Mercedes had to find a way to save on warranty claims, so it decided to make the TCU available as a separate part. Mercedes was getting hit with enormous warranty claims from all the dealers having to put in complete valve bodies. There are a number of speed sensors that are bonded to the conductive foil, and these sensors are failing along with some other components. The plan was really coming together until a very high failure rate started to kill many of the internal TCUs. With these additional costs you can see how the independent is now at a significant financial disadvantage, making it very difficult to compete with the OE. Of course, the factory-authorized rebuilder could buy the TCU alone (about $100) and re-use all the machined valve-body parts, but not the independents they were forced to buy the complete valve-body assembly. Prices ranged from about $600 to $1,800 depending on the program that was loaded. This is pretty expensive, since you have all the aluminum parts, valves, springs and solenoids. Why don’t we just buy new unlocked TCUs? OK, but initially Mercedes planned to sell the TCU only with a complete programmed and flow-tested valve body. Also, any perfectly good transmissions from the dismantlers are now pretty much worthless. Testing the transmission on a test stand is nearly impossible with commonly available equipment. Nor is it possible to rebuild the transmission in the conventional fashion for re-use, since the TCU is locked. Since the TCU is now tied to the immobilizer system of a particular vehicle, it is no longer possible to move this transmission to another vehicle. However, there are some significant side effects, especially for our industry. You check the level by opening the plug on the bottom and watch the oil drip out until it levels off at the top of the fill tube.īut wait along the way someone had a stroke of brilliance! In addition to these savings, why not couple the TCU to the vehicle’s immobilizer system, making it more difficult to steal! You can’t probe or easily tamper with the software in the TCU, since it is encased inside the transmission. Even many dipsticks have disappeared, since the transmissions are “lifetime fill.” The only way to change fluid is to drop the pan, replace the filter and pump fluid in from below. The only connections to the transmission are electrical-power supply, ground and digital-communication data lines ( Figure 2). Although some of the transmissions still have a mechanical link to the floor shifter, most no longer do. Now there are sensors, solenoids and connectors mounted directly on copper conductive films to further reduce needed wiring. I am not aware who was first to use this technology, but I have seen it for many years on Mercedes-Benz vehicles. Many of you may have seen manufacturers even begin to place the transmission control unit (TCU) inside the transmission ( Figure 1). Engine-management computers have moved from the passenger compartment to under the hood to the top of the engine to reduce wiring (copper) and assembly costs in vehicles.
0 Comments
Leave a Reply. |
Details
AuthorWrite something about yourself. No need to be fancy, just an overview. ArchivesCategories |