A343F Solenoid Kit 2000

Owners usually land on this kit with a 2000-or-later Toyota four-speed that has started acting up: a 100-series Land Cruiser that pulls away in second, a 4Runner or Tacoma 4x4 that drops into fail-safe with the O/D OFF lamp blinking, or a truck that cruises at highway speed with the tach sitting a few hundred rpm too high because the converter never locks. The kit replaces all three valve body solenoids, the two shift solenoids and the lockup solenoid, and adds a new pan filter and pan gasket so the whole electrical side of the valve body is renewed in one service.

What the solenoid kit does in a 2000 A343F

The A343F is the 4x4 member of Aisin's A340 family, the unit behind the 100-series Land Cruiser and Lexus LX 470, with the 4Runner, Tacoma, Tundra and Sequoia 4x4s using the closely related A340F and A341F. The computer never moves a shift valve directly. It switches solenoid S1 and solenoid S2 on and off in four combinations, one per gear, and the shift valves follow the pattern. The lockup solenoid, SL, signals the lockup relay valve to apply the converter clutch in the upper gears.

Model year 2000 matters for this family because it is the changeover year. Sonnax splits the hardware into the early Type 1 valve body (casting codes 8930 and 8931) and the late Type 3 (casting 8935, V8 with electronic throttle) and Type 4 (casting 8938, V6 or V8, electronic or cable throttle). Its parts for the early design are listed through 2000 and its parts for the late design from 2000 on, so a 2000 truck can carry either. This kit is the late-style set.

Symptoms of worn S1, S2 or SL solenoids

• Takes off in second or third, or will not shift into overdrive
• No reverse, or a long pause before reverse engages
• O/D OFF light flashing and the transmission locked in one gear (fail-safe)
• Converter never locks, or locks and unlocks at steady cruise with rpm hunting
• Codes P0750 (S1 circuit), P0755 (S2 circuit) or a lockup solenoid circuit code
• Shift quality that is fine cold and gets worse after a long tow or hot traffic

How to confirm the solenoids are the problem

Rule out wiring before buying parts. A well-known 2002 Tacoma case went through a solenoid, a valve body and a computer for a P0755 with no reverse, and the cause was a loose ground bolt leaving voltage on the S2 circuit. Watch the commanded solenoid states and actual gear on a scan tool, using our guide to reading transmission live data, then check each solenoid on the bench with a multimeter test. Lockup complaints need one more step: on the late valve body, Sonnax lists lockup relay valve bore wear as a cause of TCC codes and rpm fluctuation, so a new SL solenoid will not cure lockup cycling if the valve is worn. Our TCC shudder diagnosis guide covers telling a lockup control fault from a worn converter clutch.

Fitment

This listing is the 2000 version and cross-references the A340E. The set is supplied for the late A340/A343 trucks: 2000-2004 4Runner, 2000-2004 Tacoma 4x4, 2001-2004 Sequoia and 2000-2002 Land Cruiser. Because 2000 straddles the valve body change, drop the pan and read the casting number on the valve body, or pull one solenoid and match its body, mounting tab and connector before you install. If you would rather not guess, send us the year and VIN. Early-style kits and the rest of the family's parts are in the Aisin transmission parts collection.

Install notes

• Drain the fluid and remove the pan and filter. Label each solenoid lead before unplugging, since S1, S2 and SL share a similar look.
• Coat the new O-rings with fresh ATF, seat each solenoid flat against the valve body and tighten the retaining bolt evenly. A cocked solenoid bleeds pressure.
• Clean the pan and magnets, fit the new filter and gasket, and refill with Toyota Type T-IV or the fluid the owner's manual lists for your truck. Set the level hot with the engine running.
• Clear codes and road test through all four gears and lockup. No scan-tool relearn is required for these on-off solenoids.

If the lockup circuit is your complaint, the separate 2000-2004 A343F TCC solenoid is available on its own as a spare. If the old fluid was dark or carried clutch material, plan on the A343F overhaul kit instead of solenoids alone.

My truck is a 2000. How do I know this is the right kit?

2000 is the year the A340 family moved to the late valve body, so check before you install. The late castings are 8935 and 8938; the early design is 8930 and 8931. Compare one old solenoid's body and connector with the new ones, or send us your year and VIN.

What comes in the kit?

Two shift solenoids (S1 and S2), the lockup solenoid (SL), a pan filter and a pan gasket.

Will new solenoids fix lockup that cycles on and off?

Only if the SL solenoid or its wiring is the cause. On the late valve body, wear in the lockup relay valve bore causes the same rpm fluctuation and TCC codes, and a solenoid will not fix that. Test the solenoid and the converter first.

Which fluid do I use after the install?

Toyota Type T-IV ATF, or the fluid listed in your owner's manual for that year. Check the level with the engine running and the fluid hot.

Is a relearn needed?

No scan-tool relearn is needed for these on-off solenoids. Clear the codes and road test through every gear and into lockup.

• How to Read Transmission Live Data With a Scan Tool
• How to Test a Transmission Shift Solenoid With a Multimeter
• TCC Shudder: What It Actually Is and How to Diagnose It Correctly
• Aisin Harsh or Delayed Shifts: A Diagnostic Walkthrough