and the power mode selector is now always in "P" mode and pressing the selection buttons do nothing. These all worked prior to me trying to change the wire harness.
I am pretty sure that -2's and -3's have different machine wiring harnesses. Pump Solenoid #1: This solenoid increases pump displacement when energized. On all 490Es, EX120-2/3, 790E up to s/n 24999 and EX220-2, this solenoid is located on top of the pump closest to the engine. On 790E s/n 15000 and EX220-3, this solenoid is mounted on the end of the pump and is the lower one. Pump Solenoid #2: This solenoid decreases pump displacement when energized. On all 490Es, EX120-2/3, 790E up to s/n 24999 and EX220-2, this solenoid is located on top of the pump farthest from the engine. On 790E s/n 15000 and EX220-3, this solenoid is mounted on the end of the pump and is the upper one.
So this matches the colors of the wires on my machine. And I can now confirm that the wire that is mostly red with a blue line is connected to solenoid 2 which is furthest from the motor. The wire that has solid yellow and yellow black is connected to solenoid 1 which is closest to the motor. In this configuration the machine runs with extremely slow hydraulics. Also, I still have the "new" issue after putting everything back that the "EC" motor is constantly cycling its arm when power is turned on to it. And that the mode selector switch is only in P mode and won't switch to anything else. I can also add that the engine doesn't stop when the key is turned off now. All of these things unfortunately are new now that I put the original wire harness back. None of the plugs can be swapped so I don't know what is going on with that. And now the engine is revving a bit when running. Before it was nice and smooth, but it just stayed in very very low idle...probably part of the extremely low hydraulics.
So my post #2 was pure crap :-( ……sorry about that @easternmarine . Thank you @mg2361 for straightening everything out, Gotta love a good Deere manual.
No woi No worries, any thoughts about the underlying issues?
I think you where on the right track replacing wiring loom. Most likely chafed and corroded and now open or short to engine actuator. Is the correct part available?
I thought I had the correct part. If not, the correct part is a huge harness. Seems like it runs everywhere outside the machine.
From the symptoms and the way they changed from the original post, I would say there is an issue with that wiring. Check your messages for some restroom reading material
First, I took my excavator for repair to Scotty at Elliott & Frantz in King of Prussia, PA. They were able to fix all the issues and I wanted to share that information here for future reference. This post was about the hydraulic pump wiring harness and then about throttle control issues. The throttle control issue was apparently a "simple" fix. My understanding was that two wires in the pump access area were simply plugged into the wrong things. I was under the impression all of the connectors in that area were unique and that wasn't the case. So this was the "fix" to the fact that the engine control motor was running non stop and that the throttle controls would select anything from the ILEP menu. Once corrected, he simply did the engine learning which consists of key on, press P, wait 10 seconds, key off. The hydraulic issues were a bit more difficult. First there were two sensors that had "been replaced" with parts from FridayParts, but as people have noticed, those parts are questionable. They replaced the DP sensor $1800 and the angle sensor $900. This made a difference. In addition, they discovered a spring clip was missing at one of those sensors which would convince the machine to run slow hydraulics all the time. After correcting those items, they hydraulics all work normally. So at this point the machine appears to be operating normally. Unfortunately with parts and labor it came to a $7500 bill. I am pretty irritated about that, so beware if you use this company. I was told I would be pre-charged $2000 for diagnostic labor. I would then receive a call to approve any additional charges. Well I received a call, but only after they did another $5500 in labor and parts. So i was pretty pissed about that. I'm not sure what I would have done, but to do nearly 3x the price in repairs and labor and say, whoops...didn't settle well with me.
Did anyone ever come up with a good part number for a pump harness!? I got the same one you did, and the harness in the machine is way longer and has more connections than the one I purchased. Mines in pretty rough shape, thinking of splicing the aftermarket on in just to see if it solves my problem. Pretty much identical symptoms to you
We never found one, but we simply replaced the connectors where we found failures.
The Pacific Hillbilly on YouTube is rebuilding his Ex120-2 back to factory specs. He has a spreadsheet showing all the prices and part numbers for everything he’s rebuilding. He paid $1044 for a complete OE harness. Maybe he’ll reply if you shoot him a message.
“Pump wire harness” is part # 3094204 .