Hello Im trying to help get my sons machine running again. it was diagnosed by a mechanic that just said the Hydraulic Lock solenoids are not engaging. There are 2 of them The parts are $800 so I need to figure out how best to test the solenoids. I see there are 2 and I doubt that both went bad at the same time. the solenoids 2 of them have 2 wires coming out of them. Is one wire ground and the other power and does it mater which one polarity wise that I can energize to check function? or test with multimeter for open circuit or short or do they ground at the base sorry I am trying to learn bout these machines its a 2015
Doesn't help much. Need a Serial Number.
Sorry here it is 2015 Cat 302.7 D mini excavator. Serial number LJ700604
I'll send you an electrical schematic.
Thank you, Nige I will post back when I get it running
Hello Everyone, so I found a bad relay called K58 second speed relay but after replacing it then I tried starting it the starter now does not crank. there is 12.8v power getting to the large lug on the starter but I can’t get my hands or eyes back there to jump the starter solenoid. can i apply power somewhere else in the harness? looking at the diagram there is something called a starting relay somewhere, where I don’t know that seems to have a wire marked 10 that goes to the starter solenoid. does anyone know where to find that starting relay marked K7 on the wiring diagram? or can I pull off the small wire from the starter solenoid or is I bolted on? I didn’t want to tug on it and break it. here is the plug I’m looking at to apply power or check the relay if I can find it
Behind the cab under a cover by the looks of it. I take it you don't have an Operaiton & Maintenance Manual.? They are really useful and at around $50 they are not expensive.
Thanks for sending that. I think my son has it, I will look for it when I can go to the machine. but the motor did start, there is apparently an issue with the switch on the left joystick armrest. Someone removed the safety switch from its location and it has to be manually manipulated to allow the engine to start. Im not an operator but I think this switch also controls the hydraulics since that is the existing original problem. I think it’s called the safety switch and it looks like it has 4 wires And it’s located in the joystick arm you lift up to get into the seat I assume 2 wires are to lock out the ignition and the other 2 lock out. The hydraulics Does anyone know which 2 wire I can jump to bypass this switch to test it? For hydraulic function?
So it's #20 in the illustration below, correct.? If so it is shown by Part Number and wiring connections in Grid G-8 on Page 2 of the electrical schematic. If the existing switch has failed in some way why not just replace it.? I
Thanks for the diagrams they really helped. I found the safety switch number 20 had been removed from its mount but I tested and it works as it should. Engine fired up now. Back to the original problem, no hydraulic at all. found a bad solenoid called fast speed valve solenoid by the pump. Had to order that one. found a bad relay, replaced that one and found hydraulic level below sight glass. After the solenoid arrives will post back any results.
So, what did you find out? I'm having same issue. Tested my safety switch on arm rest, has power out of blue and brown when disengaged, but black and black white don't seem to be doing anything. My blade solinoid melted. Waiting for parts, switch and solinoid. Just curious why people say there gonna post results and never do. Forums are helpful
Try this thread. A bit long winded because nobody except the OP was there with the machine. Got there eventually though. If you want an electrical schematic please post a Serial Number to identify the correct one. One snippet you may find interesting that the dozer blade lock solenoid power is on the same circuit as the safety switch in the armrest. HeavyEquipmentForums
Nige, an electrical schematic would be super helpful! Thank you for responding and any help that you can give! Serial number is: LJL01150 2013 CAT 302.7D
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Yes, check the blade lift solenoid. This to my knowledge is the 2nd one this year to have turn out to be the blade lift solenoid. Maybe yours too.
Also check fuse in the number 4 position to make sure it's not blown. It's the horn and hydraulics fuse. I would also run and ohms test on that solenoid to make sure it was good before I did anything else.
Thank you for this. I recently lost all hydraulic control and here's what happened. The blade solinoid fried and it took out the arm rest switch. Symptoms started when I kept blowing to horn/aux fuse. I put a 30 amp fuse in because I couldn't find the problem, it fried the solinoid and that caused the main switch on the arm rest to fry. I replaced both and have hydraulic power again. Here's the issue though. Cat wanted $1000 for the entire blade solinoid. It says it's a 24volt on the description. I pulled mine off and it said 12 volt. So I took the part number and found a dozen solinoids on eBay, put it on and works great. $50!!! Why would cat say it's 24volt when the part number is 12? See pictures of solinoid and switch.
The description is incorrect. It's probably generic text lifted from a stock library. That solenoid will most likely operate on anything from 10-32v DC, that's how they are usually rated.
Well that explains it thank you very much for your help with this!
Was looking at some LED lights for a customer of mine and they were rated from 10 VoltsDC to 30 volts DC. Same thinking. Simon C