Ordered part number 3860880 $744 non returnable/no warranty from CAT solenoid and before I put it on, I’m looking for some advice. What causes a solenoid to fail? I don’t want to put it on and it fail in 20 minutes because there is really another underlying problem. “Replacement pressure relief solenoid for main control valve assembly that directs main pump oil for main functions of Cat machine” is the description…all I know is that my hydraulics quit working. It seems to go to the the blade controls and the fast/slow driving speed. Cat 302.7d. Any advice, appreciated.
Hi The common cause of solenoid break down is that the winding circuit has a break, not so common maybe vibration & heat contribute. You can check out the windings easily with a multimeter I guess according to your photo's it is a little late for that. Kind regards Uffex
Well, you definitely NOW have a bad solenoid. As suggested above, most solenoid failures are electrical, in that the windings either break or melt together. I'm a little slow here, so, maybe you could tell me why you focused on this part initially? If ALL hydraulics quit, I'd think open pilot solenoid or broken pump coupling. I'm a little rusty on Cat minis, but, IIRC, the blade is typically run off a gear pump and everything else is from the main pump(s).
15/01/24. Hello Catjoy. I got exactly the same problem. Did you get it resolved?
There is a lot of reasons the coil will fail and it is usually heat which causes the coil to swell and expand and often breaks the coil wire some where internally causing an open circuit or short. If the slightest spec of debris gets caught between the internal plunger and the S/S sleeve can cause the internal plug not to travel all the way up inside the coil magnetic field when energized. This causes excess current to be drawn by the coil and over heats it. Since it sounds that you have purchased the complete solenoid that resolves that possibility. Under voltage when energized can cause a week magnetic field and cause the same problem. Checking the new unit with a multi meter should resolve any issues like that.
As he hasn't been on the site for over a year, and never responded to questions from others who were trying to help (see above) my suggestion would be to start again from scratch. Describe the problem you have on your machine and any information that might be relevant regarding how it started. Throw in a Serial Number as well and I'm sure someone will try to help you.
Looks like i have the same exact problem does anyone know if there is a compatible part or after market part?
Are you SURE that solenoid is your problem or do you just THINK it is your problem based on symptoms.? What machine do you have.? S/No.? What symptoms do you have.? As mentioned above by @007 neither of the other two posters enquiring about this have ever been back since their first visit, so your diagnosis is going to have to be done from scratch.
its a cat 302.7d cr am having problems with the same solenoid listed on the pictures above am testing it with direct current and doesnt seems to open..i lost power on some hydraulic cylinders looks like thats the main solenoid for the line gp control from there goes straight to swing drive..my swing power aint working eather
OK, here's the deal. There are different models of 302.7D and different characteristics within those models depending on Serial Number. That's why it's needed. With the S/N at least there is halof a chance of looking up technical information. Have you lost ALL hydraulic functions or just some.? If it is only some then please give a list of what functions are affected. Have you tested the resistance of the solenoid coil.? How many ohms did you measure.?
The solenoid its reading 6 ohms and i lost power on the swing and the bucket cylinder as well
Do you have hydraulic functions on everything else.? From memory that would be travel, dozer blade, boom, and stick functions.
thats right everything else is working
To me 6 ohms of resistance on a solenoid coil of that type seems awfully low. I would have expected it to be in the 70-100 hom range. Problem is I can't find a specification to tell me what it should be.
Well i installed the new part and didnt fix the problem know i dont have current on plugs it might have a short somewhere will keep you posted
If you would like to post a Serial Number you're welcome to an electrical schematic to help you trace power.
I think I have a similar problem to this but not 100% sure. My 302.7D keeps blowing fuse #4, which goes to the horn and the hydraulic solenoid. I actually took it in for service at a dealership 3 yrs ago for the same symptoms. They replaced the entire wire harness and charged me almost 6K. Now the same symptoms, fuse #4 popping when engaging any hydraulics. Fuse #4 is labeled horn and hydraulic solenoid, Horn has never worked or been used. Any suggestions on where I should start trying to diagnose? I can't aford another 6K trip to the shop for a non fix. Thanks!!!!
Start with a Serial Number please. That gets you an electrical schematic. You'll need a multimeter for some of the diagnosis.
Thanks for asking, the Serial Number is Cat 3027DHLJ700271. Symptoms are, machine start, but then hydraulics are enguadged the #4 10 am fuse (horn and hydraulic solenoid) blows. Sometimess hydraulics work for a min or 2 , then the fuse blows. I'm not sure where the solenoid is to even check to look it over. Thanks, much appreciated.
Check your message inbox. electrical schematic on the way, That circuit seems to feed two solenoids, 386-0559 for the implement lockout (mounted on the hydraulic pump) and 386-0880 (munted on the main control valve) for the dozer blade. I would suggest maybe unplug the solenoid for the blade and see whether or not the fuse continues to blow.
Thank you so much, this is extremely helpful, I appreciate it!!! I will try the solenoid to the blade, and if that doesn't work the other (if I can find it). I would like to disable the horn to see if that is an issue. Do you have any suggestions as to where the connection to the horn is so I can test that? I believe the button is on the right joystick, but it hasn't worked for years and it's not labeled. I think the actual button popped off.
I'm sorry I don't. Although the horn assembly is shown on an illustration, its location on the machine is not. However on a machine as small as yours it shouldn't be too hard to find. It's going to be somewhere under the front of the machine, tucked behind a panel either on the LH or RH side.
Hello- I'm back at it after about 6 months of distractions. After reading through some other threads that you (Nige) were involved with, I'm leaning towards the blade solenoid. The problem is I don't know where to find it to test it out? I assume that by unplugging the wire to the blade solenoid I could see if fuse #4 still blows?? I removed the metal foot plate in the cab, but not sure how to identify the blade solenoid? Can anyone help?
The blade solenoid is on the far end of the bottom side of the main control valve.
Slow down , you're dealing with an amateur here. So, that would be the back side of the maching kind of near where the fuel tank is? I'll take the panel off that and see if I can find it. Might need to confirm with a pic.
That's it--the blade solenoid is bad. The fuse doesn't blow when it is disconnected. It must be a fault in this Cat model because there are 3 posts on the forums that mention it. Any suggestions on where I could get a new part? I'm sure the Cat dealership in Raleigh, NC will charge an arm and a leg for it. I'd rather get it anywhere but there.
Ask at the dealer for Part Number 386-0880. That will be the complete solenoid valve, the coil is not available separately. Try measuring the resistance of the coil and post the results.
Great, thanks, so much. 210 ohms from the fuse in in slot 4 of the box with the safety handle down. Not sure what number is normal.
Neither am I because I can't see a specification for it. Hopefully someone who has a 302.7D can measure theirs and supply that info.
Sorry, I just read this, I'll try tomorrow to read mine.
Update: I ordered the complete solenoid from Cat (386-0880, $900) because, as Nige mentioned, the coil comes attached to the solenoid and I could not find separate parts identical to the originals. I had to unhook 4 hydraulic lines to get to the part, plus a lot of twisting, pushing, and pulling to get the solenoid over the blade adjuster mechanism... Nevertheless, I finally got it off and the new part went back on easy. So far the machine is working like it should. I now get a resistance of 100-120 ohms from the top of the 10 amp #4 fuse. It was 210 before the fix. I think the root of the problem may have been poorly aligned or a loose connection on the blade adjustor anchoring bar/nut that is regulated by the solenoid. I made sure that was straight, tight, and properly adjusted before hooking everything back up. Many thanks and much appreciation to Nige and others on the forum for your help!!!
If the solenoid have a resistance of 210 ohm and voltage of say 26V then the wattage is only 3,2W which is not much at all. 110 ohm gives a wattage of 6,1W which is still not much but twice the 210 ohm wattage. Solenoids in many other applications often are around 10-15W, for example refrigeration systems etc.
We are still looking for that resistance info for another machine with problems. Can you measure the one on your machine please.
Hi Nige, Alot of multimeters can not measure resistance properly when it comes to these little coils with alot of fine turns in them. The induction is very high and you get ridiculous readings. One way which is messy but gives a much better reading is to connect the coil to a known voltage and use your meter to measure the current flow. Using ohms law calculate the resistance of the coil. (R=V/I) The plug or some iron should be in the coil. Cheers
I understand your point but I would imagine that very few people have the wherewithal to do that.
If I understand it correctly the resistance of the complete circuit (quite a complex one TBH) that is fed from the particular fuse was measured at around 210 ohms, not the particular solenoid we are looking at. Also it is a nominal 12V circuit. I would expect a solenoid coil for this type of application to have a resistance of less than 20 ohms, maybe even less than 10.
I will try to get the info tomorrow
Thank you in advance. If you can unplug the electrical connector of the blade lock solenoid and just measure the resistance of the coil that would be perfect. While you're at it.......... Can you measure the resistance of the coil on the implement safety solenoid as well.? That's the one mounted on the implement pump, #9 in the illustration below.
Between 7.1-7.6 for blade lift solenoid Number 9 was 7.5
Thank you sir. Seeing as your solenoid is pretty much new IMO what you measured should be a representative number to use for testing purposes.
Your welcome. You helped me out so I returned the favor. Yes the solenoid maybe has 4 hours on it
Bonjour, Je suis francais aux antilles et je possède une pelleteuse Caterpillar 302.7 qui a un problème presque similaire a ce post. Mr Nige ma déja bien aider avec le faisceau électrique, mais après recherche je n'ai pas de problèmes du coté électricité. Mon électrovanne de sécuritée fonctionne bien mais je n'ai toujours pas d'huile qui circule aux distributeurs. peut etre il n'y a plus d'entrainement des pompes mais cela parait étrange car j'ai éteint la machine puis lors du nouveau démarrage il n'y a plus de commandes qui fonctionnent aucun bruit ni fumer n'est apparu. doit t'il y avoir de la pression a la pompe secondaire quand la machine est en marche? En vous remerciant pour votre aide.
Almost 100 percent the blade lift solenoid. Mine had the exact same problem. In the thread there are ohms reading from a brand new one in this thread. Take those readings and check it against the one on your machine.
Merci pour votre retour, je vais contrôler la résistence de la bobine et le cablage. Merci
Nous parlons bien de celle ci?
Yes that one.
Also check fuse number 4 ( the horn and hydraulic system) this typically breaks when that solenoid goes out
C'est fait tout ce qui est électrique est bon mais je n'ai pas contrôler cette électrovanne.
par hasard auriez vous le schema hydraulique? car je ne comprend pas pourquoi cette électrovanne ferait que les commandes hydraulique du bras ne fonctionnerai pas!
No I do not have the schematic. I can tell you from experience that I’m almost sure that is your problem. I had the same problem last year. In this forum there is a 5-6 page thread between myself and Nige about this while issue. If you want to search for it it was in August of last year. It was a whole thing. And after all the trouble shooting it turned out to be that.
Hello! Is fuse #4 blowing when you engage any of the hydraulics? It has a picture of horn and some squiggly lines. So any hydraulics work after starting?
Merci pour l'explication, lundi je contrôle cette électrovanne. et a force de chercher j'ai trouvé le schema hydraulique, mais il manque la nomenclature. ce n'est pas grave pour comprendre le schema.
Bonjour, tout ce qui est électrique fonctionne bien je n'ai pas de problème de fusible, j'ai tout tester sauf la bobine qui est sur le bloc distributeur que je vais contrôler lundi. quand je démarre je n'ai rien du tout en commande et aucune sortie d'huile a la pompe hydraulique.
voici le schéma de fonctionnement des joysticks qui sont alimentés par l'électrovanne de sécurité. c'est juste pour aider d'autres membres a comprendre le fonctionnement
A bad solenoid valve will blow fuse and all hydraulics will not work. I replaced with original cat part because it’s not easy to find same shaped component and it needs to fit in a tight space.
bonjour, Finalement c'est l'entrainement de la pompe qui a lâché et sans faire le moindre bruit , juste en démarrant! c'est quand même fou!
When the hydraulic oil is "cold" there is a fair amount of resistance to rotation within the pump. So a failure during the first engine engine start of the day would not be unusual.