No Engine Brake Or Overdrive

May 9, 2015

Hi I have an issue with my 2003 Auto Rav4 Nrg

there is basically no engine brake at all when off the throttle as if the car is in neutral, when you press the throttle again it slides back into gear no crunch or hard shift, also the car will never change into overdrive.

So pulled the codes from the car had 1 code a P0765 shift solenoid D malfunction.

the strange thing is if you press the button on the shift stick to turn off overdrive the engine brake works fine in 1st 2nd and 3rd

So far we have had the ECU sent off and re flashed , changed the S4 solenoid and also had the whole Valve body replaced and had the ECU adaption table cleared to re learn shift changes with the new valve body.

Still car has the exact same problem.

Have also checked with a voltmeter on pin 8 on the plug connector at the gearbox that when the Ecu requests 4th(overdrive) that 12v appears.

Anyone got any other ideas as now running out of them

July 31, 2015

Hi,

Have you figured it out yet? I am having the same exact problems except the code I am getting is p0766, which is still the s4 solenoid.

I have replaced the s4 solenoid, the valve body, and changed the fluid/filter. After doing all that I still dont have overdrive. No engine braking while OD is on; however, when OD button is off I have engine braking in 1st, 2nd, and 3rd.

I was about to send off the ecu to get rebuilt, but the person I spoke to informed me that the p0766 code isn't one of the codes that requires an ecu repair. I was told that a failing ecu would show false solenoid codes of p0750, p0753, p0755, p0758, and/or p1760. However, another vendor I emailed replied that p0766 is a false code from a failing ecm, and that he has fixed a few of these already. But now that I've read your post I am not convinced.

Have you ever had the transmission replaced? I found something that's similar to your problem with p0765, and I have uploaded a snapshot. But i guess this only happens if the transmission has been removed before. Mine has never been replaced.

Please let me know if you or anyone else reading this has found a fix. Thanks.

July 31, 2015

BTW, when i replaced the valvebody I remember that the c3 and b3 accumulator pistons and springs fell out from the top casing. However, the c1 accumulator stayed put. I believe in order to remove these accumulators air has to be pumped into the little holes. So, now I'm thinking this might be related to my problem.

At the time I had no clue what the pistons function was, and i just wanted to get them back in so i could reinstall the valve body. I found a diagram online and used it to reinstall the b3 and c3 pistons and springs. However, the pistons would not stay in place. I had a helper keep the pistons/spings in place using a piece of carboard while i put on the valvebody on. Now im thinking maybe the outer o-rings might have been worn out,which is why it didn't stay in place.

Recently, I found a diagram online showing the s4 functions to control the 3-4 shift valve to establish the 4th gear by changing over the fluid pressure applied b3 brake and c3 clutch acumulators. So, maybe the acumulator pistons, springs or orings are bad creating a leak or unbalanced pressure.

I will be ordering a replacement accumulator piston set soon and will update with the results. Seems i have to order the parts online or the dealership only so may take a while before i can replace it.