U151E Master Rebuild Kit

A V6 Sienna, Highlander, Camry, Solara, RAV4 or Lexus RX that flares between second and third, binds on the 3-4 shift, or slips once the fluid is hot is usually telling you the five-speed Toyota/Aisin U151E is worn out inside. This master rebuild kit is built for that unit and its close relatives (U150E, U150F and U151F). It combines three parts of a rebuild in one order: the overhaul kit of gaskets, lip seals, O-rings and sealing rings, a friction plate set, and a steel plate set. That covers every wearing clutch surface and every seal you disturb on teardown.

What a master kit does in a U151E

The U151E is the V6 version of Toyota's U-series front-drive five-speed, with ratios of 4.235, 2.360, 1.517, 1.047 and 0.756. Final drive varies by vehicle (3.291 Camry/Solara, 3.478 Highlander, 3.080 Sienna and RAV4), which is why the same kit can serve several cars. Shifts are made by linear solenoids SL1, SL2 and SL3 metering pressure to the clutches and brakes; SL1, for example, regulates the B1 brake apply on the 1-2 shift. The solenoids can only shape a clean shift if the clutch packs hold and the seals keep pressure where it belongs. Once frictions wear and sealing rings leak, the computer cannot compensate and the 2-3 shift starts to flare. Fresh frictions, steels and seals restore that holding capacity together.

Symptoms this kit addresses

• Flaring or slipping 2-3 upshift, the classic U150/U250 complaint
• Binding or tie-up on the 3-4 shift
• Slipping in one gear that gets worse as the fluid heats up
• Burnt fluid and friction debris in the pan
• Seal leaks at the axles, pan or converter on a high-mileage unit
• A shift complaint that came back after a reseal-only repair

How to confirm before you buy

GEARS magazine reports that many U150-family units with shift complaints have already had seals and solenoids replaced and still misbehave. Before ordering a kit, do the transmission memory reset with a capable scan tool, then backprobe the case connector and confirm SL1, SL2 and SL3 voltages change gear by gear. Check the computer grounds too: more than 0.1 volt on a ground wire with the engine running is a fault. A failed line pressure solenoid sets P2714, and our U151E pressure control solenoid page covers that path. If the electrical side checks out and the fluid is burnt, the clutch packs are the problem. Our guides on shift flare versus slip and harsh and delayed Aisin shifts help separate the two.

Fitment

The kit is listed for the U150E, U151E, U150F and U151F five-speed automatic transaxles. Published application data lists the U151E in the 2003-2006 Camry V6, 2004-2008 Camry Solara V6, 2004-2010 Sienna, 2004-2013 Highlander V6, 2004-2006 Lexus RX 330 and ES 330, 2005-2007 Avalon and 2006-2012 RAV4 V6. The U151F is the all-wheel-drive version in the RX 300/330/350, Sienna AWD, Highlander AWD and RAV4 V6 AWD. Four-cylinder Camry, RAV4 and Highlander models use the U241E or U250E and are not covered, and the 2007-up Camry V6 moved to the six-speed U660E. Read the code on the transmission tag, or send us your year and VIN and we will confirm. Browse more Toyota/Aisin parts on the Aisin collection page.

Install notes

• Remove the pan and valve body first and look for clutch material packed into the valve body; published failure notes say clutch debris clogs U-series valve bodies, so clean it or replace it with a U151E valve body.
• Inspect the rear cover support where the Teflon sealing rings run. Wear there drops oil pressure and burns clutch packs, so a scored support needs attention before new frictions go in.
• Check the pump, bushings and thrust washers, and replace a worn pump with the U151E pump.
• Soak the frictions in fresh fluid, set clutch clearances to factory spec, and air-check each clutch and brake.
• Refill with the fluid on your dipstick or owner's manual; most U151E vehicles call for Toyota WS.
• Finish with a memory reset and the drive cycle in our adaptive relearn guide so the computer learns the new clutch clearances.

Does this kit fit the AWD U151F?

The kit is listed for the U150E, U151E, U150F and U151F. Match the code on your transmission tag, and send us your year and VIN if you want us to confirm.

Will it fit my four-cylinder Camry or RAV4?

No. Four-cylinder models use the U241E or U250E. This kit is for the V6 U150 and U151 family only.

What does the kit include?

An overhaul kit (gaskets, seals, O-rings and sealing rings), a friction plate set and a steel plate set. Pistons, bushings, filter and hard parts are not included.

I already replaced the seals and solenoids and it still flares 2-3. Is this the fix?

Possibly, but do the transmission memory reset and the SL1, SL2 and SL3 voltage checks first. If those pass and the fluid is burnt, worn clutch packs are the likely cause.

What fluid should I use?

Use the fluid on your dipstick or in the owner's manual. Most U151E vehicles specify Toyota WS.

• Shift flare vs slip: the difference
• Aisin harsh and delayed shifts
• Adaptive relearn after a valve body or rebuild
• Aisin slipping under load