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 engine switch off.
2. Connect the Techstream to the DLC3.
3. Turn the engine 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: Identifying Techstream Display Data List

   Courtesy of © TOYOTA, LICENSE AGREEMENT TMS1002

   HINT: 

   • A momentary interruption (open circuit) cannot be detected for 3 seconds after the engine 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.
   ABS/VSC/TRAC
   
   

   Tester Display	Measurement Item/Range	Normal Condition	Diagnostic Note
   FR Speed Open	FR speed sensor open detection / ERROR or NORMAL	ERROR: Momentary interruption NORMAL: Normal	-
   FL Speed Open	FL speed sensor open detection / ERROR or NORMAL	ERROR: Momentary interruption NORMAL: Normal	-
   RR Speed Open	RR speed sensor open detection / ERROR or NORMAL	ERROR: Momentary interruption NORMAL: Normal	-
   RL Speed Open	RL speed sensor open detection / ERROR or NORMAL	ERROR: Momentary interruption NORMAL: Normal	-
   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	-
   Master Cylinder Open	Master cylinder pressure sensor 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 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 connectors and/or wire harnesses as one of them is faulty.