Cat 226b thumb wheel switch replacement

[Nige]

Thinking about my post #99 above and trying to explain it better.
It's not the measured output voltage on the "roller signal" connection from the switch that determines the actions of the ECM. Whatever is the voltage with the switch in the centre position becomes the "reference voltage", and it doesn't really matter what that voltage is but the ECM notes it.
From that point the change of output voltage resulting from the thumbwheel switch being rolled backwards or forwards is what triggers the ECM into action to do whatever action it's programmed to do based on the change of input voltage from the reference value.
So getting hung up the value of the output voltage from the switch can become somewhat of a distraction.

 

[JAY-MV]

I have same issue with same switch on telehandler. (it has 2) Swapped magnets and worked for a couple hours and failed again. After sitting works fine. Can it fail internally after warming up? Is there an otto replacement. Was looking at buying one to try but not sure why it didnt work

 

[pbd05]

Otto won't sell the cat specific ones when I tried. My issue ended up being some broken wires coupled with a "swollen" magnet.

 

[Nige]

The Cat thumbwheel switch requires a dedicated 8v DC supply. Otto do not sell a switch of the specification, at least not commercially, although I have long suspected that they manufacture the switches for Cat.

 

[Billj324]

I dont know if this helps, but I’m working on a 308E2 that has a problem with this roller switch. I finally decided to take a crack at it again today.
Problem: has thumb attachment, rolling forward, opens the claw, rolling down, nothing happens. No change in engine speed, no pressure in the hydraulic tubes. Went from working to non-working same day, after lunch break, no changes to the machine, no apparent codes.

Testing: measured signal on both left and right stick rollers. Center is 4v, full forward is 1.9V, full down 6.23V. Left roller functions up and down.
My thoughts: will the hz function on my dmm serve me better here than the voltage setting? According to specs, output is 500hz plus/minus 80. Thats 460-540hz range. The dmm displays the RMS, so the voltage being read may not be proportional to the duty cycle. Speaking proportionally, 8*.2= 1.6v, meaning Im off by .3v, same with the other side.

I took another magnet and ran it and played with it, but could not get it to respond in the “down” direction. The switch was surprisingly clean too.
Beyond a possible open connection, or faulty ECU, what else am I not considering?

 

[Billj324]

I dont know if this helps, but I’m working on a 308E2 that has a problem with this roller switch. I finally decided to take a crack at it again today.
Problem: has thumb attachment, rolling forward, opens the claw, rolling down, nothing happens. No change in engine speed, no pressure in the hydraulic tubes. Went from working to non-working same day, after lunch break, no changes to the machine, no apparent codes.

Testing: measured signal on both left and right stick rollers. Center is 4v, full forward is 1.9V, full down 6.23V. Left roller functions up and down.
My thoughts: will the hz function on my dmm serve me better here than the voltage setting? According to specs, output is 500hz plus/minus 80. Thats 460-540hz range. The dmm displays the RMS, so the voltage being read may not be proportional to the duty cycle. Speaking proportionally, 8*.2= 1.6v, meaning Im off by .3v, same with the other side.

I took another magnet and ran it and played with it, but could not get it to respond in the “down” direction. The switch was surprisingly clean too.
Beyond a possible open connection, or faulty ECU, what else am I not considering?

Crap. I think I posted that all wrong/wrong place

 

[quiksilvr]

Crap. I think I posted that all wrong/wrong place

i think you'll be ok with posting it here for now.... as for the thumbwheel switch, have u tried removing the switch from the joystick and opening it up to have a visual of the magnet inside?

 

[quiksilvr]

the reason i ask is that its possible only half of the magnet is intact.... if u can open up the switch and verify, that would help

 

[Billj324]

i think you'll be ok with posting it here for now.... as for the thumbwheel switch, have u tried removing the switch from the joystick and opening it up to have a visual of the magnet inside?

 

[Billj324]

I did. Was very clean, wires going to are great shape, no rust on the springs. Tried to get it to function by placing the rollers magnet on back-side of the sensor with no reaction, to that or a bigger magnet I could find. Tried to cleverly reverse the magnet, approach the sensor from the bottom, then pass through to the top, could only activate the one side. Thank you btw, not often do you get a response from someone quickly

 

[Nige]

My thoughts: will the hz function on my dmm serve me better here than the voltage setting? According to specs, output is 500hz plus/minus 80. Thats 460-540hz range

No. If the switch is the same as the Skid Steer one it is a Hall Effect switch and the output variations that are used as inputs to the ECM are seen as a variation in voltage, nothing to do with frequency.

Are you saying that the output voltage variation of the LH & RH switches are approximately the same but one switch works (as in the function it controls does what you want it to do) and yet the other one doesn't.?

 

[Billj324]

No. If the switch is the same as the Skid Steer one it is a Hall Effect switch and the output variations that are used as inputs to the ECM are seen as a variation in voltage, nothing to do with frequency.

Are you saying that the output voltage variation of the LH & RH switches are approximately the same but one switch works (as in the function it controls does what you want it to do) and yet the other one doesn't.?

I’ll confirm this tomorrow early morning, but testing both LH/RH both showed very similar readings. I wrote down the values on the problem side, but sweating it out, I forgot to write down the LH.
perhaps Im getting them [hall effect] confused. This is a newer 308E2… Im green to cat, but advanced in engineering. Got three cats to get back to purring - skid steer, the 308, and the backhoe. I think I’m gonna be on here a bit.

 

[Nige]

perhaps Im getting them [hall effect] confused. This is a newer 308E2…

A Serial Number might help. I can look at the switch on the electrical schematic.

While I think about it, when you’re measuring the output of the switch and the input to the ECM, do it by back-probing with the wiring connected. That’s the only way to get accurate results.

 

[Billj324]

I seem to remember the voltages being the same on both sides. If the LH shows closer to 1.6v/4v/6.4v v.s. RH 1.9v/4v/6.23v
Then we can probably lean towards a bad switch. Interestingly, 1.9 is further off than 6.23v.

A Serial Number might help. I can look at the switch on the electrical schematic.

While I think about it, when you’re measuring the output of the switch and the input to the ECM, do it by back-probing with the wiring connected. That’s the only way to get accurate results.

Thank you again, I’ll get you that info tomorrow morning. Moving boulders by yelling at them isnt working. Would be rewarding to figure this out

 

[Nige]

Those voltage numbers seem pretty "normal" from what I remember, although every switch can be a little bit different. AFAIK the ECM responds to a change in voltage from the switch not the actual input voltage.

Around 4.0v in the centre, and about 2.4-2.5v above/below that when the thumbwheel is rolled front and rear.

 

[Billj324]

Those voltage numbers seem pretty "normal" from what I remember, although every switch can be a little bit different. AFAIK the ECM responds to a change in voltage from the switch not the actual input voltage.

Around 4.0v in the centre, and about 2.4-2.5v above/below that when the thumbwheel is rolled front and rear.

Hit it this morning again, both sides read about the same, the variations being proportional to the input signal so, running/stopped the voltages are different.m- this is probably why they went with PWM. Both sides measured ~4v @ center, ~1.88v up, 6.22v down. So, the issue doesnt seem to be the switch (unless its PWM signal is funky - which I dont have the means to test). Im going to trace and test at the ECU.

 

[Nige]

So, the issue doesnt seem to be the switch (unless its PWM signal is funky - which I dont have the means to test).

The output of this particular switch is not PWM, it's a varying voltage as a result of the Hall Effect. Testing it using the DC range of your multimeter, provided that you are backprobing the pins with the switch still connected to the machine harness, is fine.

If it was a PWM switch (as fitted to later models) the output voltage from the switch would remain constant but the width of the output pulse would change in response to switch movement. That's where you would need a multimeter capable of measuring Duty Cycle - which is not the same as frequency.

 

[Billj324]

If it was a PWM switch (as fitted to later models) the output voltage from the switch would remain constant but the width of the output pulse would change in response to switch movement. That's where you would need a multimeter capable of measuring Duty Cycle - which is not the same as frequencyi

Thats right I was supposed to supply serial num. just got in from taking the horses for a ride. Burnt. Will get after lunch and celebrations. Its 2015/2016 308e2 is what i got for you for now

 

[Ctucker]

Could it be a a solenoid that actuates the hydraulic valve that could be an issue? Meaning, whatever the thumb wheel is telling the ECM the ECM is telling a valve or solenoid somewhere to open and close.

 

[Ctucker]

FYI…All. My thumb wheel has been working intermittently ……took it part today and found three of the wires broken inside the sheath. The wire sheaths were totally intact.