My experience with Chrysler A504 / 41TE four speed automatic transmissions has been extensive, so the advice I am about to give is based on a lot of experience, but I have never actually rebuilt one myself. The free flow of fluid is mandatory in such transmissions, and one way to tell if it is getting pumped through the system is to take one of the lines off the transmission cooler, which is usually part of the radiator (unless you have a trailer towing package). Catch the fluid in a clean container but make sure it is large enough to hold all the fluid you pump out. The fluid color should be deep red (maroon) but translucent (light can go through it easily). It should not smell burned. If the fluid looks and smells okay, your problem may be the solenoid pack (possibly clogged) or the TCM itself, or the wiring between them. One transmission shop that I know of in my area has a substitution box that (temporarily) replaces the TCM, which eliminates such possible causes as bad input and output speed sensors (and their associated wiring) from causing transmission problems. The substitution box simply operates the correct solenoids in the solenoid pack (in a pulse-width modulated fashion), for each gear selected by a switch, just like the TCM normally would. Do not try to operate any solenoid in a solenoid pack by connecting it directly to a voltage source (such as 12 to 14.5 volts system voltage), nor to a system ground! If you do, you will burn the solenoid coils out in a flash! They are only meant to be pulsed at a high rate of speed, and current limited on every pulse, under TCM control. When a TCM fails in a manner that it won't pulse the solenoids in the solenoid pack any more, both units have to be replaced at the same time, or you will immediately destroy the new unit (no matter whether it is a TCM or a solenoid pack) by connecting it to an old (defective) unit. If a solenoid pack is working correctly, you should be able to hear it ratcheting (rapidly clicking) immediately after you shift the gear selector to any gear that should cause motion. Sometimes a mechanic's stethoscope is needed to hear such things in a noisy engine compartment, but such stethoscopes are cheaply obtained at most Harbor Freight stores. Chrysler A604 and 41TE transmissions are really quite beefy, and most failures are due to lack of maintenance (not changing fluid and/or filters) or abuse (using the wrong fluid and/or filters or keeping the fluid at an inadequate level). It is true, almost any liquid would work for little while. You could even put kerosene in your engine crankcase and run the engine for a very short time, but it would get really expensive, really fast, because it is not the correct fluid for the application. ATF3, ATF4 or Chrysler 7176 are your only choices for such transmissions! I have, not one, but two Dodge Grand Caravans, both of which have the four speed automatics in them. Neither has ever been rebuilt, and both have gone over 230,000 miles with any transmission problems. But one had to have a solenoid pack replaced at about 190,000 miles because of the exact same symptoms you have described on your van. Replacing input and output speed sensors are also maintenance items that, apparently, most people are unwilling to replace, so they junk their vehicles instead.
Sunday, June 19th, 2011 AT 5:28 PM