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The A340E is a four-speed automatic with a lockup torque converter found behind Toyota's 3.4L and 4.0L V6 and the 3.0L in older trucks. You will find it under the 4Runner, Tacoma, Tundra, T100, and the closely related unit in the Supra and Land Cruiser family. The Jeep AW4 is a cousin of the same design. It has a reputation for going 250,000-plus miles, and most of that reputation is earned. When one gives trouble, the fault is far more often a solenoid, a sensor, or neglected fluid than a worn-out gearbox.
The mistake owners make is assuming a rough shift means the transmission is done. On an A340E, a $60 speed sensor or a fluid service fixes the majority of complaints. Diagnose before you condemn it, because a healthy A340E is worth keeping.
The Most Common A340E Problems
Harsh Or Delayed Shifts
Bang shifts, a hard 1-2, or a long pause before it engages Drive or Reverse. On a high-mileage A340E this is usually old, oxidized fluid or a failing shift solenoid, not worn clutches. Service the fluid first; if the harshness remains, the solenoids are next.
No Overdrive / Stuck In 3rd
The truck will not shift into fourth (overdrive) and feels like it is revving high on the highway. Start with the simple stuff: the overdrive switch on the shifter, the O/D solenoid, and the wiring. A failed solenoid or a stuck switch is far cheaper than what people fear.
Torque Converter Lockup Problems
Shudder or flare when the converter clutch tries to lock, or the converter never locks and highway RPM stays high. This traces to the lockup solenoid, degraded fluid, or a worn converter clutch. Fluid and solenoid first, converter last.
Erratic Shifting From A Bad Speed Sensor
Random hard shifts, wrong-gear behavior, or a speedometer that drops out point at a failing vehicle speed sensor. The A340E leans on the VSS to time shifts, so a bad one makes a healthy transmission behave like a sick one. This is one of the cheapest and most common fixes.
Check A340E speed sensors
Slipping Under Load
RPM climbs without matching acceleration, usually when the fluid is low, burnt, or a clutch pack is finally worn. On a genuinely high-mileage unit this can mean a rebuild, but confirm fluid level and condition before you assume the worst.
A340E Repair Costs
| Repair | Parts | Total DIY | Total at a Shop |
|---|---|---|---|
| Vehicle speed sensor | $20 - $70 | $30 - $80 | $120 - $250 |
| Shift or lockup solenoid | $30 - $90 | $50 - $130 | $180 - $400 |
| Fluid & filter service | $40 - $90 | $60 - $120 | $150 - $300 |
| Reman valve body | $200 - $400 | $260 - $480 | $500 - $900 |
| Torque converter | $150 - $350 | — | $700 - $1,300 |
| Full rebuild | — | $800 - $1,400 (parts + your labor) | $1,800 - $2,800 |
| Used / salvage unit installed | $400 - $900 (unit) | — | $1,200 - $2,200 |
The pattern is clear: the cheap, common fixes (sensor, solenoid, fluid) are a few hundred dollars, and the transmission itself rarely needs the expensive column. Exhaust the cheap causes before you price a rebuild.
A340E Solenoids, Sensors & Rebuild Parts, Ships Same-Day
Speed sensors, shift and lockup solenoids, filters, fluid, and master rebuild kits for the A340E and its AW4 cousin. Order before 2pm Eastern and it ships the same day.
Shop A340E Parts →Codes Worth Knowing
| Code | Meaning | Usual Cause |
|---|---|---|
| P0500 | Vehicle speed sensor malfunction | Failing VSS, wiring, or connector |
| P0770 | Shift solenoid E (lockup) malfunction | Lockup solenoid or circuit |
| P0773 | Shift solenoid E electrical | Open or shorted lockup solenoid |
| P0753 / P0758 | Shift solenoid A / B electrical | Shift solenoid or harness fault |
| P0724 | Torque converter / brake switch circuit | Brake switch or lockup control fault |
Solenoid codes on this transmission are often the solenoid itself, but always inspect the connector and internal harness for ATF-soaked corrosion first. It is free to check and it sets the same codes as a dead part.
How To Keep An A340E Alive
- Service the fluid on time. The A340E uses Dexron-type ATF (Toyota Type T-IV on later applications). Fresh fluid is what carries these to a quarter million miles.
- Add a cooler if you tow. Heat is the killer. An auxiliary transmission cooler is the single best thing you can add to a truck that works.
- Fix small faults early. A dragging lockup or a flaky sensor abused for a year turns a $60 fix into clutch and converter damage.
- Do not ignore burnt fluid. Dark, varnished, burnt-smelling ATF is a warning. Service it and watch, do not just top it off.
FAQ
Is the A340E a reliable transmission?
Yes, it is one of the more durable four-speeds Toyota used. Most problems are solenoids, sensors, or neglected fluid rather than a worn-out gearbox. Maintained, it commonly clears 250,000 miles.
Why won't my A340E shift into overdrive?
Check the overdrive switch on the shifter first, then the O/D solenoid and its wiring. A stuck switch or a failed solenoid is the usual and inexpensive cause.
Can a bad speed sensor cause hard shifts on an A340E?
Yes. The transmission times its shifts off the vehicle speed sensor, so a failing VSS produces erratic and harsh shifting that mimics an internal problem. It is a cheap first thing to rule out.
Is it worth rebuilding an A340E?
Usually yes, given the platform's durability, but only after you have ruled out the cheap causes. Confirm the fluid, sensors, and solenoids before committing to a rebuild.