I was working on a pile of dirt and without warning or sign the boom lift stopped working and I was stuck with a load of dirt in it. All else works fine.......... I removed the access panel and lifted the seat up after checking hyd fluid........ Aux right hand control stick and Curl pedal are both moving in and out freely and work fine when machine is on and off. I think someone has improperly rigged / rewired the machine hydraulic controls to some extent, because shouldn't they lock when machine is off, and when seat belt is disconnected and seat is empty?.......... Boom lift (up & down) pedal is locked but all hardware / pedal appears fine........... All three plugs to the 3 solenoid do not have power at their plugs. Switched around the plugs, still no help or change. I don't have power on all 3 solenoid plugs. Seems like power interruption is before (as in closer to the battery) the 3 power wires separate to go to their respective solenoid plugs. Where does power for the solenoids come from? What places should I look to find interrupted / broken power? Or can a safety mechanism cause this?............. I can't see the wire loom past 18" back (boom is stuck down so I can't remove side panels for better visual) and no diagrams I've found tell me either. I assume they may go to a different place than the Aux power wire goes, since they are separate wire looms? Or is it same place? Again, there is no power on all 3 of the solenoid plugs, even though the Curl and Aux solenoids seem to be working all the time, and never lock the pedal/stick, even with the loader off and key removed, seat belt off, and seat empty. I switched them around and nothing changed or improved. Made no difference so I put them back. So all 3 power wires to all 3 solenoids do not have power, yet only the vertical boom movement does not work. What is going on?........... I connected a 12v jump start box to each solenoid to attempt to get them to actuate and nothing happened either. No sounds or anything. So I have no power to these 3 solenoid plugs, and no operation even if I apply power to the solenoid from a test battery............ All cab/motor compartment fuses seem to be good but I don't think any fuses relate to the hydraulic boom anyway. I checked 2 of 3 the engine compartment relays and swapped the two identical ones and nothing changed either. The third relay is twice the size of the other two and seem to be starter/ignition related because a heavy gauge red wire is connected to it, and a few others. Can the larger relay be responsible?............. What and where could be interrupting the power to those solenoid plugs? Doesn't seem to be fuses or relays, unless it's the large one. Where does the power come from for the 3 solenoids? And what could interfere with the solenoids working when I supplied power from an external power source?........... Would removing and inspecting the solenoids make a difference? I did not want to further disturb the solenoids until I get experienced inputs. I have pictures of all areas if anyone wants to see them. Thanks!
NH LT185B track loader strange safety & hyd solenoid malfunctions
- Thread starter ylekyote
- Start date
The power to the interlock solenoids comes from the instrument panel. The power originates from the 5A fuse in the engine compartment fuse panel. It is the second from the bottom of the block closest to the engine. Don't confuse the aux switch with the solenoids on the lift and bucket spools of the valve. The aux switch is just an on off switch and does not lock anything. If the axu switch was bad the engine would not start..........You need to remove the solenoid from the bucket spool and see if the pin is stuck in the up position. Without power the pin should stick down past the face of the solenoid. Remove the lift solenoid and using your power pack supply both ground and power to the two terminals of the solenoid wire pigtail. If the soleinoid does not pull the pin back in then the solenoid is bad..........Be sure the service/run switch in front of the cab fuse block is in the run position.........To check if you have power to the solenoids, you need to be in the seat with the seat belt fastened and the key on and the service/run switch in the run position.........The interlock sequence is the following. Before sitting in the seat have the key in the off position. Upon sitting in the seat watch the instrument panel. The panel should light up and go through a self test. Once the self test is done there sould be two red lights flashing yet, the seat belt and the park light. Fasten the seat belt and the seat belt light should go out leaving the park light flashing. The engine can now be started and the hydraulic solenoids should release the foot pedals.
Thank you Mike. Missed this earlier today somehow but caught it after posting and then reinspection. This rig has possibly been rolled over or otherwise damaged so some wires have been added as work around. The safety circuit that connects the seat/seat belt sensors to the loader operation has been rigged. There was a short in the new wiring they routed under the seat and a mini 7.5 amp inline fuse had blown. The short blew the mini fuse. I replaced it with another that was larger amp to test, and then it blew the 5 amp battery fuse in motor bay. That's when I noticed it was shorting out against the seat bottom frame Only guess is the original safety circuit got messed up in rollover or whatever (mice even) so they made a new safety lockout circuit to meet safety standards for OSHA or dealer resale. The first owner was a concrete maker. They traded it at a dealer and I bought it from them after they had it for about 6 months. I can't believe I bought this loader and didn't catch more of these problems.... Hydraulic leak(s), rigged wiring, weird lockout or lack of lockouts. Lesson learned. She's a bulldog though when she runs! Lol. Can't complain about performance at all.
While checking cab roof fuses I noticed I do not have a "service/on" toggle switch as the operator manual says should be present on page 3-22. There is a cavity for it, and 2 or 3 screw fastener holes, but no wear/rub signs otherwise it was ever there. Is this an optional switch? I see wires above it in roof panel but nothing seems to be spliced or modified. There is a soft rubberized plug that has 3 wires leading to its backside, and a rubber plug/cap that seems to be made for it on the front. Maybe this is a plug for the "service/on" switch plug when so optionally equipped? Maybe in an accident or wiring problem the previous owner disconnected and removed this switch. Looks like the plug's protective cap is professionally mass-produced for the 3-wire plug though...it's not terminated and wrapped cheaply, like I would expect from a owner's DIY removal.
If your instrument panel is made out of metal then there should be a serice/run switch. If the instrument panel is plastic with the light switches in the insturment panel, then there is no service/run switch.
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