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303.5 Dead hydraulics.

O

osullt

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Apologies for posting on another forum already.

Any help would be appreciated. I have a 303.5 with less than 2000 hours on it. It has never had any issues in the past. It has not been used seriously in 10 years but it has been moved around the garden and used to do maybe 20 minutes of scraping at a time every few months.

It was moved into a new position in November. Last week I went to move it and she started first go as usual but none of the hydraulics are working.

The drop down safety switch seems to be working as the ignition will not work with it down.

I suspect it is some sensor or electrical issue, fuses are all ok. I do not have a repair manual or electrical layout.

Machine is stuck in my back yard locking in a car that I want to use.

Can anyone suggest where I might start looking for an issue.

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osullt

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Just looking at the schematic,
I am thinking the hydraulic disable relay is first point to check,? this area seems to have gotten wet as the drain at the door catch has rusted through and water is dripping into that part of the cab.

If not the relay then the hydro disable solenoid...?
 
Nige

Nige

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Having thought a little more about it I think your best bet is to follow the power on the schematic.

1. Find the solenoid on the schematic and work backwards right to the particular fuse in the fuse box that supplies power to the relay. Start there on the machine and work forwards to the relay.

2. At the same time look at where the circuit that pulls in the relay coil is powered from and trace that to the relay.

3. If both of those check out when you energise the lockout then you need to look further downstream towards the implement lockout solenoid.
 
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osullt

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Nige said:
Having thought a little more about it I think your best bet is to follow the power on the schematic.

1. Find the solenoid on the schematic and work backwards right to the particular fuse in the fuse box that supplies power to the relay. Start there on the machine and work forwards to the relay.

2. At the same time look at where the circuit that pulls in the relay coil is powered from and trace that to the relay.

3. If both of those check out when you energise the lockout then you need to look further downstream towards the implement lockout solenoid.
Click to expand...
Thanks for that. All fuses are ok. The disable relay clicks when the lockout switch is activated. Also No joy when I jump that relay.

Freezing and raining here (Ireland) now so abandoned until tomorrow. Hopefully I will have access to multimeter and some test leads at that stage, and I will check supplies to the solenoids and continuity of any wires that seem relevant.

Many thanks for the help we had a great CAT dealer here when I bought this machine but they closed,

No signs of rodents in the digger since it was two weeks old, at that time a rat ate the entire manual which was in the box under the seat. I never even got to read it...

We have a cat and have poison stations around the place because we kept chickens until recently.
 
Nige

Nige

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osullt said:
All fuses are ok. The disable relay clicks when the lockout switch is activated. Also No joy when I jump that relay.
Click to expand...
How did you test the fuses.? Really need to put a multimeter or test light connected to machine frame ground on both sides of each fuse to confirm that you have power in and power out.

The fact that the relay clicks only indicates the coil side of it is apparently working. If there is no power coming into the supply side of the relay then nothing will be going out to the solenoid. The power to the supply side of the hydraulic lockout relay relay comes from the "solenoids" fuse via wire 131-A56 BR only when the key is ON.

1704730406646.png
 
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osullt

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I took a more simplistic route, I read the schematic to say that the relay when engerised connected the brown to the green wire, which took power to the hydraulic disable solenoid via M927.

A test light shows good power at the brown with machine running (even with the armrest up! Suggesting something else is wrong) for me the next is to get the cover off and check properly for power and earth on hydro disable solenoid. (Few hours with daylight and absence of rain will help)

If that is not shot, and I can't find something obvious, I'll be stumped again.

Many thanks for taking the time on this.


Screenshot_20240108-162337.png
 
Nige

Nige

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Note that in your snip above the hydro disable and speed select solenoids are shown as being the same 144-5986 Part Number.

If you confirm power/ground at the 2-pin connector F-C13 on the disable solenoid try swapping the 2-speed solenoid in its place, even just swap the connector if the one from the 2-speed will reach. If everything works normally then you have your answer - and the Part Number of the replacement solenoid that you require to boot - bonus...!!
 
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osullt

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That's very interesting...certainly will give that a try...thanks again. I think the disable will also act on the flow through the 2 speed solenoid, so swapping connectors won't tell me anything, but they are easy to access with the covers off.....
 
Cmark

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Another thing to consider. Disconnect the delivery hose from the pilot pump (3). If you have zero flow with engine running, you probably have a failed pump drive coupling.

1704742564728.png
 
Nige

Nige

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osullt said:
I think the disable will also act on the flow through the 2 speed solenoid, so swapping connectors won't tell me anything
Click to expand...
It will tell you something if you prove that there is power/ground at F-C13 but the installed disable solenoid does not click, then if you disconnect the machine side of the F-C13 connector and temporarily connect it to the 2-speed solenoid and you can hear it click........
 
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osullt

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Apologies...was in Spain for a few days R&R...will update when I get a chance to go back at it...very grateful for the pointers and will definitely update thread with progress or lack thereof...
 
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