Sorry, I don't know how to test or emulate the 3 pins pressure sensor, but your ABS pressure sensor appears to be out of specs. My ABS sensor always stays at zero and only increases as I apply the brake.

Have you performed these two tests in the attachment?

 

Wait a second! Does your break sensor show on scanner "0" pressure or voltage?
All scanners I use, show only voltage, it comes from "button" above break pedal, and show 0.49v when not touched/depressed.
I've tried to get pressure readings but were unable to find it.
My dad ordered whole ABS unit - used, but root might be "button" if on yours show 0v. Seems full the way depressing is 2.50v

Thank you for PDFs, 1-st one - we tested ABS sensors - all good. 2n-d one seems interesting.
However, if pressure sensor failed, seems there is no way to test it and whole unit needs to be replaced.

Thank you!

 

Both these ThinkCar scanner and Techstream are shown in either PSI or MPa.

 

It not show on mine when I use Techstream, seems time to compare what on yours and on mine, and what missing there.
Update:
not on yours:
ABS Motor Relay
Parking Brake SW
Reservoir Warning SW
SRCR
SRMF
SRMR
SMF
Master Cylinder Sensor1 (Volts)



Not on mine:
High Hydraulic Boost SW
VSC/TRAC OFF SW
SMFR
SMFL
Throttle Sensor
Master Cylinder Sensor (pressure)

What version is your Techstream, maybe mine is missing "features", too new for this year?
Will try to install same version as yours and compare - if not shown, possibly it failed component?

Thank you!

 

My version of the Techstream is 12.20.024.

Good luck!

 

Thank you!
Will try to find it and use to read.

 

Well, replaced ABS unit, and nothing changed.
I want to get back to Engine ECU, I feel that there is something that not in error list of ECU but it detects something.
Something like it is in range, but not changing as should.
I took some pics of Engine ECU live, and upstream AFR/O2 seems suspicious. Also, not really like MAF readings.

Error after replacing ABS unit.


ECU readings before start


ECU readings on idle. O2S B1S2 - Changes between 0.000v and ~0.450V


ECU readings after revving


Thank you.

 

Seems all good with readings.
I'm afraid now that ECU and SKID does not talk "clearly" to each other, and there is required to proceed with updates/calibration.
Is it possible to update w/o dealer or subscription?
There is high chance that as always they are will take $$ and do nothing - I dont trust dealers even change my wipers.
Thank you.

 

In the Techstream's health check, you could see the CAL numbers right?

I think it's time to revisit this code C1203, check the communication between the ECM and the SKID, check the wiring harness and connector for ENG+, ENG-, TRC+ and TRC-. Perform a pin drag and wiggle tests for both connectors. Good luck!

 

Thank you for hint, I already did that many times.
Next weekend planning to:
1. Get the IDs for ECU and SKID calibration.
2. Take home old/original ECU, that has been replaced long time ago, to check for missing parts (cannibalized for current ECU), and probably test circuit that was a reason for replacement (PNP detection).Put back all parts.
3. After next weekend, get back to car, connect and check ID, run tests.
4. If PNP would work, get back immobilizer chip and try to run.
If I would not be able to fix PNP error in original ECU, it will be no reason to run - PNP error will get c1203 error as well.
And next step, if nothing above will work, seems get ECU and SKID from same vehicle.
Still not understand why replaced ECU working for few months, and then decide to "talk" differently, also same for one more ECU. My only guess, one of ECU/SKID might be after updates and have calibrations not matching.

 

Calibration IDs are same - attach pic.
I put all back into old ECU and Immo chip.
Start vehicle.
Old ECU throw VSC error as well with exact same pattern (use to be only PNP switch when change to D on selector)- issue not in ECU.
Still have few hours today, will digging with wires as advised, hope will find something.
Thinking what might begin working only after starting vehicle which would cause c1203 - communication error, suspect that it might be something not in ECU/SKID error list.


Update: wiggle cables around - nothing changes.
I just find out, when review this post - it not show calibration ID for SKID.
Now I'm again out of ideas...
Thank you

 

Had not many time these weeks, but check communication wires board to board between ecu and SKID, all ok.
begin check communication line and ground on DLC3/OBD2 side, found that pin7 - k-line, have 8.5v on ignition, and 10.5 on idle, also per info i found resistance to ground should be about 120 ohm, and I have 10.28 kohm. Can someone please check actual readings on life system, on pin 7 to ground, voltage on ignition and idle, and resistance when all off.
Thank you.

 

Members of CL have been very helpful, but If it is a spec, it might be listed in the service manual.

Salim

 

As far as I search online this is only way to check if communication line not shorted and have proper voltage in the system.
Thank you

 

@mustkill
I have four Lexuses: 01, 15, 20 GS and 05 LS. The closest to your 2001 RX300 is my 2001 GS300. Here is my reading of the DLC:

Terminal 7 : ISO 9142-2 K-Line

Terminal 5 : Signal Ground

Terminal 4 : Chassis Ground

Resistance at terminal 7 and terminal 5 or terminal 4 = 0Ω

KOEO Voltage at terminal 7 and terminal 5 or terminal 4 = 0 volts

KOER Voltage at terminal 7 and terminal 5 or terminal 4 = 0 volts

Maybe someone with an RX300 can help you.

Best of luck!