Diesel Place banner

1 - 4 of 4 Posts

·
Registered
Joined
·
25 Posts
Discussion Starter #1
On my 2006 C5500 Toy Hauler, when on cruise control set to 60 mph, a drop in speed of 2 mph will trigger a down-shift. The rpm goes from 2100 to 3000 rpm - pinning you against the seat back, recovering the 2 mph in about 5 seconds, then up-shifting.

It gets really aggravating on slight grades with this continuous down-shift / up-shift pattern, until you finally turn off the cruise control. This cruise control sensitivity should be around 6 0r 7 mph. On a 2006 Allison Series 4 transmission, there seems to be no adjustment for the cruise control sensitivity.

I was wondering if anyone else is experiencing this same problem, and what mph drop from the set cruise control speed that other people's cruise controls are down-shifting.

I don't know if this is a feature or a bad ECU, or if Allison needs to write a new program to have an adjustment for the cruise sensitivity.
 

·
Registered
Joined
·
225 Posts
With the weight and wind drag of your truck,its the nature of the beast.Try 65mph with 4.78 gears at 2350 rpm.The engine can handle it,your fuel mileage will get better when you get it broke in.I tried the 60mph thing when I first bought the truck ,mine did the same thing while pulling trailers.animal rvtransporter
 

·
Registered
Joined
·
25 Posts
Discussion Starter #3
Cruise Control - Resolved!

I finally got the problem with the Allison cruise control fixed on my Gulf Stream RV. It seems that the GM factory took out the original truck program, and put in an RV program that caused it to short shift like a close-ratio gearbox with a violent engagement, only allowing a 2 mph drop in speed before down-shifting while on cruise control.

The Allison factory reprogrammed it to their "on-highway straight truck, no plow vocational 3410" program. It now shifts civilized like a wide-ratio gearbox, and allows a 4 mph drop in speed before downshifting while on cruise.

How sweet it is...
 

·
Registered
Joined
·
2 Posts
I hate to revive this thread after many years... But I've been trying to find an Allison Dealer who can do this reprogram for my Jayco Seneca Motorhome which is on a 2007 C5500 chassis. Could you share any additional details for how yoy were able to reprogram this?
 
1 - 4 of 4 Posts
Top