You pull codes on a 42RLE and the scanner throws a wall of them at once: P0750 LR solenoid, P0755 2-4 solenoid, P0760 OD solenoid, P0765 UD solenoid, plus P0841 LR pressure switch, P0846 2-4 pressure switch and P0871 OD pressure switch. The truck drops into limp-in and stays in second. The obvious move is to buy a solenoid pack and bolt it on.
Sometimes that is the right call. Very often it is not, and the shops that skip one 20-minute check end up buying the pack twice. Here is how to tell which one you have.
What the 42RLE solenoid pack actually does
The 42RLE is the rear-wheel-drive member of the Chrysler Ultradrive family that started with the A604 in 1989. Per Sonnax, that branch of the family tree covers the 40TE, 40TES, 41AE, 41TE, 41TES, 42LE and 42RLE, and all of them share the same basic control strategy. Because these units are clutch-to-clutch with no bands, fluid timing has to be precise, and Sonnax describes the control job as being split between three elements: the solenoid pack, the pressure switches, and the solenoid switch valve in the valve body.
The part most people call "the solenoid pack" is really a combined solenoid and pressure switch assembly. The solenoids move the oil. The pressure switches sit in the same housing and report back to the TCM whether a clutch circuit actually got pressure. That matters enormously for diagnosis, because a pressure switch code is not a report about an electrical part failing. It is a report that the hydraulics did not do what the computer commanded.
Read the codes correctly before you buy anything
The factory service information for P0846 (2/4 pressure switch rationality) spells out the logic. It is monitored "whenever the engine is running," and the set condition is stated plainly: "The DTC is set if one of the pressure switches are open or closed at the wrong time in a given gear. If the problem is identified for 3 successive key starts, the transmission will go into limp-in mode and the MIL will turn on after 10 seconds of vehicle operation."
Note the order of the factory cause list. Before it ever names the solenoid/pressure switch assembly, it lists the (T47) 2/4 pressure switch sense circuit open, shorted to ground, and shorted to voltage. The published thresholds for those checks are above 5.0 ohms for an open, below 5.0 ohms for a short to ground, and above 0.5 volts for a short to voltage. In other words, the manual itself tells you to prove the wiring before you condemn the pack.
Split your codes into two buckets:
- Solenoid circuit codes (P0750, P0755, P0760, P0765) point at coil resistance or the wire feeding it.
- Pressure switch rationality codes (P0841, P0846, P0871) point at a hydraulic result that did not happen, or at a sense circuit that lied about it.
When you have both buckets lit at the same time, that pattern is a clue in itself, and it points somewhere very specific.
The number one cause: the 10-pin case connector
Transmission Digest published a service item on exactly this complaint. Some 2004-05 Dodge Dakota, Durango and 300/Magnum, and 2003-05 Jeep Liberty and Wrangler models with the 42RLE exhibit multiple solenoid circuit faults including P0750, P0755, P0760 and P0765, along with P0846, P0871 and P0841 rationality codes, followed by limp mode.
The cause given is moisture in the 10-pin solenoid harness connector, which corrodes the terminals in both the case connector and the harness connector. A second cause is a wiring problem between the TCM/PCM and the transmission harness connector, and the bulletin specifically flags 04-05 Liberty models for harness chafing between the TCM/PCM.
The correction is to locate the 10-pin male and female connectors and inspect them for corrosion. If moisture or corrosion is present, install the updated pigtail. Transmission Digest lists the Dodge 10-pin harness repair kit as part number 05102405AA and the solenoid pack as 05143151AA. If the corrosion has reached the male terminals inside the solenoid pack itself, the pack has to be replaced too. If the connectors are clean, verify harness integrity back to the TCM/PCM and repair wiring as needed.
That is the whole reason to look before you buy. A green, crusty 10-pin connector will set the exact same code set as a bad pack, and a new pack plugged into a corroded connector fails again in weeks.
If the connector is clean, look at the solenoid switch valve
This is the failure that fools people, because it produces electrical-sounding codes from a purely mechanical problem. Sonnax describes the solenoid switch valve as the part that directs fluid between the low/reverse clutch and the TCC, and that also feeds the 2nd and OD clutches through two shuttle valves or plugs in the end of its bore.
As that bore wears, the valve and plugs stick. Sonnax lists the resulting symptoms directly: bind up, engine stall, failsafe mode, no lockup, TCC apply and release concerns, TCC codes, and codes 841, 868, 871, 988, 1775 and 1776. Look at that list against your scan data. P0841 and P0871 show up on both the connector-corrosion list and the worn-bore list. The connector check is what separates them.
Sonnax also notes that vacuum testing the bore is the most reliable way to decide whether the valve body needs the repair, rather than eyeballing the valve.
One critical identification step if you go this route: Sonnax states that all these units originally used a 0.420" diameter switch valve with 0.453" plugs, and that around the 2006 model year Chrysler increased the large spool of the switch valve to 0.453" in the 41TE group. Both designs use the same diameter plugs, so you have to measure the valve itself, not the plugs. Sonnax further details that the 2006 change made the small spool 0.003" smaller, the large spool 0.033" larger, and the largest land 0.040" narrower. Using the tooling for the early 0.420" design in a late 0.453" bore will, in Sonnax's words, most likely ruin the valve body, because the reamer pilot relies on that bore for support.
Know which 42RLE you have
Two more identification points save wasted parts. Per Sonnax, beginning in 2007 with the Chrysler Sebring 2.4L and 2.7L, this family got electronic line pressure control; before that the 604, 606 and 42RLE were fixed line pressure units. You can spot a variable line pressure (VLP) unit from outside the case by an extra electrical connector next to the range sensor connector, either 6-pin (early, with pin #1 unused) or 5-pin (later). Three wires run to the pressure sensor and two to the pressure solenoid, and the TCM uses that sensor as line pressure feedback to trim pressure to load.
Sonnax also notes that the VLP case has an extra hole beside the range sensor pass-through, that the pressure regulator valve becomes a one-piece anodized valve, and that the separator plate gains two extra holes. None of those parts interchange between VLP and non-VLP. Importantly for this article, Sonnax confirms the solenoid pack is still used on the VLP valve body just as it was on the non-VLP units.
On valve body part numbering, Sonnax lists CHR198 as the 42RLE with no MLPS switch and CHR402 as the 42LE/42RLE VLP with an internal MLPS switch.
When replacing the pack really is the fix
Replace the solenoid and pressure switch assembly when you have verified all of the following: the 10-pin connector and harness are clean and intact, the sense circuits pass the resistance and voltage checks in the factory procedure, and either the male terminals inside the pack are corroded or a solenoid is out of spec electrically. A pack is also the right call when corrosion has already been found in the connector and has migrated into the pack pins, which the bulletin explicitly covers.
You can shop 42RLE solenoid packs and other transmission shift solenoids here. If you are still chasing a unit that will not come out of second gear, our companion article on 42RLE limp mode and stuck in second gear walks the failsafe side of this in more detail.
Replace while you are in there
The pan has to come off either way, so do not go back in for these:
- Filter and pan gasket. A 42RLE transmission filter with gaskets is cheap insurance any time the pan is down.
- The 10-pin harness pigtail if there is any sign of moisture, even light film.
- Input and output speed sensors, which live in the same neighborhood and set their own limp-in codes.
- A valve body 42RLE shift kit if you are already pulling the valve body for the switch valve bore.
- ATF+4 only. This family is specific about fluid, and the wrong ATF changes clutch timing enough to set adaptive codes on its own.
If the fluid came out dark with friction material in the pan, the codes were downstream of a mechanical failure and a solenoid pack will not save it. That is a teardown, and a 42RLE master rebuild kit is the honest answer.
Effort and difficulty
Inspecting the 10-pin connector and testing the sense circuits is a driveway job: drop the pan, unplug and look, then back-probe with a meter. Budget an hour or two with basic hand tools and a scan tool that can show live pressure switch states.
Replacing the solenoid and pressure switch assembly is a pan-down, valve-body-accessible job on the 42RLE and is a reasonable half-day for a competent DIYer, longer in a driveway with the exhaust in the way on 4WD Wranglers. Repairing the solenoid switch valve bore is shop work: it requires the valve body out, correct identification of the 0.420" versus 0.453" valve, and the matching reamer and tooling. Do not attempt it with the wrong kit.
The mistake worth avoiding
Transmission Digest documented a case on a 545RFE, which uses the same Chrysler pressure switch strategy on the other branch of this family. The vehicle set P0871 OD pressure switch rationality. Before it reached the diagnosing shop, someone had already installed two transmissions, a replacement PCM, and at least one additional valve body and solenoid assembly. The actual fault was hydraulic, traced by watching the pressure transducer voltage fall with pressure while the OD pressure switch fluttered on and off under load. The related P0934 could set once transducer voltage fell below 0.34 volts.
Different unit, same lesson: rationality codes describe a hydraulic outcome. Prove the circuit, prove the pressure, then buy the part.
FAQ
Can I drive a 42RLE in limp mode?
Short distances at low speed only. Limp-in locks the transmission in a fixed gear to protect the clutches. The factory logic latches it after the fault repeats on three successive key starts, so a car that keeps returning to limp has an active fault, not a glitch.
Will clearing the codes fix it?
Only temporarily. The monitor runs whenever the engine is running, so a real fault re-sets the code, and the MIL comes back roughly 10 seconds into operation once the criteria are met again.
Do I need to relearn anything after replacing the solenoid pack?
Yes. These units run adaptive clutch volume learning, so shift quality will be off until the transmission relearns. Perform the quick-learn procedure with a capable scan tool and then drive it through a full range of shifts before judging the repair.
Sources
- Transmission Digest — "Dodge/Jeep 42RLE: Multiple Solenoid Circuit and Pressure Switch Faults," December 2017 Issue
- Sonnax — All in the Family: Identification & Repair of Chrysler Solenoid Switch Valve Problems
- Sonnax — Know Your Patient: How to Identify Chrysler VLP Models
- Sonnax — 42LE, 42RLE Variable Line Pressure
- Sonnax — Chrysler 42RLE Valve Body Identification
- Chrysler/Jeep service information — P0846 2/4 Pressure Switch Rationality
- Transmission Digest — Diagnosing Diagnostic Codes (P0871 / P0934 case study)