Safety Warning
DIY auto repair can cause serious injury, fire, or vehicle damage. These guides are for informational purposes only. Always follow OEM torque specs, wear PPE, and consult a certified mechanic if you are unsure. You are solely responsible for your safety.
Inspection Procedure
- When replacing the tire pressure warning ECU, read the transmitter IDs stored in the old ECU using a Techstream and write them down before removal.
- It is necessary to perform registration (See REGISTRATION ) of the transmitter IDs into the tire pressure warning ECU after the ECU has been replaced.
- READ VALUE USING TECHSTREAM (VEHICLE SPEED)
- Turn the ignition switch off.
- Connect a Techstream to the DLC3.
- Turn the ignition switch to ON and the tester on.
- Enter the following menus: Chassis / Tire Pressure Monitor / Data List
- Check that the values indicated on the tester and on the combination meter are the same.
Tire Pressure Monitor
TIRE PRESSURE MONITOR DATA LIST REFERENCETester Display Measurement Item/Range Normal Condition Diagnostic Note Vehicle Speed Vehicle speed/
min.: 0 km/h (0 mph)
max.: 255 km/h (158 mph)Almost same as actual vehicle speed Speed indicated on combination meter OK:
Vehicle speed indicated on the tester and on the combination meter are the same.
NG: Go to step 2
OK: USE SIMULATION METHOD TO CHECK (See HOW TO PROCEED WITH TROUBLESHOOTING )
- INSPECT TIRE PRESSURE WARNING ECU (SPD SIGNAL)
- Disconnect the D78 ECU connector.
- Jack up the vehicle.
- Move the shift lever to N.
- Turn the ignition switch to ON.
- Check the waveform of the ECU connector using an oscilloscope, while turning the wheel slowly.
Courtesy of © TOYOTA, LICENSE AGREEMENT TMS1002
OK
TESTER CONNECTION AND SPECIFIED CONDITION CHARTTester Connection Switch Condition Specified Condition D78-2 (SPD) - D78-9 (GND) Ignition switch ON Correct waveform is as shown Tool Setting
TOOL SETTINGItem Contents Tool Setting 2V/DIV., 20 ms/DIV. Vehicle Condition Rotate driving wheel slowly HINT:
- The wavelength becomes shorter as the vehicle speed increases.
- Depending on the vehicle, the output waveform voltage may rise to 12 V if influenced by optionally installed systems.
NG: Go to step 3
OK: REPLACE TIRE PRESSURE WARNING ECU (See TIRE PRESSURE WARNING ECU )
- CHECK HARNESS AND CONNECTOR (TIRE PRESSURE WARNING ECU - COMBINATION METER)
- Disconnect the D78 ECU connector.
- Disconnect the D1 meter connector.
- Measure the resistance according to the value (s) in the table below.
Standard resistance
RESISTANCE SPECIFICATIONTester Connection Condition Specified Condition D78-2 (SPD) - D1-16 (+S) Always Below 1 Ω D78-2 (SPD) - Body ground Always 10 kΩ or higher Result
RESULT CHARTResult Proceed to NG A OK (for Hatchback) B OK (for Sedan) C
Courtesy of © TOYOTA, LICENSE AGREEMENT TMS1002
B: REPLACE COMBINATION METER (See REMOVAL (for hatchback) )
C: REPLACE COMBINATION METER (See REMOVAL (for sedan) )
A: REPAIR OR REPLACE HARNESS OR CONNECTOR
NO RELATED
Use the Manual With the Right Hardware
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When to See a Mechanic
Stop DIY work and contact a certified mechanic immediately if any of the following apply:
- • You smell fuel, burning insulation, or see smoke.
- • Brakes feel soft, pull hard to one side, or make grinding noises.
- • The engine overheats, stalls repeatedly, or misfires under load.
- • You are missing required tools, torque specs, or safe lifting equipment.
- • You are not confident in the next step or safety outcome.