I HAVE A 2003 WITH THE ALLISON TRANNY. EVERYTHING GREAT UNTIL I ENGAGE TOW HAUL AND START DOWN A GRADE WITH THE TRAILER ATTACHED, THEN WHEN I APPLY BRAKING TO THE UNIT THE TRANSMISSION DOWN SHIFTS, MY PROBLEM IS, I HAVE TO RELEASE THE BRAKE QUICKLY OR IT WILL KEEP DOWN SHIFTING CAUSING THE ENGINE TO OVERSPEED. ANY IDEAS?
Blogs: 25 (View) Vehicle: Ford F-550, Gixxer 750, Joined: Jun 2005 Member # 103 From: Bellingham WA Visit Gallery
Posted
- July 2 2007 : 1:24p
That's normal.
The ECM knows the gear ratios, and know what road speed equates to what engine speed in that particular gear, and it will NOT let it over-rev. you're safe...just keep in in tow-haul mode, and you're set!
Blogs: 0 (Add) Vehicle: 2003 OshKosh S-Series 6x6 Joined: May 2005 Member # 86 From: Mortville WA Visit Gallery
Posted
- July 3 2007 : 11:23p
The tranny realizes you're on a hill and is trying to save you from overheating your brakes. Drive a heavy duty truck down a long steep hill and you'll know the meaning of the term "brake fade."
Allison down shift while towing
Posted - July 2 2007 : 11:21a
