Would assume you are talking about a exhaust brake which may be controlled by a foot or hand switch. When on it will set the transmission to a preset gear generally 2 or maybe 4. maybe a light on the dash will illuminate and when you brake the unit the transmission will shift down a gear and help slow the coach down. If the RPMs are to high the transmission will not down shift. When going down a steep hill you may have to brake hard a couple of times to get the transmission to down shift to 2 or 3 or 4. If the hill is really steep as the RPMS raise the ECU may shift to a higher gear and you will have to brake again. We generally travel in city traffic with it on and on the highway with it off and then I turn it on when we want to come to a complete stop or slow down for some reason.
Stephen W wrote:
My neighbor just bought a new 2013 Fleetwood Expedition 40X with a 360HP Cummings and Allison transmission on a Freightliner chassis. We were talking about the "Retard" button and he said the owners manual is vague about when to use it going down grades. Does anyone here have the same driveline? He'd like some do's & don'ts and what gear the tranny needs to be in when using the retard button vs grade, how it works, etc. Thanks in advance for the responses, just trying to help a friend out before he heads to the mountains.
