Replacement push-button shift pad for Allison WTEC III controlled transmissions, covers 29538372, 29529429, 29538360, 29538371, 29538373 and 29538022.
A school bus that will not leave Neutral, a refuse truck whose D button has to be hammered three times, a dump truck with a dark range window: on an Allison run by WTEC III electronic controls, all of those point at the push button shift pad. This replacement selector is listed as 29538372 and also covers 29529429, 29538360, 29538371, 29538373 and 29538022. It has R, N and D buttons, a MODE button, up and down arrows, the single-digit range display, and a pigtail connector on the back. It measures about 6.69 x 3.15 x 1.57 inches.
WTEC III is Allison's third-generation electronic control system, and on these units the pad is the only way the driver talks to the transmission. There is no cable to the valve body. Each button press is a signal to the electronic control unit, which then picks the range and commands the solenoids. The arrows raise or lower the top range the controller will shift to, and MODE switches to the secondary shift schedule. The pad is also the built-in diagnostic screen. Allison's selector manual shows that pressing both arrows once on a WTEC III pushbutton pad starts the oil level check, which reads out as oL followed by oK, Lo or HI and a number of quarts. Pressing both arrows twice brings up the stored codes, shown one digit at a time as a main code and a sub code. So when the pad dies, the driver loses gear selection and the mechanic loses the quickest way to read the controller.
Do not replace the pad on a hunch. If the display still lights, use the double arrow press to read codes and write every one down before clearing anything. The 23-series codes listed above are the ones that point at the selector or its wiring. Codes in other families, such as 22 (speed sensors), 13 (low input voltage) or the 42 to 45 solenoid circuit codes, mean the pad is only the messenger. If the display is dead, a J1939/J1708 heavy-duty scan tool will read the controller from the diagnostic connector instead. Unplug the pad and look at the pigtail for green corrosion and spread or pushed-back pins, and check that the pad has power and ground with the key on. Our Allison limp mode guide is written for the 1000 Series, but the reasoning about why the controller holds a range after a fault applies here too.
This pad is for Allison transmissions with WTEC III controls in medium- and heavy-duty trucks, buses, and some construction and refuse equipment. It is not a pickup part: Silverado and Sierra HD trucks with the Allison 1000 use a column shift lever, not a keypad. The quickest way to tell a WTEC III pad from a later one is the display. Allison's manual sends owners of single-digit display selectors to its WTEC III section, while double-digit displays belong to the later 4th Generation controls. If yours has a double-digit window, look at the Allison 3000/4000 selector 29551555 instead. Then read the label on the back of your old pad and match it to one of the six numbers above. Body builders and bus makers mounted these in different panels, so check the connector and mount against your old unit, or send us the vehicle year, VIN and label number. More Allison parts are on the Allison collection page.
If the unit is also due for service, the two-filter Allison 3000 Series kit covers the main and lube filters on 3000 Series units.
| Replaces | 29538372, 29529429, 29538360, 29538371, 29538373, 29538022 |
| Controls | Allison WTEC III |
| Buttons | R, N, D, MODE, up arrow, down arrow, with range display |
| Dimensions | About 6.69 in x 3.15 in x 1.57 in |
Doing this repair right usually means replacing these at the same time. Same transmission, ships together.
Look at the selector display. Allison's selector manual sends single-digit display selectors to its WTEC III section and double-digit displays to the later 4th Generation section. Then match the label on the back of your old pad to 29538372, 29529429, 29538360, 29538371, 29538373 or 29538022.
On WTEC III, main code 23 covers the selector: sub code 12 is a primary shift selector fault, 13 a primary selector mode fault, 14 and 15 the secondary selector, and 16 a display line fault. Speed sensor, voltage or solenoid codes point elsewhere.
No. GM pickups with the Allison 1000 use a column shift lever. This keypad is for commercial trucks, buses and equipment with WTEC III controlled Allison transmissions.
The listing does not call for programming. It plugs into the existing pigtail. After install, confirm the display shows N at key on and that every range selects with the brake applied. If a code sets, read it before blaming the new pad.
Park level in Neutral with the parking brake set and the engine idling, then press both arrows once. The reading may wait for fluid between 140 and 220 F and about two minutes of settling. oL oK means the level is correct; Lo or HI is followed by the number of quarts off.
