Shift Solenoid C Identification

[Shumba]

Good day. I own a 2006 Lexus IS250 and has done 86K miles. Recently it started indicated Check VSC, Check Engine and Traction lights on the dash board. i took the car to the local dealer for a computer check and the result was a faulty Shift Solenoid C. Can someone kindly help me with a diagram of the shift solenoids with the famous Solenoid C clearly identified. Please.

[johnatg]

Welcome to the forum - shame it's with a problem like this!

I'm afraid it's not as simple as that. Did they tell you the code they had identified? It may have been P0761 - this is described as 'Shift Solenoid "C" Performance (Shift Solenoid Valve S3)'. There is a complex test procedure starting from there.

Valve S3 is located on the Transmission valve body assembly which is inside the body of the transmission - you have to remove the transmission sump and various other bits and pieces to get to it.

If you send me a PM with your email address I could send you the relevant pages from the workshop manual. But a warning - unless you are a skilled mechanic with equipment such as a lift, an ECM system tester and a pressure tester and adapter etc,   you won't want to go there. Might be a good idea to find out if there are any automatic transmission specialists in your area?

 

[Shumba]

Thank you Johnatg.

Indeed it is the code P0761. Now, from the valve body diagram you gave, is Shift Solenoid C the one labelled Shift Solenoid Valve S3?

[Shumba]

My email is shumba@rocketmail.com

[johnatg]

As far as I can tell there isn't actually a 'shift solenoid C' - that refers to a category of operation - and depending on the results of the checking procedure the actual solenoid valve involved may be S3.

[Shumba]

Thank you very much John for your invaluable information. I managed to replace the offending solenoid and all those warning lights have disappeared. However, the car seems to drag gears when shifting and when it shifts to gear 6 at around 80km/h, the transmission suddenly shifts to safe mode (gear 3). I thought it could be that the transmission fluid is contaminated so i flushed it as much as i could with the Toyota TV 4 transmission fluid but there has not been any improvement. What could be causing this?

[johnatg]

Sorry - that's outside my experience and the manual doesn't give any clues about 'real world' symptoms - it just tells you to plug in the Intelligent tester and run a whole series of tests from there.

Maybe a word with a transmission specialist or back to the dealer for more diagnosis?

Good luck!

[Mike06lexu]

I'd love to pick your brain, I know this thread is older, but I'm having issues with my Lexus that seems no one from around here can address. She's sat at the lsst transmission shop for 10 days and returned with the same issues along with the same information returned to me I left with the shop that I had dropped her off with. I'm ASE Certified in several areas, just not transmissions. I dropped the pan and used my Autel to activate the solenoids one at a time. On the rack she'll shift out and HOLD 4th gear. On the ground and driving she goes limp. I don't understand how. My email is mikeprather1974@gmail.com. Please assist if you can. Ty

[George OC]

I just purchase a 2007 Lexus IS250 with 150k mil. I did a transmission service when I got the car because it had the same issue VSC light traction, check engine, exclamation light on. Reading through forums and other youtube videos,everyone suggested to replace TOYOTA PART N. 35290-34010 Solenoid assy.line pressure. After the service was done, I removed the ground cable from the Battery to eliminate the codes,witch it did, but after driving the car for about an hour to my surprise the codes were back on the dash, I took the car back to the mechanic and the  following error codes came up. P0761 Shift Solenoid C Stuck or Off -P2714 Pressure Control Solenoid D stuck or off. P2757 Torque Converter Clutch Pressure Control Solenoid Control Circuit  Performance stuck or off.  The unique situation with my car is that all my gears shift smoothly with no further issues.  At this point I have taken the car to a transmission mechanic and show him the codes and right away ID the problem through his years of experience he claimed that the issue is the Valve body, that needs to be replaced.  According to the mechanic, TOYOTA has poorly managed the service requirements for customers to maintain their vehicles, it's highly recommended to drain out the trans and replace the oil filter every 80k mil. because parts and other components inside this cars are not manufacture as they use too causing problems for the consumers. Through my experience when the transmission fluid was drain the fluid was super dark and had a burning smell to it, so this tells you that the previous owners did a poor job maintain the service logs on this vehicle.

I have schedule my service visit this week, so i will update everyone on the forum of the service once is done, i hope the mechanic is right and resolves my problem! 

[Texas]

Lexus telling you that it is a ‘Sealed for Life’ gearbox doesn’t help! Their version of ‘Life’ and any owners is gonna be worlds apart!

 

[Mihanicos]

Most people do not dare to even remove the oil pan of an automatic transmission. If you inderstand the principles of its operation, it is not difficult to repair it. For this you need the repair manual which will guide you step by step to disassemble it, check each component and reassemble it. 

The valve body controls the flow of oil to the various pistons to operate the right combination of clutches so the right gear is employed according to the prevailing driving conditions. The solenoids are operated by the transmission ECU to control their respective valves which in turn control the flow of oil to the various clutches.

If the valves are stuck you get a code for the respective solenoid but the solenoid may be ok. Sometimes the spring return of the valves breaks. Bebris inhibits the smooth operation of the valves causing malfunction.

So replacing a solenoid unless it is not working, it will not cure the fault.

In the valve body there are check valves made of stainless steel. Also there are more very small oil filters. If any of those check valves has got as much as a single hair in it, it will not function correctly causing clutch slipping and delay gear engagement.

So the conclusion is that you should disassemble the entire valve body and check it thoroughly. There are repair kits with all the o rings, seals, clutch assemblies, pistons, valves etc.

It is worth disassembling the entire transmission to check the various components, wear of bushes, planetary gears and above all the rubber seals of the pistons. Heat turns them into solid rubber  causing oil leaks and pressure loss resulting in clutch slipping. 

If you need any special tools, there are available. You can use compressed air to check the operation of the various clutches. 

Toyota automatic transmissions are very reliable if they are serviced and looked after regularly.

All the information is in Lexus-tech.doc.

Chris.

[Texas]

31 minutes ago, Mihanicos said:

Toyota automatic transmissions are very reliable if they are serviced and looked after regularly.

Agreed but Lexus tell you it is ‘Sealed for Life’ and are unwilling/reluctant to do anything with it at service intervals.....

[Mihanicos]

Refer them to the maintenance schedule of their cars. For my car which is " sealed for life " it is specified that the transmission oil should be changed every 6 years or 54000 miles. For severe service conditions  the time is reduced to 3 years and I cannot remember off hand the mileage.

Chris.