A341E Solenoid Kit

If your 1993-1994 Lexus LS400, Volvo 940 or 960, or mid-1990s Mitsubishi Montero is stuck in one gear, skipping a gear on the way up, or flashing a shift solenoid code, the No. 1 and No. 2 shift solenoids are one of the first things to check. This is a new Rostra 52-9021 dual shift solenoid assembly for the A341E and its relatives: two shift solenoids mounted on one common bracket, with their leads and connectors already attached, ready to bolt onto the valve body.

What the shift solenoids do in an A341E

The A341E is a member of the Aisin A340 family of four-speed rear-wheel-drive electronic automatics. It does not pick gears with dedicated solenoids for each ratio. Instead the computer switches the No. 1 and No. 2 solenoids on and off in combination, and each on/off pattern sends line pressure to a different pair of shift valves. Four combinations give four forward gears. Lockup is handled by a separate solenoid that is not part of this assembly. Because two solenoids share the work, one weak coil or a plunger that no longer seats changes the pattern for several gears at once, which is why a single bad solenoid can make the transmission feel like it lost half its gears.

Symptoms of a failing No. 1 or No. 2 shift solenoid

• Starts in second or third gear, or holds one gear no matter what speed you reach
• A gear missing in the sequence, such as a 1-3 shift that skips second
• Harsh, late or flared shifts that come and go as the transmission warms up
• Check engine or AT light with a shift solenoid circuit code; on 1996-and-later OBD-II vehicles these usually read as shift solenoid A or B electrical faults such as P0753 or P0758
• Normal shifting returns briefly after the codes are cleared, then the fault comes back

How to confirm it before you order

Pull the codes first and note which solenoid the computer is complaining about. Then check resistance at the solenoid connector and again at the computer end of the harness; a reading that is fine at the solenoid but open or shorted at the module points to the wiring, not the part. Worn bands and clutches and pump wear are also common in this family, so check the fluid for burnt smell and heavy debris before blaming the electrics. If the unit is already slipping in every gear, a full A340-family master rebuild kit is the better spend, and the solenoids can go in during the overhaul.

Fitment

Rostra catalogs 52-9021 for the A341E, A341F, A343E, A343F and the 30-40LE across 1990-2004, and lists it under the interchange numbers 97959R, 97420AK, K72871G and 31R-401S. The vehicle fitment published for this assembly covers the 1993-1994 Lexus LS400, 1993-1997 Volvo 940 and 960, 1997 Volvo S90 and V90, 1994-1997 Mitsubishi Montero and 1997 Montero Sport. Because Aisin built these units for several automakers and changed the solenoid mounting over the years, match what is on your valve body before ordering: this kit is the style with two solenoids sharing one bracket and wired leads. Many Toyota truck units use separate bolt-in solenoids instead; for those see our A340E solenoid kit. If you are unsure, send us your year and VIN and we will check it, or browse the full Aisin transmission parts collection.

Install notes

• The solenoids are reached by dropping the pan. Note the routing of the leads and how the connectors clip in before removing the old bracket.
• Inspect the solenoid seats on the valve body for debris; a new solenoid will not seal on a scored or dirty seat.
• Torque the bracket bolts evenly and keep the leads clear of the filter and pan rail so they cannot be pinched.
• Refill with the fluid your owner's manual calls for (Dexron-type ATF on most of these applications, Toyota Type T-IV on some later Toyota units) and check the level hot.
• Clear codes and road test through all four gears and lockup.

Replace the filter and pan gasket while the pan is down. If the unit has high mileage and firm, late shifts, a TransGo 340-HD2 reprogramming kit addresses the valve body side of the same complaint.

Does the Rostra 52-9021 include both shift solenoids?

Yes. It is the dual shift solenoid assembly: the No. 1 and No. 2 shift solenoids mounted together on one bracket with their leads and connectors. The lockup solenoid is a separate part and is not included.

Will this fit my Toyota 4Runner or Tacoma?

Many Toyota truck A340E and A343F units use individual bolt-in solenoids rather than the shared bracket design. Compare your old part to the photo: if yours are two separate solenoids, use the A340E solenoid kit instead, or send us your year and VIN to confirm.

What codes point to these solenoids?

On 1996-and-later OBD-II vehicles, shift solenoid A and B electrical codes such as P0753 and P0758 are the usual ones. Earlier vehicles use the manufacturer's own blink or diagnostic codes for solenoid No. 1 and No. 2. Always check the wiring before replacing the part.

Do I need to remove the transmission to install it?

No. The solenoid assembly mounts to the valve body and is reached by dropping the transmission pan. Plan on a new filter and pan gasket and a fluid top-off.

What fluid should I use after installing it?

Use the fluid listed in your owner's manual. Most of these applications take a Dexron-type ATF, while some later Toyota units call for Toyota Type T-IV. Check the level with the fluid at operating temperature.

Is this an OEM-equivalent part?

It is made by Rostra Precision Controls and cross-references to 97959R, 97420AK, K72871G and 31R-401S, which are the numbers rebuilders use for this dual solenoid assembly.