to reset the ecu ,s what pins on the obd2 connector do you short out. i have seen 4-12 and 4-13 being stated 4 is ground 12 and 13 are both "vendor options"

 

I had family emergency that needs help but I can check out the Service manual when I get time but If you want to wipe out stored codes this is also a possibility It is recommended that the engine ECU is reset after any engine performance modifications have been made to the vehicle, including using a higher octane fuel, to accelerate the learning of any new parameters. Resetting the ECU will also clear any stored error codes, however if you have a fault with your vehicle it is advisable that these codes are retrieved rather than wiped as they may help in diagnosing the problem.

• Make sure the ignition is turned off

• Remove the engine bay fuse box cover

• Remove the 20Amp/25Amp EFI fuse

• Remove the 15Amp ETCS fuse

• Wait 30 seconds

• Re-insert the two fuses

• Install the fuse box cover

It is also possible to reset the engine ECU by removing the battery. Please note that this method will also reset any memory settings such as radio presets, trip mileage, clock etc.

Good Luck

 

Getting back to your original question about the OBD port pins, I went thru the electrical section in the Lexus Service manual and it doesn't state anything about that just basically repeats what the above post mentioned.

I remember doing a similar procedure on an X5 Cressida to read the error codes though

What are you trying to erase? It might help to know what the code(s) are to get a solution

 

i have a scanner that works with your phone to clear errors. To fix a no cruise control, I replaced the clock spring. I had to swap the steering angle sensor from the old unit to the new unit I thought i may have to re zero it. It turned out everything seems ok, steering is good and no error codes. ( with ignition on i. rotated the steering lock to lock not sure if this achieved anything) Reading up on the steering angle sensor, info is it should be re zeroed after a wheel alignment or any change to the steering

 

To re-zero the steering angle sensor

from youtube video
1 - start with car ignition switch turned off
2 - center the steering wheel
3 - insert a jumper wire in the OBD port between pins 5 (grnd) and 13
3a - see video at 1:56 for jumper wire position
3b - double check that your OBD port is oriented the same way
the RX connector is reversed from the video

this photo is corrected for the RX


4 - turn the ignition switch to the ON position (do not start car)
5 - traction control, ABS and TPMS lights will flash
6 - wait 5 seconds and then turn ignition switch off
7 - remove jumper

 

thks dennis, i had looked at that video which states pins 4-13 to be shorted. another video showed pins 4-14. 13 and 14 are vendor. options i wasnt sure which iption is for toyota/lexus. I dont think any harm can be done by trying both. thks again

 

Tom -

Pin 4 is chassis ground. pin 5 is signal ground.
Either of these 2 pins can be used as signal ground is tied (connected) to chassis ground.

Pin 12 is for the skid control ECM and brake actuator
Pin 13 is for diagnostic mode, which has the reset function.
Pin 14 is the CAN buss, used by just about everything in the car.

So you can use either pin 4 or 5, no difference there. But use pin 13.

I like the 5 to 13 jumper shown in my photo because it makes the 2 pins that are jumpered to be one above the other, in-line with each other.

 

many thks again for clarifying the pins. Have you actually done a reset using 5-13?. if so did you notice any difference in operation? i have driven the car at low and high speeds since changing the sensor and everything seems normal without doing a reset.

 

Nice job Dennis Mik +1
I made a hand drawing in one of my thread but I been working so hard haven't had time to help.

I always recommend everyone get a scanner they can keep in the car.
Makes like so much easier for times like these. lol