One of the biggest names in American automatic transmission manufacturing is Allison Transmission. The company was founded on September 14, 1915 by James A. Allison, although the company began as the Speedway Team Company, supporting James Allison’s Indianapolis 500 racing. In addition to automatic transmissions, they also manufacture hybrid propulsion systems and their products are used in many different markets such as bus, construction, military, distribution, and more. Historically, Allison’s most significant transmission is the CD-850 tank transmission, which it began producing in 1949. Its headquarters are located in Indianapolis, Indiana and has regional offices all over the globe. Its manufacturing facilities are located in Indianapolis, India, Hungary, Chennai, and Szentgotthard.
Limp Mode in Allison Transmissions
Modern Allison Transmissions come with a limp mode put in. This is a special shift table that permits the transmission to guard itself from harmful failure. You should always assume that this isn’t “bogus” and try and get your transmission. This limp mode locks the transmission into third gear, and keeps the torque converter from locking up. It additionally keeps the transmission from going into reverse! Keep that in mind. You don’t want to get stuck somewhere that you can’t back out of.
The limp mode is often activated by things an excessive slippage by the transmission. Here are some common conditions which will trigger a limp mode scenario.
Towing: If you are towing a heavy load (especially up a steep grade) you can often activate the limp mode. This is certainly can be an inconvenient time for this to happen. Third gear ought to pull a load quick enough on the road, however it is difficult to urge a load moving.
Excessive Heat: If the transmission overheats, that can cause it to slip as well. If you are noticing this problem during hotter weather, you may be able to keep it from happening by installing a transmission cooler. They can be found cheap on Amazon and don’t require a lot of mechanical knowledge to install. Heat issues are the number one killer of this transmission. Do your best to protect the investment.
Performance Tune: Often, when people get an engine tune they don’t realize it should really be a driveline tune. Even just a little bit extra slip put into the tune, and an Allison Transmission can have problems. So if you’ve gotten a tune recently and you’ve found your way to this page try asking if they could take the tune back to the factory specs. It should solve the issue for you.
If you’ve experienced one of the issues above, it may very well be time for a rebuild. It could be a false positive. Either way, you’ll probably want to clear the trouble codes. The best way to do so is to get a code scanner and scan the code to wipe it. It will go away after enough engine on/off cycles where the problem is no longer recognized.