Installing Joy Stick Retarder Control

by Barry Levitt 1997 U270 6/13/06

I did not install, but I watched and it was 6 years ago. I am quite sure that the following is correct. For starters, I would call an Allison shop and get the retail price and part number for needed parts. Then Google for other sellers. Maybe some Allison parts dept will discount parts

To install joy stick in one of the blank square spaces on our side panel , two pieces of metal with a round hole in center are needed to be fabricated. Foretravel may have some in stock to fit our side dash panel. One square metal fits on top of panel, the other under panel.
Joy stick holds metal pieces in place and gives joy stick a firm mounting.

Joy stick installation is simple. Existing retard cable is removed, Allison 'Y" cable is inserted, plug back removed cable into one "Y" and plug joy stick cable into other "Y".

Brake pedal OEM retard switches are toward the front,
behind carpeted panel in front of steering, brake & throttle just above floor under dash.

Allison computer is also behind this panel on street side.
When the Allison computer is visible, make sure all cables are firmly seated in the computer connectors. (we had a 3 day repair that turned out to be a single cable that was touching the connector, but not firmly pushed in)

Adding the joy stick requires an additional relay IF you want to turn on brake lights with joy stick retard. New relay is activated by OEM retard relay on main 12 volt panel in our street side forward compartment . Relay #2 turns on brake lights.

New relay normal-open points are wired to two OEM brake light switches located forward top of street-side forward compartment. One can choose to or not-to activate brake lights when retard is active by installing a dash switch on this new cable going from OEM retard relay to OEM brake light switches. Turning off dash switch keeps Cruise Control active which can now increase throttle to keep on driving.

When we drive with retard joy stick activated and on cruise control when going down a big down hill, throttle goes to idle position, retarder turns on and brake light turn on AND cruise control drops out.

Then when the road levels out we find to our surprise we are no longer on cruise control. Brake lights will turn off cruise control and stay off.

Without brake light relay, if joy stick is left on when using cruise control: retard is off when driving, retard is on when coasting down hill and retard goes off when cruise control starts to accelerate again. If a coach does not activate brake lights with retard, cruise picks right up where it left off.

We also wired our tow car brake so it comes on with motorhome brake pedal, but not with joy stick retard.

Without joystick our motorhome activates 3-levels of retard when brake pedal is pressed. With joy stick you have 6-levels of retard without brake activation.


First you must have an existing retarder switch.

Cummins actually wants $600 for the wiring harness.

Foretravel makes theirs up themselves and sells the packet with harness and brake light relays and a few odds and ends for just under $30, including shipping.

Part # p28173 harness $15.27.


Joy Stick Module29506474


Joy Stick Switch 29521372


It is all you really need, the other parts had to do with the break light activation, which I did not use. Foretravel wants over $550 for the Joystick. I got it from a truck supply for I believe $350 with the little attached module. Bob Pete 4/7/08

Expect about $600 to have the joy stick installed. We recently added it to a 1997 U295. About $375 for the parts and $240 for labor. J.D Stevens 1997 U295 CAI 36'

I added the joystick control to my 1997 U 320. It was a unplug, plug, tie wrap, type of installation. It is the BEST modification I have done to the coach. A can't leave home without it deal. Raymond & Babette Jordan 1997 U 320

Guidelines for Selecting WTEC-III Retarder Controls

© Barry Brideau 2003-2017