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.
Check For Intermittent Problems
- CHECK FOR INTERMITTENT PROBLEMS
HINT:
A momentary interruption (open circuit) in the connectors and/or wire harness between the sensors and ECUs can be detected in the ECU data list function of the Techstream.
- Turn the ignition switch off and connect the Techstream to the DLC3.
- Turn the ignition switch on (IG). Follow the directions on the Techstream to display the Data List and select areas where momentary interruption should be monitored.
HINT:
A momentary interruption (open circuit) cannot be detected for 3 seconds after the ignition switch is turned on (IG) (initial check).
Tester Display Measurement Item/Range Normal Condition Diagnostic Note FR Speed Open FR speed sensor open detection / OPN DET or NORMAL OPN DET: Momentary interruption
NORMAL: Normal- FL Speed Open FL speed sensor open detection / OPN DET or NORMAL OPN DET: Momentary interruption
NORMAL: Normal- RR Speed Open RR speed sensor open detection / OPN DET or NORMAL OPN DET: Momentary interruption
NORMAL: Normal- RL Speed Open RL speed sensor open detection / OPN DET or NORMAL OPN DET: Momentary interruption
NORMAL: Normal- EFI Open EFI communication open detection / OPN DET or NORMAL OPN DET: Momentary interruption
NORMAL: Normal- Yaw Rate Open Yaw rate sensor open detection / OPN DET or NORMAL OPN DET: Momentary interruption
NORMAL: Normal- Deceleration Open G sensor open detection / OPN DET or NORMAL OPN DET: Momentary interruption
NORMAL: Normal- Steering Open Steering angle sensor open detection / OPN DET or NORMAL OPN DET: Momentary interruption
NORMAL: Normal- Master Cylinder 1 Open Master Cylinder pressure sensor 1 open detection / OPN DET or NORMAL OPN DET: Momentary interruption
NORMAL: Normal- - Harness Signal.
Courtesy of © TOYOTA, LICENSE AGREEMENT TMS1002
HINT:
- If the status remains on (OPN DET displayed), check the continuity between the ECU and the sensors, or between ECUs.
- The OPN DET display on Techstream remains on for 1 second after the harness signal changes from momentary interruption (open circuit) to normal condition.
- While observing the screen, gently jiggle the connector or wire harness between the ECU and sensors, or between ECUs.
Courtesy of © TOYOTA, LICENSE AGREEMENT TMS1002
Result
OPN DET display does not change.
HINT:
The connector and/or wire harness will be in momentary interruption (open circuit) if the display changes. Repair or replace connector and/or wire harness as one of them is faulty.
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.