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.
Vehicle Speed Signal Circuit between Radio Receiver and Combination Meter: Procedure
- CHECK VEHICLE SIGNAL (OPERATION CHECK)
- Enter the "Vehicle Signal Check Mode" screen. Refer to Check Vehicle Signal Check Mode in Operation Check. Refer to OPERATION CHECK .
- While driving the vehicle, compare the "SPEED" indicator to the reading on the speedometer. Check if these readings are almost equal.
HINT:
The No. 3 meter circuit plate receives the vehicle speed signal from the skid control ECU via CAN communication. Therefore, perform the following inspection referring to values on the Data List of the skid control ECU because it is the source of the vehicle speed signal.
OK
Vehicle speed displayed on the "Vehicle Signal Check Mode" screen is almost the same as the actual vehicle speed measured using the Techstream. Refer to DATA LIST / ACTIVE TEST .
NG → See step 2
OK → See step 6
- INSPECT NO. 3 METER CIRCUIT PLATE (OUTPUT WAVEFORM)
- Check the output waveform.
Courtesy of © TOYOTA, LICENSE AGREEMENT TMS1002
- Remove the No. 3 meter circuit plate with the connector still connected.
- Connect an oscilloscope to terminal L27-7 (+S) and body ground.
- Turn the power switch on (IG).
- Turn a wheel slowly.
- Check the signal waveform according to the condition(s) in the table below.
Item Condition Measurement terminal L27-7 (+S) - Body ground Tool setting 5 V/DIV., 20 ms./DIV. Vehicle condition Wheel being rotated OK
The waveform is similar to that shown in the illustration.
HINT:
When the system is functioning normally, one wheel revolution generates 4 pulses. As the vehicle speed increases, the width indicated by (A) in the illustration narrows.
TEXT IN ILLUSTRATION*a Component with harness connected
(No. 3 Meter Circuit Plate)
NG → See step 5
OK: Go to next step
- Check the output waveform.
- INSPECT RADIO AND DISPLAY RECEIVER ASSEMBLY (INPUT WAVEFORM)
- Check the input waveform.
Courtesy of © TOYOTA, LICENSE AGREEMENT TMS1002
- Remove the radio and display receiver assembly with the connector still connected.
- Connect an oscilloscope to terminal L149-17 (SPD) and body ground.
- Turn the power switch on (IG).
- Turn a wheel slowly.
- Check the signal waveform according to the condition(s) in the table below.
Item Condition Measurement terminal L149-17 (SPD) - Body ground Tool setting 5 V/DIV., 20 ms./DIV. Vehicle condition Wheel being rotated OK
The waveform is similar to that shown in the illustration.
HINT:
When the system is functioning normally, one wheel revolution generates 4 pulses. As the vehicle speed increases, the width indicated by (A) in the illustration narrows.
TEXT IN ILLUSTRATION*a Component with harness connected
(Radio and Display Receiver Assembly)
NG → REPAIR OR REPLACE HARNESS OR CONNECTOR (RADIO AND DISPLAY RECEIVER ASSEMBLY - NO. 3 METER CIRCUIT PLATE)
OK → See step 4
- Check the input waveform.
- REPLACE RADIO AND DISPLAY RECEIVER ASSEMBLY. Refer to REMOVAL
- GO TO METER / GAUGE SYSTEM. Refer to Speed Signal Circuit
- PROCEED TO NEXT SUSPECTED AREA SHOWN IN PROBLEM SYMPTOMS TABLE. Refer to PROBLEM SYMPTOMS TABLE
NO RELATED
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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.