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 Tech stream.

1. Turn the ignition switch off and connect the Techstream to the DLC3.
2. Turn the ignition switch to ON. Follow the directions on the 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 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 condition.
     Fig 1: Identifying Momentary Interruption Blinking Pattern

     Courtesy of © TOYOTA, LICENSE AGREEMENT TMS1002

   ABS/VSC/TRC 

   ABS/VSC/TRC - DATA LIST
   
   

   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	-

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

   OK: Error display does not change. 

   HINT:

   If the display changes, the connector and/or the wire harness has caused a momentary interruption of the circuit. Repair or replace the connector and/or wire harness because one of them is faulty.

Refer to How to Proceed with Troubleshooting (See HOW TO TROUBLESHOOT ECU CONTROLLED SYSTEMS ).

Fig 2: Inspecting Connector And Wire Harness Between ECU Or Sensors

Courtesy of © TOYOTA, LICENSE AGREEMENT TMS1002