Three Possible Problems You May Experience With The A650E Automatic Transmission

Posted by on Wednesday, June 26th, 2013

The A650E is a five speed automatic transmission made by Toyota and used exclusively in Lexus vehicles.  It has a very steep first gear ratio of 3.357:1 and is designed to handle a maximum of 325 horsepower, which makes it a medium duty transmission. It was first used in 1998 and remained in production through the 2005 model year. It was used in the GS300, GS400, LS 400, GS 430, IS300, RS200, SC 400 and the SC430. Although Toyota makes excellent products, here are a couple of areas where the A650E that may suffer problems.

The A650E transmission

Symptom: No lock up of the torque converter clutch.  Possible Problem: Believe it or not, this problem may be caused by the stop light switch circuit. The electrical solenoid that controls the flow of transmission fluid to the lock up clutch in the torque converter is wired in series with the brake light switch. The clutch located inside the torque converter is very small and can’t hold back much of a load. When the brakes are applied, the flow of fluid through the lock up solenoid is stopped and the clutch will disengage.  You should also run a scan check on the vehicles ECU (Engine Control Unit). The problem may be a software or hardware issue with the vehicle’s computer.

Exploded view of the A650E transmission


Symptom: The transmission will not kick down into the next lower gear at full throttle. Possible problem: The first thing you should check is the kick down circuit. There could be a loose or broken wire somewhere in the circuit.  Just like above, you should check the ECU again to see if it’s giving off any error codes.

Symptom: The transmission does not move in any gear.  Possible problem: Many issues could cause this problem. Start off by checking the transmission control rod. This is the rod that goes from the shifter to the transmission. Make sure it’s connected properly. Next, check the manual valve in the valve body. Make sure the valve moves freely with little effort. A warped valve body could be preventing the valve from moving. The next item to check is the front pump and torque converter. The easiest way to check them is to attach a pressure gauge to the pressure port on the transmissions. Refer to the shop manual for proper testing procedures and readings.  Last, drop the pan and make sure the filter/pick up tube is not clogged with debris. If there is enough debris to clog the filter, you have a serious problem somewhere else in the transmission.

The valve body in the A650E can warp causing  valves to stick

No automatic transmission is designed to last forever. Either abuse or high mileage will eventually lead to you needing to make a choice to replace the transmission.

I highly recommend that you consider replacing your transmission with a re-manufactured transmission over one that was simply rebuilt. A re-manufactured transmission will include alterations and upgrades designed to make it more durable and last longer. They will also address common issues with the transmission that the factory should have fixed in the first place. You won’t get these features in a rebuilt transmission. The re-manufactured transmission also includes a much better warranty; three years compared to an average 90 days for a rebuilt transmission.


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