How to Shift a 13 Speed Transmissionby Rob Harris
Most trucks use a basic shift pattern in the form of an "H," based on the the standard five-speed transmission cars use. Trucks using 13-speed transmissions allow certain gears to have high and low settings, so you'll use the same gear position more than once after pushing a button to change the setting. With a 13-speed transmission, the gears are closer together than in a 10-speed transmission, for example. This allows for a split of about 17 percent between gears in a 13-speed instead of a 35 percent split on a 10-speed transmission. The smaller increments create engine efficiency and save on fuel because you don't have to run your RPMs as high before you shift. A 13-speed transmission also gives you more control of your truck when hauling heavy loads.
Shift normally through the first five gears, just as you would in a manual-transmission car or a 10-speed transmission truck.
Press the "High/Low Gear" button on your gear shift. This will change your gear locations into high gear. Move into second-gear position. This will change you into sixth gear.
Press the "Overdrive" button on your gear shift as you prepare to switch to seventh gear. Release the throttle, and the truck will shift up one gear.
Release the "Overdrive" button and move the gear shift to third-gear position. This will put you in eighth gear. Press the "Overdrive" button and release the throttle to move to ninth gear. Repeat this pattern through the rest of the gears, remembering to skip first-gear position.
Downshift by releasing the "Overdrive" button and releasing the throttle, moving the gear shift down when necessary--just like shifting up, but in reverse. Once you get to the lower gears, lower the "High/Low Gear" button and shift from gear five to one normally.
- photo_camera semi truck image by max blain from Fotolia.com