Check For Intermittent Problems

HINT: 

A momentary interruption (open circuit) in the connectors and/or wire harnesses between the sensors and ECUs can be detected using the ECU Data List function of the Techstream.

1. Turn the power switch off.
2. Connect the Techstream to the DLC3.
3. Turn the power switch on (IG).
4. Turn the Techstream on.
5. Follow the directions on the Techstream to display the Data List and select areas where momentary interruptions should be monitored.
   Fig 1: Checking For Interruptions

   Courtesy of © TOYOTA, LICENSE AGREEMENT TMS1002

   HINT: 

   • A momentary interruption (open circuit) cannot be detected for 3 seconds after the power switch is turned on (IG) (initial check).
   • If the Error display remains displayed, check for continuity between the ECUs and the sensors, or between ECUs.
   • The Error display on the Techstream will remain displayed for 1 second after the harness signal changes from momentary interruption (open circuit) to normal condition.
   TEXT IN ILLUSTRATION
   
   

   *a	Harness Signal
   *b	Momentary Interruption
   *c	OK
   *d	NG
   *e	1 sec.
   *f	Techstream Display
   *g	Error
   *h	Normal

   ABS/VSC/TRAC
   
   

   Tester Display	Measurement Item/Range	Normal Condition	Diagnostic Note
   FR Speed Open	Front speed sensor RH open detection / Error or Normal	Error: Momentary interruption Normal: Normal	-
   FL Speed Open	Front speed sensor LH open detection / Error or Normal	Error: Momentary interruption Normal: Normal	-
   RR Speed Open	Rear speed sensor RH open detection / Error or Normal	Error: Momentary interruption Normal: Normal	-
   RL Speed Open	Rear speed sensor LH 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	-
   Master Cylinder Open	Regulator pressure sensor open detection / Error or Normal	Error: Momentary interruption Normal: Normal	-
   Stroke Open	Brake pedal stroke sensor open detection / Error or Normal	Error: Momentary interruption Normal: Normal	-
   FR Wheel Cylinder Open	Wheel cylinder pressure sensor open detection / Error or Normal	Error: Momentary interruption Normal: Normal	-
   Accumulator Open	Accumulator pressure sensor open detection / Error or Normal	Error: Momentary interruption Normal: Normal	-
   HV Communication Open	Hybrid vehicle communication open detection / Error or Normal	Error: Momentary interruption Normal: Normal	-

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

   Courtesy of © TOYOTA, LICENSE AGREEMENT TMS1002

   OK

   Normal display appears.

   HINT: 

   If the display changes, this indicates that there has been a momentary interruption (open circuit) in the connector and/or wire harness. In this case, repair or replace the connectors and/or wire harnesses as one of them is faulty.