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04-30-2021, 09:30 AM
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#1
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Senior Member
Damon Owners Club
Join Date: Apr 2020
Location: Clovis NM
Posts: 4,389
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Popping out of cruise control
I don't want this to devolve into a discussion of using cruise or not using cruise please.
I use my cruise, and on long uphills, the road speed gets down to about 50, and then the cruise will disengage. This happens all the time, but only on uphills, and when the rig is slowing down because of the climb. I'm guessing it's because the transmission has run out of downshifts.
__________________
2006 Damon Daybreak 3276 35'with 5 Star Tuner. 3 200 Amp Lithium batteries and 2000 watt PSW inverter/charger. 2013 Elantra on a Master Tow dolly.
Retired USAF
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04-30-2021, 09:38 AM
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#2
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Senior Member
Join Date: Mar 2019
Location: Lansing MI
Posts: 2,825
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I think it's because of the cruise controls inability to maintain the set speed. You might want to check with the chassis or coach manufacturer, but this does not seem unreasonable to me. I might just drop my cruise setting down to about the speed you can maintain.
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An Old Fisherman
2017 Nexus Ghost 36DS, 2014 Ford F150 Long Bed
2007 Harley-Davidson Ultra Classic
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04-30-2021, 09:38 AM
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#3
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Senior Member
Join Date: Jan 2018
Location: Capistrano Beach, California
Posts: 4,465
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Quote:
Originally Posted by HarryStone
I don't want this to devolve into a discussion of using cruise or not using cruise please.
I use my cruise, and on long uphills, the road speed gets down to about 50, and then the cruise will disengage. This happens all the time, but only on uphills, and when the rig is slowing down because of the climb. I'm guessing it's because the transmission has run out of downshifts.
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My guess is that you are correct, but I have not had that experience nor have I heard of it but that's because of the reasons you don't wish to discuss. 
Am I correct is understanding that once the cruise is tripped to OFF, you then manually downshift to finish the hill climb?
__________________
Larry, Eileen, and Finley
2004 Alpine 36FDDS
Third motor home, first Alpine, no need for another.
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04-30-2021, 09:39 AM
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#4
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Senior Member
Winnebago Owners Club
Join Date: Jan 2017
Location: Las Vegas NV.
Posts: 811
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Two motor homes (gassers) and they both did it. I've had cars do it too but not as often. My current MH does it. On my cars engine vacuum was used to control throttle. I assume Gas MH engines are the same.
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Robert, Sami and our owner and boss Peanut.
2017 Winnebago Vista LX 35F. 5 Star Tune, Hellwig sway bars, Super Steer Trac Bar, 1600 Watt Solar, ARP, Spare tire carrier, Starlink, weather station, 2020 Jeep Wrangler, Ready Brute Elite. 
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04-30-2021, 09:42 AM
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#5
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Senior Member
Join Date: Apr 2011
Location: Powell River, B.C.
Posts: 31,486
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Transmission wouldn't be out of downshifts at 50 mph .
I would think it has more to do with the cruise system holding the engine at WOT ( Wide Open Throttle ) but you should get feed back from other Ford chassis owners soon , to see if the situation is normal , or if you have a one off.
EDIT: Well multiple post while I was typing ... boy I type slow.
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99DSDP 3884, Freightliner, XC, CAT 3126B, 300 HP /ALLISON 3060
2000 Caravan toad, Remco & Blue Ox.
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04-30-2021, 09:43 AM
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#6
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Registered User
Join Date: Sep 2018
Posts: 1,205
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Bad Vacuum Supply?
I have just been reading some threads on 'loss' of vacuum for gas engines and the consequences. They all were saying the engine would give trouble on long inclines, no one mentioned cruise control, but I wonder if the cruise or transmission could be tied into the vacuum system?
Common causes were rotten hoses or failed vacuum canisters.
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04-30-2021, 09:44 AM
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#7
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Registered User
Jayco Owners Club
Join Date: May 2016
Posts: 879
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I highly suspect that all vehicles do that as a safety control. My last two Chevrolet 2500's and a Ford F250 before that, and now my E450 Class C, all disengaged the cruise if the current speed approaches ~10 mph less than the set speed. This is actually mentioned in my Ford E450 owners manual. I would suggest that this is normal on yours as well. ~Craig
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04-30-2021, 10:04 AM
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#8
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Registered User
Join Date: Sep 2018
Posts: 1,205
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Another Thread on this Subject
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04-30-2021, 10:16 AM
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#9
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Senior Member
Join Date: Apr 2011
Location: Powell River, B.C.
Posts: 31,486
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Quote:
Originally Posted by OldWEB
I have just been reading some threads on 'loss' of vacuum for gas engines and the consequences. They all were saying the engine would give trouble on long inclines, no one mentioned cruise control, but I wonder if the cruise or transmission could be tied into the vacuum system?
Common causes were rotten hoses or failed vacuum canisters.
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When gas engines switched over to TPS ( Throttle Position Sensors ) and stepper motors to control the throttle body , they moved away from , throttle cables and vacuum actuated cruise systems . Speed control function now internal in the engine ECM ( Electronic Control Module ).
__________________
99DSDP 3884, Freightliner, XC, CAT 3126B, 300 HP /ALLISON 3060
2000 Caravan toad, Remco & Blue Ox.
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04-30-2021, 10:44 AM
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#10
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Senior Member
Monaco Owners Club Ford Super Duty Owner
Join Date: Dec 2008
Location: Kingsville TX
Posts: 1,754
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If you monitor the actual throttle plate opening when cruise is engaged you will notice that on ford systems the cruise control will never get to 100% WOT, cruise control only opens the throttle to approximately 85 to 90% the last 10% is when a "forced downshift" happens. Yes as other people have posted, there is a safety feature that drops the cruise control out after a 10 to 15 mph spread is seen from set speed to actual speed.
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04-30-2021, 10:51 AM
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#11
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Senior Member
Join Date: Jul 2014
Posts: 35,441
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Cruise cuts out if it senses a 10 MPH drop in speed.
Step on the gas as the speed drops, forcing a down shift, and it will hold the set speed.
Just turn up the radio, it will be singing the V10 high notes.
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05-01-2021, 07:44 AM
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#12
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Senior Member
Join Date: Feb 2013
Location: Sedona, AZ
Posts: 3,023
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Quote:
Originally Posted by twinboat
Cruise cuts out if it senses a 10 MPH drop in speed.
Step on the gas as the speed drops, forcing a down shift, and it will hold the set speed.
Just turn up the radio, it will be singing the V10 high notes.
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Exactly.
__________________
Shell Bleiweiss
2014 1/2 Thor Challenger 37KT
Sedona, AZ
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05-01-2021, 09:25 PM
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#13
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Senior Member
Damon Owners Club
Join Date: Apr 2020
Location: Clovis NM
Posts: 4,389
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Quote:
Originally Posted by twinboat
Cruise cuts out if it senses a 10 MPH drop in speed.
Step on the gas as the speed drops, forcing a down shift, and it will hold the set speed.
Just turn up the radio, it will be singing the V10 high notes.
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Tried that, it wouldn't shift down again, even with the pedal to the metal.
__________________
2006 Damon Daybreak 3276 35'with 5 Star Tuner. 3 200 Amp Lithium batteries and 2000 watt PSW inverter/charger. 2013 Elantra on a Master Tow dolly.
Retired USAF
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05-01-2021, 09:33 PM
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#14
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Senior Member
Join Date: Jul 2014
Posts: 35,441
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Quote:
Originally Posted by HarryStone
Tried that, it wouldn't shift down again, even with the pedal to the metal.
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Check with 5 star. May be left out of the time.
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