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950g cat loader warning light stays on

Lewis12

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I got that clogged hydro filter light that stays on the display. Changed the filter and the sending unit but it still comes back on? Anyone know of anything else that can set this warning light off? If I remove the wire of the sending unit on the filter housing it doesn't come on. So that tells me that can't have a short. The wire is grounded also when the warning light comes on.
 

Nige

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That's a pressure switch. If the light goes off when you disconnect the wire then the logical conclusion is that the switch is defective. The light comes on when the 499 Grey wire sees ground through the switch body. Suggest you replace the switch. Part Number is 7X-8549.

upload_2019-2-16_17-44-38.png
 

Lewis12

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Yes that is the correct part number but I had the whole filter assembly replaced with a new switch on it. Besides a restricted filter I don’t get what could make the switch go off. Could any restriction in the hydro tank cause this? The machine doesn’t get hot just the warning light and the indicator for hydro filter goes off. The switch is grounded by the filter body assembly when the pressure rises at the filter.
 

Lewis12

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Using the same oil we used all the time 15-40 oil. The filter was the correct one from caterpillar. The problem just popped up recently never had the issue before. The pressure switch was replaced first then had bought the correct filter from cat but they ended up sending the whole filter assembly with the pressure switch again. So this would be the second new pressure switch and same issue. With the wire on switch disconnected warning light stays off just don't get what's making it come on with it connected?
 

kshansen

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As Nige says need more information, but on a completely different Cat loader back in I believe 2009/2010 I had a problem that appeared to be a plugged transmission filter switch intermittently acting up but after living with the problem for months found the problem to be a temperature sender going bad.

Do I understand on this machine you can get the warning light to come on by grounding the #499 Grey wire but if the grey wire is removed the warning light always goes out?

Also just to be sure did you post the serial number of the 950G?
 

Lewis12

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Yes if I manually ground the grey wire to the frame warning light and indicator pic comes on like it's supposed to. If I remove the wire they go away all day. Once I put the wire back on the sending unit after some time the warning light comes back on. When My transmission indicator flashes i do replace my transmission filter and the light goes away for that. Only Serve code on monitor is engine oil temp sensor erratic but that's been on with no warning light buzzing.
 

Nige

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I am still not clear on how this is behaving, and your mention of the transmission filter is only muddying the waters. Let's concentrate on the hydraulic filter warning.

First - machine serial number please.........
1. With the machine running and the hydraulic oil at normal operating temperature, if you have the wire not connected to the plugged filter pressure switch and you connect it, does the plugged filter light come on immediately..?
2. If you have the wire connected to the plugged filter pressure switch and you install a new filter element, from first start-up is always on with the machine running..?
 

Lewis12

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Don’t have serial # right now but the parts book being used is for AXX1-UP will post seriel # soon.
When I had the new cat filter and new filter assembly with the new pressure switch the hydraulic warning light didn’t come on right away with the pressure switch wired up. After like 3 hrs the warning light beeped and the indicator flashed. When I took off the wire to make it stop beeping and put it back on the pressure switch the warning light didn’t come back on right away. The warning light just comes and goes randomly. This filter seems to be installed on the return side of the hydraulic oil so I can’t make of what’s making the switch ground out randomly even with a new filter installed. This machine has one oil line from the filter going to the tank and the other oil line comes from the hydraulic oil cooler with a one way check valve installed at the cooler and goes to the filter where it has a tee there for another small oil line. But this oil travels from the cooler through the one way check valve goes through the hydraulic oil filter and then goes through the other oil line at the filter back to the hydraulic oil tank.
 

kshansen

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Sorry about muddying things with mention of transmission filter. My bad!

Agree 100% on cutting open and inspecting old filters!

If nothing else seems to help explain the problem would it be possible to Tee in a 30 psi pressure gauge to the port the sender is mounted in? Spec's for the 7X-8549 switch call for 16-20 psi to activate and it should deactivate at 12.5-15 psi. At least you would then be able to have a "second opinion" that the pressure is the problem and not a wire rubbed through and going to ground somewhere giving a false indication of plugged filter.
 

Lewis12

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I did cut open one of the filters but didn’t see anything. Took a sample anyway just to send it in.
 

kshansen

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One more idea off top of my head. Would it be possible if the breather on the hydraulic tank was plugged for it to cause enough pressure in the tank to actuate the sensor? As it only needs to see 16 psi to turn on the warning light it might be possible. The tank is already under some pressure but not sure what the spec's are for those relief valves in the breathers.

Most of the ones I ever dealt with were mounted on the side of the tank so dirt would just fall away. This one appears on top of the tank and could get dirt build up around it. I always made it a point to remove disassemble them and wash out the brass filters several times a season.
 

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Lewis12

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I will clean out the breather and look into installing pressure gauge. Also could it be also possible that the screen inside the tank might be plugged causing this issue? I see in the parts book there is like to screens inside the tank.
 

Lewis12

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Where is the warning horn located so I can unplug it and see if the light comes off and on while operating. Also that file is the same loader because the breather is on top.
 

kshansen

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Where is the warning horn located so I can unplug it and see if the light comes off and on while operating. Also that file is the same loader because the breather is on top.

Best as I can tell from looking in parts breakdown and wiring schematics is it should be in the cab in the right rear corner as you are sitting in the seat. I know that is were the ones were located on some of the bigger machines I worked on. Might have to remove some panels to access it. It looks like this drawing from parts book:
warning alarm.png
Not sure I would run machine too much with it unhooked because if there is something else going wrong you won't know it! This same warning alarm sounds for all serious problems.
 

Nige

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A couple of comments: -

1. Without a Serial Number it's impossible for those of us who have online info to be sure we're looking at the same thing you are.
2. If you don't know the S/N how can you be sure the Parts Manual you have is the correct one for your machine..? Just sayin'. As a comment there are no less than 15 different Parts Manuals for 950G of different Serial Number prefixes.
3. I'm with KSH. You can disconnect the warning horn for a short test but remember it's the warning horn for everything related to the machine Monitor System.
4. If you have sent off an oil sample for analysis post the results when you get them.
5. If you went to the expense of buying a complete new filter head then I would personally buy a new breaker relief valve for the top of the hydraulic tank and have done with it. On loaders we used to replace those valves on a 2000hr PM. They suffer a lot more than you would imagine.
 
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kshansen

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A couple of comments: -

2. If you don't know the S/N how can you be sure the Parts Manual you have is the correct one for your machine..? Just sayin'. As a comment there are no less than 15 different Parts Manuals for 950G of different Serial Number prefixes.
Not to belabor this point but with all the running changes Cat and others make on a machine the serial numbers is about the most important piece of information when looking for help and information, I as well as Nige try to push this point not just for you but the next guy who needs help.

To go off on a tangent, which I tend to do too often. Just the other day on a walk-behind snow blower form a guy was asking how to change a belt on a ST824 machine(no, not a Cat). Well I looked up that number and found that the manufacture uses the same "sales" model for at least two very different machines! One had one belt to drive auger and the wheels and another that had separate belts for the auger and the drive wheels. Just imagine how upset this guy would be if I or someone else went into details on the project but it was for the wrong version on the machine!

5. If you went to the expense of buying a complete new filter head then I would personally buy a new breaker relief valve for the top of the hydraulic tank and have done with it. On loaders we used to replace those valves on a 2000hr PM. They suffer a lot more than you would imagine.
This also is an excellent idea, especially if like many machines the people taking care of them don't know the part even exists so it has been covered with six inches of dried mud for years!

Also at times even Cat does not have engineers who have a good understanding of the conditions these machines work under. More than once I found it important to relocate a breather to get it to a place one could actually reach and not get buried in dirt and dust in the matter of a couple weeks,
 
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