850 needs new ecu??
#11
12-13-2009, 02:58 PM
Having similar problems with mine. Used it for plowing last week for the first time. Noticed that 4x4 didn't engage always when going from forward to reverse. Didn't notice the icons. Most of the time it was during hard use - putting in reverse and hitting the throttle. Seamed that if I was backing out at a slow speed it would engage. Sucks when you see both back wheels turning and nothing in front! Scheduled to take it in for the steering/front suspension recall (when parts are off backorder!) and to fix the bent Glacier II plow frame. Will have them check the ECU as well. thanks for the post.
If you accerated before the AWD came back on when switching through neutral then it is likely that the RPMS exceeded 3100 and the AWD will not come on if engaged with RPM above 3100. When you switch from forward gears to reverse or vice versa make sure the icon is on before you get the RPMS about 3100..JMO..
#12
12-13-2009, 03:02 PM
#13
12-13-2009, 03:14 PM
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Is this being exagerated because of the 1/5 revolution of rear wheels that it takes to engage the AWD?
The system is designed (all models) to only engage if there is rear wheel slippage. It automatically kicks out when stopped(newer models). It really isn't a locking system (as I've said in other posts). It locks and unlocks on it's own. I find it hard to believe that anyone would notice it though.
Just a thought.
I'm not sure who's dealer is making up stories, but I have heard of a few things with the digital wrench, updates, etc......
The system is designed (all models) to only engage if there is rear wheel slippage. It automatically kicks out when stopped(newer models). It really isn't a locking system (as I've said in other posts). It locks and unlocks on it's own. I find it hard to believe that anyone would notice it though.
Just a thought.
I'm not sure who's dealer is making up stories, but I have heard of a few things with the digital wrench, updates, etc......
#15
12-13-2009, 04:38 PM
Is this being exagerated because of the 1/5 revolution of rear wheels that it takes to engage the AWD?
The system is designed (all models) to only engage if there is rear wheel slippage. It automatically kicks out when stopped(newer models). It really isn't a locking system (as I've said in other posts). It locks and unlocks on it's own. I find it hard to believe that anyone would notice it though.
Just a thought.
I'm not sure who's dealer is making up stories, but I have heard of a few things with the digital wrench, updates, etc......
The system is designed (all models) to only engage if there is rear wheel slippage. It automatically kicks out when stopped(newer models). It really isn't a locking system (as I've said in other posts). It locks and unlocks on it's own. I find it hard to believe that anyone would notice it though.
Just a thought.
I'm not sure who's dealer is making up stories, but I have heard of a few things with the digital wrench, updates, etc......
#17
12-13-2009, 05:18 PM
The wheel slippage "sensing" is all mechanical
That is why the front and rear gear ratios are different.
#19
12-13-2009, 05:30 PM
To explain further...the XP has a rear ratio of 3.7:1 and a front ratio of 3.818:1...ie the rear is being driven slightly faster than the front...since the rear is moving the machine the front axles are turing the same speed as the rears..and therefore faster than the front differential...it is a simple overrunning clutch principle. Once the rears slip enough so that the front differential catches up to the speed of the axles the rollers in the diff ride up ramps on an inner race and wedge to an outer race connecton the diff to the side gears and thus the axles...
#20
12-13-2009, 08:19 PM
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JUst curious were you in ADC mode or just 4x4? I know I have seem mine go out when I went through Neutral...can't remember if I was in ADC at the time though,I would think not I rarely used it..
I know ADC is disabled in Neutral and Park but the manual says nothing about the 4x4 being disabled. But the service manual doas say to have it in hi or lo when checking for voltage at the AWD coil...so...who knows lol..
Like I said I never thought much about it just assumed when the selector sensor saw neutral it disabled AWD then once you hit reverse it came back on...just too a second or so.
Hopefully someoneelse will chime in. If that is the case maybe they changed that on the newer ones?? You would think that could be chaged by simple programming of the ECU?
I know ADC is disabled in Neutral and Park but the manual says nothing about the 4x4 being disabled. But the service manual doas say to have it in hi or lo when checking for voltage at the AWD coil...so...who knows lol..
Like I said I never thought much about it just assumed when the selector sensor saw neutral it disabled AWD then once you hit reverse it came back on...just too a second or so.
Hopefully someoneelse will chime in. If that is the case maybe they changed that on the newer ones?? You would think that could be chaged by simple programming of the ECU?