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 Techstream.

1. Turn the ignition switch off and connect Techstream to the DLC3.
2. Turn the ignition switch to the ON position. Follow the directions on 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 to the ON position (initial check).
   • If the status remains on (OPN DET displayed), check the continuity between the ECU and the sensors, or between EC Us.
   • 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: Identifying Blinking Pattern

     Courtesy of © TOYOTA, LICENSE AGREEMENT TMS1002

   ABS/VSC/TRAC: 

   DATA LIST
   
   

   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	Acceleration 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 open detection / OPN DET or NORMAL	OPN DET: Momentary interruption NORMAL: Normal	-

3. While observing the screen, gently jiggle the connector or wire harness between the ECU and sensors, or between ECUs.

   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 the connector and/or wire harness as one of them is faulty.