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 through the ECU data monitor function of Techstream.

1. Turn the ignition switch off and connect Techstream to the DLC3.
2. Turn the ignition switch on. Follow the on-screen directions on Techstream to display the Data List and select areas which should be monitored for momentary interruptions.

   HINT:

   A momentary interruption (open circuit) cannot be detected for 3 seconds after the ignition switch is turned on (initial check).

   ABS/VSC/TRAC 

   ABS/VSC/TRAC - DATA LIST
   
   

   Tester Display	Measurement Item/Range	Normal Condition
   FR Speed Open	Front speed sensor RH open detection/OPN_DET or NORMAL	OPN_DET: momentary interruption NORMAL: normal
   FL Speed Open	Front speed sensor LH open detection/OPN_DET or NORMAL	OPN_DET: momentary interruption NORMAL: normal
   RR Speed Open	Rear speed sensor RH open detection/OPN_DET or NORMAL	OPN_DET: momentary interruption NORMAL: normal
   RL Speed Open	Rear speed sensor LH open detection/OPN_DET or NORMAL	OPN_DET: momentary interruption NORMAL: normal
   EFI Open	SFI 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	Deceleration 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
   Accumulator Open	Accumulator pressure sensor open detection/OPN_DET or NORMAL	OPN_DET: momentary interruption NORMAL: normal

   HINT:

   • If Techstream status remains open, 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.
     Fig 1: ECU - Blinking Pattern

     Courtesy of © TOYOTA, LICENSE AGREEMENT TMS1002
3. While observing the screen, gently jiggle the connector or wire harness between the ECU and sensors, or between ECUs. If the display changes, the connector and/or wire harness will be in momentary interruption (open circuit). Repair or replace connector and/or wire harness as one of them is faulty.