Hi All,
2004 Lexus RX 330 throwing P0717 and P0793 Codes. Car will turnover and start up fine but will not move when put into gear (drive or reverse). Check engine and VSC light on. I have replaced both of the sensors associated with the codes, as well as the battery. Wiring at the connections look fine. One other item of note is when the check engine light is on and car is shifted into drive there is a loud growling coming from the transmission. When the engine codes are reset and there is not yet a check engine light, this growl does not happen when shifting into gear.

I have tried resetting the ECU.

Does anyone have any ideas? I am at a loss...
Thanks,
Stefan

 

https://www.clublexus.com/forums/rx-...nsmission.html

 

Hey uksparky- I have already replaced the speed sensors and I am still getting the 2 codes, with absolutely no throttle response. Anythoughts?

 

As you have replaced the sensors it looks like it could be an internal trans problem ..say torque convertor or PCM/wiring.... at this point i would get the Lexus to trans shop
Any one else like to chime in...

 

Just tried checking continuity from all 4 wires to the ECM. Continuity is strong from all 4. I am wondering if the computer is fried. Does anyone know how to test this?

 

Not sure how much I can help but have some questions.

1) Using a scanner, clear codes and then please post up engine load, trottle position %, rpm, fuel trims, and engine temp. Car should be fully warmed up at idle with no AC or accessories on.

2) What is the measured DC voltage at the battery when engine is running. Car should be fully warmed up with no AC or accessories on.

3) Check the frame ground and engine ground and report results.

4) Was any work recenty done on this car and if so plz post up when and what was done.

5) Did this happen suddenly or has it been intermittent- if so plz explain.

 

Here is part of the information that you requested. Have to get back outside to gather the rest:

1) Using a scanner, clear codes and then please post up engine load, trottle position %, rpm, fuel trims, and engine temp. Car should be fully warmed up at idle with no AC or accessories on.- TBD

2) What is the measured DC voltage at the battery when engine is running. Car should be fully warmed up with no AC or accessories on.- last time voltage was tested while running it was reading 14v. This is a brand new battery.

3) Check the frame ground and engine ground and report results.-tbd

4) Was any work recenty done on this car and if so plz post up when and what was done. - no recent work completed.

5) Did this happen suddenly or has it been intermittent- if so plz explain. - This happened suddenly. Was coming home one evening and ran very low on gas, but gas station down the block that I wanted to fill up at was closed so I went home. Next start up, the throttle response was very low vsc, check engine and traction control light on. Was able to get back into the driveway and now there is no throttle response at all. As mentioned above, replaced the battery as voltage was getting very low during start up, new accelerator pedal position sensor, replaced both speed sensors and tested continuity through the wiring harness for both sensors to the ECU. Car turns over and starts up fine, but there is no response in park, neutral, drive, reverse etc. Odd growling sound coming from transmission when shifting into drive (ONLY WHEN CHECK ENGINE LIGHT IS ON...)

Will report back with other items but interested if this information tells you anything.

 

Cool, I will wait. The way I understand it is the Engine Ecm controls the engine AND transmission. Sensor feedback from the engine can affect the transmission.
Since you also replaced the "Pedal Position Sensor" please also include those readings too if your scanner will do it. You should be able to depress the gas pedal and see these numbers change. It is a "redundant" sensor if I remember, so there should be 2 sensor readings for the Pedal Sensor and they are mirror images to eachother- meaning when one reading goes up the other reading goes down as gas pedal is pressed.

Cool, looks good.

Cool, grounds are critical

Cool, this helps.
Ok so we are dealing with an new issue with no past issues to complicate things.

So at first you were able to rev the engine and move in reverse down driveway and back up to park?
How about now, can you rev the engine and see the tachometer move in a way that looks normal?

This is the part that is odd and makes me wonder if this is an electricl issue.
Don't quote me but I think I remember in the repair manual that the car's Engine ECM has a "default" mode for the transmission when it can't read sensors or something.
It changes the shift pattern and other stuff- going off the top of my head.

Very strange.

PS- Transmission making a growling sound is not good as you know. Just don't have enough info to know it's a trans issue or an engine issue or electrical issue. I fear it's the transmission but trying to have hope we are missing somethng.

 

Here's some info on the codes.
This is why I'm hoping the problem is electrical.

Noye- plz see the condition requirements to set these codes- there may be a hint in there why no tranny growling when codes are cleared.

P0717 RX330
(posted in fair use for commentary and discussion)



P0793 RX330

 

Margate330 - Car went to the shop before I was able to test the additional items above. Mechanic pointed out another issue that I had not noticed... the car will not engage the reverse gear. He says that when the car is put in reverse he can push it forward. Looking more and more like it is a transmission issue.

Let me know if this clues you into anything else....
Thanks,
Stefan

 

Hi Stefan,
My apologies but I am weak on transmissions.

All I know from what I've read in the official repair manual and also from what I've deduced and gleaned- the transmission works off pressures and these are controlled by the selenoids.
The selenoids are controlled by the Engine ECM.

Feedback for the whole system comes from the sensors you already replaced and many peripheral sensors from the engine.
Honestly, unless you want to be screwed by a shop that throws you a sky high price to cover their butts and all scenarios in case they misdiagnosed, I'd have Lexus dealer run some diagnostics or a trusted Indy who specializes on Toyota/Lexus.

Just my opinion, but you will need someone who really knows what they are doing because the codes you are getting are not "jiving" with a mechanical transmission failure in my opinion unless more tests are done and more info is discovered.

 

Thanks for the warning. Luckily car is at a mechanic who is a trusted friend. If he does not think that he can handle the job I am sure that he will suggest that we bring it elsewhere as has happened with other cars in the past. Thanks for all your time on this one!

 

Well.... mechanic found the issue.... previous leak in the sunroof caused a short in some wires which were not visible to me when checking continuity to the sensors. Great outcome considering the fears that I had for it....

 

which wires were compromised?