Toyota | Lexus | Scion



  • 📝 No Start, P0353 | Bad/Disconnected Coil | 2007 Toyota Sienna
    • Р0353 Toyota – Ignition Coil C Primary/Secondary Circuit
    • Bad ignition coil caused engine to cut off immediately after DTC has been set.
    • When trying to start the car, it starts and cuts off. Even disconnecting a bad coil didn’t allow engine to start.
Fuel Trims
📎 Wideband O2 Sensor Live Data | Toyota
  • Ref voltage is 3.3V
  • At idle or 2500 rpm readings should vary very slightly from 3.0V to 3.3V. Induce rich and lean condition and look for a quick response.
  • While driving at 25 MPH or more with above 1500 rpm, monitor sensor response. During acceleration, may read below 3.0V (fuel enrichment). During decel, may read above 3.3v (fuel cut), but readings should return to 3.3V during cruise throttle operation.
  • If sensor’s output remains at more than 3.8V, or less than 2.8V, or doesn’t change from 3.3V, ECM sets P1130.
  • If ECM sees constant 3.3V from a sensor, the circuit may be open.
  • If ECM sees more than 3.8V, or less than 2.8V, the circuit may be shorted.
  • Testing by propane. Put propane into the intake. Watch the fuel trim. If it was steady around +50%, it should sharply go down. If it doesn’t drop, then sensor is bad.
  • You cannot test a wideband sensor by connecting a scope. Neither amp nor voltage readings show any changes on the signal wires.
Catalytic Converter
  • 📚 2004-2009 Toyota Prius Catalyst, HCAC System
    • The purpose of the HC Adsorption Catalyst System (HCAC) system on the Prius is to adsorb and retain unburned hydrocarbons (HC) in the exhaust produced by the engine during and following a cold start. The stored HC is then released and purged through the warm three−way catalyst. This improves exhaust emissions at low temperatures.


  • 📝  Misfire Under Load | EGR Passages Clogged | 2011 Toyota Prius.
    • Shakes under load while driving. Changed spark plugs, MAF, O2, cleaned throttle body. No change. Took the intake manifold out. Found EGR passages inside the intake were clogged. Cleaning them fixed the problem.




📚 Shifter | 2004-2009 Prius


📝 P2440 | 2006 Toyota Tundra SR5 4.7L
  • DTC’s: P2440- 2nd switching valve stuck open bank one,
    P1441- 2nd air valve stuck open,
    P1444- 2nd air valve stuck open
    After codes are cleared, transmission shift normally until codes come back.
    Bad air pump and valves will put transmission into a limp mode, to force driver to stop and repair the car, thus preventing damage to the catalytic converter.
    The trick to avoid limp mode temporarily is to disconnect air pump connectors and clear codes. CEL will be on, but limp mode will be off.

📎 Shifting Problems | Bad ECM, Repair | 2001-2003 Toyota RAV4


📝 Transmission Calibration
  • After replacing the transmission, some Toyota will require a reset of transmission adaptation values:
    • Engine & ECT ➱ Special Functions ➱ Reset Memory [ 2010 Toyota Corolla … ]
      • If this function is not performed, transmission might shift gears very roughly.
  • After reset, perform a test drive. The transmission will perform automatic re-learn.



4WD | AWD | Transfer Case | Differential

📎 ADD Actuator | Tacoma 4WD
  • ADD Actuator failure is a common problem.
    • Possible problems are the solder joints of the ADD motor inside that require resoldering.




ABS | Traction Control

📚 Brake Hydraulic System | 2004-2009 Toyota Prius

📚 Brake Assist System | 2004-2009 Toyota Prius

📚 Regenerative Braking | 2004-2009 Toyota Prius

📚 Hybrid Braking Systems

📝 C0071 Steering Angle Sensor Malfunction | Reflash + Calibration | Subaru, Toyota, Lexus

📝 C1203 ECM Communication Circuit Malfunction | ABS Replacement | 2019 Highlander

  • Perform a Reset Memory and Test Mode procedures. Service Manual tells to match part numbers between ECM and ABS, didn’t mention calibration.

🩺 C1422, Traction Light | Stop Lamp Relay |  2010 Toyota RAV4



Power Steering

📚 Power Steering Explained | 2004-2009 Toyota Prius


📎 C1568, Power Steering Inoperative | Bad EPS ECU | Lexus RX400h


📎 VGRS (Variable Gear Ratio System) | 2008 Lexus LS460
  • VGRS ➱ Steering Angle Adjustment.
  • Steering wheel is off-center.
  • Needs calibration performed after replacing VGRS Actuator, ECU, or when steering column or gear is disconnected.





  • If the TPMS sensor cannot be programmed, try jumping pins 4 & 13 for 30 seconds (per TSB) and after removing a jumper, try programming again (2007 Camry)
  • Cars with Main and Secondary switch (or menu option)
    • Program BOTH sets of tires
      • Note: If the main or 2nd tire set isn’t programmed, programming one tire set won’t turn off the light. You have to program both sets.
    • Use odometer settings to switch from main to 2nd and vice versa (2008 Is250)
    • Or use the main tire switch under the glove box (2008 RX350)
📎 TPMS Programming | 2008 Lexus RX350
  • Activate the system (without TPMS tool?)
    • Make sure that a button underneath the glove box is in the ‘Main’ mode.
    • Repeat this for each tire (including spare):
      • Turn IGN ON and within 30 seconds deflate the next tire by at least 6psi.
      • Turn IGN OFF.
  • Initialize the system
    • Press the TPMS reset button under the steering column and continue holding for 3 seconds after the IGN is turned ON.




ECM & Immobilizer Programming

Read more ➱ Immobilizer



Airbag System 

  • B1000 Airbag assembly malfunction
    • Wrong front sensor (2006 Toyota Camry)
    • Bad SRS module
  • B1650 Occupant Classification System Fault
    • OCS: B1785 Occupant classification sensor left front collision detection (need to perform zero point calibration)
    • OCS: B1786 Occupant classification sensor right front collision detection (need to perform zero point calibration)
    • OCS ➯ Special Functions ➯ Zero Point Calibration
      • Usually needed after rear collisions
  • P3701 Lost Communication With Airbag Module (HV System)
    • 2007 Toyota Prius. Checked airbag DTC’s. Side sensor DTC. Check sensor, there was no sensor. Bought sensor. After plugging, it fixed both airbag and, after reset, HV system P3701 code.
  • Shorted Airbag
    • A case were shorted airbag has been activating horn
      • shorted airbag constantly energized the horn




  • 📝 Compressor Lock Sensor Testing | 2009 Toyota Tacoma
    • Operation
      • When the car is running and compressor is off, there should be no signal coming from the AC Lock Sensor.
      • When compressor is engaged, you should see a 0.5V AC waveform stabilizing around 3V reference.
    • Compressor Pinout
      • Pin 1 (VT)             – Magnetic Clutch control wire. Supplies 12V from MG relay (underhood fuse box)
      • Pin 2 (WHT/RED) – Lock Up Sensor signal wire. Going to AC Amplifier (behind the top of the glovebox)
      • Pin 3 (WHT)          – Permanent ground
    • Multimeter
      • Testing AC Lock Sensor with an ohmmeter doesn’t show any readings.
      • When applying 12V to the compressor clutch, AC Lock Sensor shows around 9V with AC Amplifier disconnected.
    • Oscilloscope
        • waveform shows AC Lock Sensor with compressor engaged and disengaged.


Radio & Navigation

📝 MOST Bus Diagnostics | 2015 Lexus IS250

📝 Rear DVD Display Doesn’t Work | Needs Remote Control | 2005 Toyota Sequoia
  • Even though Rear DVD Display has its own buttons, without remote control it will not operate.
📝 No Sound from Radio | Stop & Start System Malf. | 2018 Toyota Highlander
  • Radio system works together with Stop & Start System
  • If External Backup Boost Converter (Eco Run Vehicle Converter Assembly) doesn’t work (from Stop & Start System), radio will not have any sound.
  • In my case,
    • Radio didn’t have any codes.
    • Stop & Start System had a P33B3 External BBC Circuit code.
    • Connector on External Backup Boost Converter (located at the left side of engine compartment, below battery) was loose.



📝 LED Module Malfunction | New Headlight | 2018 Toyota Prius (x2)
  • Main Body DTCs:
    • B2430 LED Headlight Left Circuit Malfunction
    • B2431 LED Headlight Right Circuit Malfunction
  • The headlight has LED marker lights inside. Not serviceable. If LED lights don’t work, the whole headlight needs to be replaced.
  • The headlight might work fine, even if there is a headlight malfunction message on the dash and error codes in the Main Body ECU.
  • Good LED should generate squarewave (5Hz, 50% Duty, 0-12V)  feedback to the Main Body ECU through pin 2. If it doesn’t, ECU will store B2430 or B2431 codes.
    • If you buy an aftermarket headlight where feedback is not generated, you can buy a waveform generator and connect it to pin 2 of the headlight connector.
📝 Headlight Replacement | 2017 Toyota Prius Prime
  • Headlight with Headlight Control ECU was replaced
    • Headlight Leveling ECU: B2451 Vehicle Specifications have not been Stored
  • Used Techstream to program specifications.
    • Autel wasn’t able to do it (2017 Toyota Prius Prime).




Power Door Locks | Tailgate | Sliding Doors | Convertible Top

📎 Trunk Latch is Inoperative | Reset Codes | 2012 Toyota Sienna XLE
  • Trunk latch mechanism is inoperative. Owner had trunk lid replaced.
  • Back Door ECU had stored DTC about latch mechanism being inoperative.
  • After clearing DTC, trunk lid latch started working again.
📎 Sliding Doors Don’t Close | Touch Sensor | 2007 Toyota Sienna
  • Sliding door opens, but cannot be closed. No DTCs.
  • All switches were functional except touch switch.
    • In scan tool DATA it showed that the touch switch is OPEN. It means that the sensor is not connected.
    • Switch should be OFF (~1 kiloOhm) when not pressed by an obstacle. Should be OFF both with closed and open door.
    • Switch should be ON (~0 Ohms) when something prevents the sliding door to close.
  • Because Sliding Door ECU didn’t see any input from a touch sensor, it reasoned it unsafe to close the door, not knowing if there is any obstruction on the way.
  • New Touch Sensor fixed the issue.


🩺   Sliding Doors Inop (both) | Bad RH Sliding Door ECU | 2009 Toyota Sienna  



Driver Assistance | ADAS



Parking Assistance

Parking Sensor Calibration | Toyota
  • Advanced Parking Guidance/ ICS/ Intuitive P/A ➱  Intuitive P/A Detection/ Steering Adjustment
  • Make sure the steering wheel is positioned straight.
  • Choose corresponding replaced sensors and write angle values for them. If sensors look upwards, angle value will be positive, e.g. 4 degrees.
    • Note, if the scanner shows no communication with the computer or vehicle when trying to perform initialization, check if all the sensors are connected.
      • On a 2016 Prius left side sensor wasn’t connected, and it was losing communication on initialization.
      • It did give an “uninitialized rr side sensor” code though.
  • Waveform of a Parking Sensor that has not been calibrated on Toyota/ Lexus parking sensor angle measurement angle parking sensor angle measurement
📝 Parking Assistance Diagnosis | 2013 Lexus RX350
  • Parking assistance wiring diagram | Toyota Lexus.
  • Use data stream for sensor values.
    • “Open” = not connected. “Detect/Undetect” = connected
  • Try testing all sensors by unplugging all, and connecting them alternately to the first connector, while watching data.
    • With last rear sonar sensor (LH outer left) not connected, it showed no communication with all sensors.
    • With two last sensor not connected, it showed no communication with only last two sensors.



Pre-Collision Assist

📝 U0235 | ABS Calibration | 2019 Toyota Tacoma
  • Pre-Collision Assist had U0235 Lost communication with cruise control front distance range sensor
    • Out of curiosity, When I tried disconnecting the front millimeter-wave radar, I could connect with my scanner to neither Front Radar nor Pre-Collision Assist. That meant to me that Pre-Collision Assist operating system could be inside the radar (?).
  • No other modules had any codes. The wiring (B+, Gnd, Can Bus) checked out ok. Swapping a spare radar sensor didn’t help.
  • To fix U0235, I performed
    • ABS ➱ Reset Memory
    • ABS ➱ Test Mode
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