T650 Error code M4404 No communication with Aux Controller

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Andy907

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Aug 21, 2022
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1
T650 Error code M4404 No communication with Aux Controller. I have checked all my fuses and switched around my relays. Cleaned all my grounds. I checked the wiring plugs, I don't see any worn wires. I suspect my Aux controller is bad but would like to confirm before I purchase one. I took the controller off, didn't see any hot spots in it. (also I can not switch into rabbit mode.). Any ideas on what to check? Do these aux controllers go bad very often?
 

Bwrcowboy

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Jul 13, 2023
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I'm having the same problem . unplugged my for a couple minutes plugged back in it worked for about 10 minutes then same thing .
 

procon

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Joined
Jul 16, 2023
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T650 Error code M4404 No communication with Aux Controller. I have checked all my fuses and switched around my relays. Cleaned all my grounds. I checked the wiring plugs, I don't see any worn wires. I suspect my Aux controller is bad but would like to confirm before I purchase one. I took the controller off, didn't see any hot spots in it. (also I can not switch into rabbit mode.). Any ideas on what to check? Do these aux controllers go bad very often?
I have the same problem. No Auxiliary function at all high speed doesn't work the horn stuck on and it's stalling out going from forward to reverse. I'm assuming it's the joystick that needs to be replaced. Any luck with yours?
 

2019 T770

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May 19, 2023
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I have a 2019 T770 had M4404 and intermittent codes. I checked harness, fuses, and continuity. Couldn't find the issue. Technician swapped the Aux Controller and it went away. Had to get it programmed by Bobcat.
 
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