302.7d solenoid problem

[ThadSchug]

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.

 

[Nige]

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'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.

 

[ThadSchug]

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?

 

[Nige]

The blade solenoid is on the far end of the bottom side of the main control valve.

 

[ThadSchug]

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.

 

[ThadSchug]

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.

 

[Nige]

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.

 

[ThadSchug]

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.

 

[Nige]

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.

 

[guzzi27012]

Sorry, I just read this, I'll try tomorrow to read mine.

 

[ThadSchug]

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!!!

 

[SteinarN]

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.

 

[Nige]

Sorry, I just read this, I'll try tomorrow to read mine.

We are still looking for that resistance info for another machine with problems. Can you measure the one on your machine please.

 

[007]

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

 

[Nige]

I understand your point but I would imagine that very few people have the wherewithal to do that.

 

[Nige]

If the solenoid have a resistance of 210 ohm and voltage of say 26V

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.

 

[guzzi27012]

I will try to get the info tomorrow

 

[Nige]

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.

 

[guzzi27012]

 

[guzzi27012]

Between 7.1-7.6 for blade lift solenoid
Number 9 was 7.5