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 using the ECU Data List function of the Techstream.

1. Turn the ignition switch off.
2. Connect the Techstream to the DLC3.
3. Turn the ignition switch to ON.
4. Turn the Techstream on.
5. Follow the directions on the Techstream to display the Data List and select areas where momentary interruption should be monitored.
   Fig 1: Identifying Momentary Interruptions In Waveform

   Courtesy of © TOYOTA, LICENSE AGREEMENT TMS1002

   HINT: 

   • A momentary interruption (open circuit) cannot be detected for 3 seconds after the ignition switch is turned to ON (initial check).
   • If the status remains on (Error displayed), check the continuity between the ECU and the sensors, or between ECUs.
   • The Error display on the Techstream remains on for 1 second after the harness signal changes from momentary interruption (open circuit) to normal.
   ABS/VSC/TRAC
   
   

   Tester Display	Measurement Item/Range	Normal Condition	Diagnostic Note
   EFI Communication Open	EFI communication open detection / Error or Normal	Error: Momentary interruption Normal: Normal	-
   Yaw Rate Open	Yaw rate sensor open detection / Error or Normal	Error: Momentary interruption Normal: Normal	-
   Deceleration Open	Acceleration sensor open detection / Error or Normal	Error: Momentary interruption Normal: Normal	-
   Steering Open	Steering angle sensor open detection / Error or Normal	Error: Momentary interruption Normal: Normal	-
   IG Voltage Value Decreased	IG voltage value decrease detection / Error or Normal	Error: Decrease Normal: Normal	-
   FR Speed Sensor Voltage Open	Front speed sensor RH voltage open detection / Error or Normal	Error: Momentary interruption Normal: Normal	-
   FL Speed Sensor Voltage Open	Front speed sensor LH voltage open detection / Error or Normal	Error: Momentary interruption Normal: Normal	-
   RR Speed Sensor Voltage Open	Rear speed sensor RH voltage open detection / Error or Normal	Error: Momentary interruption Normal: Normal	-
   RL Speed Sensor Voltage Open	Rear speed sensor LH voltage open detection / Error or Normal	Error: Momentary interruption Normal: Normal	-

6. While observing the screen, gently jiggle the connector or wire harness between the ECU and sensors, or between ECUs.
   Fig 2: Jiggling Connector Or Wire Harness Between ECU And Sensors

   Courtesy of © TOYOTA, LICENSE AGREEMENT TMS1002

   OK

   Normal display appears.

   HINT: 

   The connector and/or wire harness has a momentary interruption (open circuit) if the display changes. Repair or replace the connector and/or wire harness as one of them is faulty.