# Cat 248 Skid... Aux Hydro isn't working



## Mick76

Just seeing what you guys might think the problem is... my 248 Skids Aux Hydros arn't working... I push the buttons and neither are working... switch or relay? something else?
I checked the fuses already and these are the standard hydros.....

TIA
Mike


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## Maxamillion67

Mick76, I have 2002 242 Caterpillar skid steer, and my Auxiliary Hydraulic do not work. I got a hold of a Cat mechanic on-line at just answer and this is what he told me to do. I have not had time to check this out on my machine because I do not have a heated shop, so I am waiting until it warms up to check it out. I also got a schematic from him, if you PM me you email address I will email it to you. I hope this helps you out. 
Don

You have accepted an Answer!
From Donnie Fri, Jan 15, 2010 12:28 AM EST
Good wiring will have less than 5 ohms resistance. Use the wire number from the solenoids and disconnect the wires from the ecm. Check all four individually. Check the handle switch as well. You may have the wrong part and it should plug into another wire group. 

Here is a simplified schematic, it should be close. The full one is to big to send.



View Full Image 




Here is some basic testing to check the ecm. 

CHECK THE OUTPUT OF THE ECM


Remove the floor plate in order to get to the ECM.

Locate the wires P978-GN and L998-OR coming out of the ECM.

Enable the machine.

Push down on the A1 switch.

Measure the voltage from wire P978-GN to wire L998-OR. Measure the voltage on the back side of a connector or by penetrating the wire insulation.
Note: Two people will be needed to perform the measurements. One person will need to occupy the seat in order to keep the machine enabled. The other person will take the measurement.

Expected Result:

The voltage should be greater than 10 VDC.

Results: 


OK - The voltage is greater than 10 VDC.
Repair: The problem does not appear to be electrical.

Stop.


NOT OK - The voltage is less than 10 VDC.
Repair: The ECM is very unlikely to have failed. Reconnect all connections and visually inspect the wire harness. Verify that the values that are present on the machine configuration screen match the machine's options. Verify that the values that are present on the machine configuration screen are installed correctly. Verify that the diagnostic code still exists. If the diagnostic code still exists perform the test steps again.Replace the ECM, if the cause of the diagnostic code was not found after the second attempt. See Testing and Adjusting, "Electronic Control Module (ECM) - Replace".

Stop.

Test Step 5. CHECK THE SWITCH CIRCUIT


Remove the floor plate in order to get to the ECM.

Remove the wire harness from the ECM.

Press the switch (A1).

Measure the resistance from contact 52 to contact 53 of the wire harness connector.

Press the switch (A2).

Measure the resistance from contact 52 to contact 62 of the wire harness connector.
Expected Result:

The resistances should be less than 5 Ohms on both of the readings.

Results: 


OK - The resistances were less than 5 Ohms.
Repair: The ECM is very unlikely to have failed. Reconnect all connections and visually inspect the wire harness. Verify that the values that are present on the machine configuration screen match the machine's options. Verify that the values that are present on the machine configuration screen are installed correctly. Verify that the diagnostic code still exists. If the diagnostic code still exists perform the test steps again.Replace the ECM, if the cause of the diagnostic code was not found after the second attempt. See Testing and Adjusting, "Electronic Control Module (ECM) - Replace".

Stop.


NOT OK - The resistances were greater than 5 Ohms.
Repair: The circuit is open in the wire harness and/or the connector. Repair the wire harness and/or the connector or replace the wire harness and/or the connector.

Stop.

If you still don't find the problem, let me know and post your findings. We will get into more detail then.



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Thanks for using Just Answer, please remember to "accept" my answer if it is helpful. Feedback is greatly appreciated.


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## Mick76

Max,

I can't pm you. You don't have enough posts yet.... but If you could email the schematics that would be very helpful... my email is [email protected]

Thanks!


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## Maxamillion67

Mick76, email has been sent, good luck with it.


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## NICHOLS LANDSCA

Ok I didn't read the whole thing but simple things to check. Does the backup beeper work? If the fuse is blown they won't work. The reason I know is I have pulled the fuse for the beeper when working late and they won't work. Also there is a breaker switch/button in the engine compartment, mine are on the left side toward the front. Just push it to reset.


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## Mick76

Nichols, yes the back up beeper is working.... I'm thinking its either the switch or the solenoid..... anyone know where the solenoid of the aux hydrolics is located?


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## NICHOLS LANDSCA

Did you try the reset button?


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## Mick76

The reset button is a 60 amp... what does it control being a 60 amp? Id imagine its for the entire machine? I cant tell if the button is engaged or not but doesn't do much when I push it.... just as a side note, it seems like everything (with the exception of my float option) is working fine on the machine, its only the aux hydros that I'm having a problem with


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## jwilsonf

*cat 257 aux not working also*

I am curious about this also i am haveing the same problem with a 257 got an answer on just answer but it says need to hook up to scanner to see what is causing this. I dont have access to that. the aux power switch has no power ive checked the fuses and relays and everything seem good but cant get no power to switch any suggestions??


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## Mick76

I had to take mine to my mechanic. Mine came down to either the joystick to a tune of $300 or the computer $500.... I choose to splice in a toggle switch instead of buying the $300 joystick which I believe is the problem. works just fine now.


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## jwilsonf

*switch*

does your joystick switch still work or you just run toggle on all of it? did yours not have power at the switch on the cab? mine doesnt have power there.. thats whats got me bumfuzzled. if it had power there i would think it was the joystick or ecm but no power im kinda clueless..


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## Mick76

Just the toggle works the aux hydrolics now. Mine didn't have power to the joystick or the toggle up by your left ear... cat states it could have been the joystick or the computer.....Whats your email address?.... I'll send you the electrical schematic (cat wants to charge $150 for the damn thing!)


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## jwilsonf

*Switch*

[email protected], friend has a 287 that done the same thing they replaced ecm on his, fixed it. i was hoping maybe the solenoid switch or something simple, do you still use the joysick buttons at all now? thanks for your time


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## Mick76

no joystick buttons now, just the toggle... email coming


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