Chrysler 41TE (A604) Limp Mode and Second-Gear-Only: Diagnosis and the Real Fix

Chrysler 41TE (A604) Limp Mode and Second-Gear-Only: Diagnosis and the Real Fix

Chrysler 41TE (A604) Limp Mode and Second-Gear-Only: Diagnosis and the Real Fix

You pull out of the driveway and the van feels like it launched in second. The speedometer works, reverse works, but the transmission will not shift, the MIL is on, and the scan tool is holding a fistful of transmission codes. On a Chrysler 41TE that is failsafe mode, and it is one of the most common no-start-of-day complaints on the Ultradrive family.

The mistake most people make is treating failsafe as a single failure. It is the controller giving up after it saw something it did not like, and on this unit that "something" lives in three very different places: the valve body, the clutch hardware, or a bushing that has been quietly killing a clutch pack for 20,000 miles. Here is how to tell them apart before you buy parts.

What the 41TE Actually Is (and Why That Matters)

Sonnax describes this family as beginning with the Ultradrive 4-speed automatic in 1989, and notes it was innovative for its day: clutch-to-clutch operation with no bands, plus adaptive shift technology. That single design decision drives everything below. According to Sonnax, "Because there are no bands, precise fluid control is critical for proper clutch application," with control handled by three elements: the solenoid pack, the pressure switches, and the solenoid switch valve.

Sonnax groups the related units into one branch of the family tree: the 40TE, 40TES, 41AE, 41TE, 41TES, 42LE and 42RLE. A second branch (45RFE, 545RFE, 62TE, 68RFE) uses essentially the same components in an L-shaped valve body casting - which is why a 62TE low/reverse switch valve failure reads almost identically.

Step 1: Identify the Unit Before You Touch Anything

There are multiple valve body generations under the same name, and buying for the wrong one wastes the job. Sonnax's identification guide splits them by the manual lever position sensor (MLPS): 41TE '88-'95 used an external MLPS switch; 41TE '96-'98 used an internal round pin MLPS switch; and 40TE, 41TE and 41AE from '98-later used an internal spade pin MLPS switch. The 40TES and 41TES use their own internal MLPS design.

The one you must not miss is the VLP unit. Sonnax says it is identified by the letters "VLP" cast into both the upper and lower housing, plus the addition of a pressure sensor and a pressure solenoid. From outside the transmission, look for an additional 6-pin electrical connector next to the range sensor connector. That check takes 30 seconds and changes which repair parts apply.

Step 2: Read the Codes, Then Read the Clutch Volume Indexes

Codes come first, but on this transmission the clutch volume indexes (CVIs) tell you more than the codes do. CVI is the controller's running measurement of how much fluid it takes to apply each clutch; as friction material wears, the volume climbs. Sonnax flags "High CVIs" as a symptom on this family, and calls out a high low/reverse clutch volume index (CVI over 100) as its own distinct fault signature.

So: a high L/R CVI with delayed reverse points at the low/reverse circuit, not the whole transmission. A high underdrive or overdrive CVI points at that clutch pack. Normal CVIs with failsafe codes point at the valve body or the electrical side.

Step 3: The Solenoid Switch Valve — the Most Common Single Cause

Sonnax calls the solenoid switch valve bore "perhaps the most common" wear area in these castings. Its job, per Sonnax, is to direct fluid between the low/reverse clutch and the TCC, and it also feeds the 2nd and OD clutches through two shuttle valves or "plugs" in the end of the bore.

When the bore wears, the valve and plugs stick. Sonnax lists the resulting symptoms directly: bind up, codes 841, 868, 871, 988, 1775 and 1776, engine stall, failsafe mode, no lockup, TCC apply and release concerns, and TCC codes. That is your second-gear-only complaint, spelled out.

Two critical measurement notes from Sonnax before you order anything. First, all units originally used a .420" diameter switch valve with .453" diameter plugs. Around the 2006 model year Chrysler increased the largest spool to .453" on this branch of the family, and both designs use the same plug diameter, so you must measure the switch valve itself to know which you have. Second, Sonnax warns that "Using the wrong tooling setup can result in wasted time and irreparable damage to the valve body casting." Their Solenoid Switch Valve Plug Kit 92835-02K is specified for bores containing the OE switch valve with the .420" large spool only.

Sonnax also states that while the wear is often visible, vacuum testing is the best way to determine when a repair is actually needed. Do not condemn a bore by eye.

Step 4: The Bushing That Eats Underdrive Clutches

This is the part most rebuilds miss, and it is why the same transmission comes back. In Sonnax's 41TE catalog, the Input Clutch Hub Bushing, part 92003-01K, is listed specifically to help cure premature underdrive clutch failure. Sonnax gives it as a steel-backed bimetal precision bushing, 0.575" wide, for a 1.781" shaft diameter and a 1.904" housing bore, installed with tooling 92003-TL.

Read that the right way: a worn input clutch hub bushing lets the hub run off-center, and the underdrive clutch pays for it. If you replace burned underdrive frictions and leave the bushing, you have bought yourself a second rebuild.

The same logic applies at the overdrive hub. Sonnax lists Overdrive Clutch Hub Bushings 92004-L and 92004-LOS for late-style hubs with a 1.162" shaft O.D., differing by housing bore (.937" and .941" respectively), and says they help cure planetary failure, shaft breakage, bushing failure and bushing wear. Bushings on this unit are not a detail item. They are the root cause.

A604 41TE friction clutch kit OEM B077880A for underdrive, overdrive and low/reverse clutch packs
A604 Friction Clutch Kit OEM B077880A - the friction stack that gets replaced once the burned clutch pack is identified.

Step 5: Delayed Reverse Is Its Own Repair

If the complaint is specifically delayed reverse with a high L/R CVI, Sonnax lists a Low/Reverse Piston Retainer Oil Feed Seal Kit, part 92106-01K, which helps cure delayed reverse, code 24 and code 60, and a high L/R clutch volume index over 100. Note the fitment restriction Sonnax publishes with it: it replaces early-style gaskets and is not for use with the late-design Chrysler low/reverse retainer, part number 04800255AB. Check the retainer before ordering.

The Fix: What to Replace While You Are In There

Once the pan is down and the unit is out, the marginal cost of doing it right is small. A correct 41TE job includes:

  • All friction and steel clutch plates - underdrive, overdrive, 2nd, 4th and low/reverse. Start with an A604 friction clutch kit and the matching A604 steel clutch plate kit OEM W077881A; browse the rest of the clutch packs collection for the other units in this family.
  • Bonded pistons. Rubber-to-metal bonds harden with heat and leak apply pressure. The A604/41TE/42RLE underdrive clutch piston covers the pack that fails first.
  • Every gasket and seal. An A604 overhaul gasket and seal kit is non-negotiable on a unit this dependent on clean hydraulic control.
  • Filter. The A604 filter kit OEM TF242, or another from the filters collection, goes in on every single service.
  • Input and OD clutch hub bushings. Per Sonnax, these are the parts that prevent the repeat failure.
  • Valve body reconditioning. Sonnax's Sure Cure kit SC-41TE bundles a pressure regulator sleeve, solenoid pack repair kit, accumulator piston and sleeve kit, solenoid switch valve plug kit, low/reverse piston retainer oil feed seal kit, OD clutch hub bushings, late-style input clutch hub bushing, converter regulator valve kit and pump bushing. Sonnax lists it for the 40TE, 40TES, 41AE, 41TE, 41TES and 42LE, marks it Non-VLP only, and requires tooling 92003-TL.

If you are pulling the unit anyway, an A604 master rebuild kit from the rebuild kits collection is the efficient way to buy the soft parts as one set.

Fluid: Use ATF+4, Not "Universal"

This is an adaptive, clutch-to-clutch transmission, and fluid friction characteristics are part of the shift calibration. The Chrysler specification is MS-9602, marketed as ATF+4. Mobil's product data sheet for its ATF+4 lists the Chrysler MS-9602 specification and describes it as formulated "for Chrysler vehicles, including Dodge, Plymouth, Eagle and certain Jeeps, that require a fluid meeting ATF+4 specification." A generic multi-vehicle fluid is a shift-quality complaint waiting to happen on this unit.

Cost and Effort: What You Are Signing Up For

Realistic difficulty tiers on a 41TE:

  • Fluid and filter service: beginner, roughly 1 to 2 hours. Worth doing first if the CVIs are normal and there are no hard codes.
  • Valve body removal and solenoid switch valve repair: intermediate, commonly a half day. In-vehicle work on many chassis, but it demands a vacuum tester and the correct reaming tooling. Do not attempt the bore repair without the right setup - Sonnax explicitly warns it can permanently damage the casting.
  • Full rebuild with clutch packs, bushings and pistons: advanced, typically 12 to 20 hours for a competent DIY on a transverse unit, and that assumes the cradle work goes cleanly. Most of that time is removal and installation, not teardown.

The economics usually decide themselves. If the underdrive clutch is burned and the input clutch hub bushing is worn, the transmission is already out - and at that point the soft parts cost far less than the labor you have already spent.

FAQ

Why does my 41TE start in second gear? That is failsafe mode. The controller defaults to a fixed gear after a fault. Sonnax lists both failsafe mode and "2nd gear starts" among the symptoms produced by a worn solenoid switch valve bore, so start there - but pull codes and CVIs first, because a burned clutch pack produces the same complaint.

Can I fix this by replacing the solenoid pack alone? Sometimes, but often not. The solenoid pack is only one of the three control elements Sonnax names; if the switch valve bore is worn, a new solenoid pack still cannot control the clutch it feeds. Vacuum test the bore before spending money on solenoids. For code-first diagnosis, our transmission DTC decoder guide walks through the process.

Is a 2006-and-later valve body different? Yes. Sonnax states that around the 2006 model year Chrysler changed the switch valve's largest spool diameter from .420" to .453" on the 41TE branch. Both versions use the same plug diameter, so measure the valve itself rather than assuming by year.

Sources