Check For Intermittent Problems

HINT: 

A momentary interruption (open circuit) in the connectors and/or wire harness between the sensors and ECUs can be monitored using the ECU data monitor 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. Enter the following menus: Chassis / ABS/VSC/TRAC / Data List.
6. Select areas where momentary interruption should be monitored.
   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	-
   EFI Communication Open	ECM 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	Deceleration 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 circuit detection / Error or Normal	Error: Momentary interruption Normal: Normal	-
   IG Voltage Value Decreased	IG voltage value decreased detection / Error or Normal	Error: Momentary interruption Normal: Normal	-
   IG Voltage Value Increased	IG voltage value increased detection / Error or Normal	Error: Momentary interruption Normal: Normal	-
   FR Speed Sensor Voltage Open	Front speed sensor RH voltage open circuit detection / Error or Normal	Error: Momentary interruption Normal: Normal	-
   FL Speed Sensor Voltage Open	Front speed sensor LH voltage open circuit detection / Error or Normal	Error: Momentary interruption Normal: Normal	-
   RR Speed Sensor Voltage Open	Rear speed sensor RH voltage open circuit detection / Error or Normal	Error: Momentary interruption Normal: Normal	-
   RL Speed Sensor Voltage Open	Rear speed sensor LH voltage open circuit detection / Error or Normal	Error: Momentary interruption Normal: Normal	-
   M/C Pressure Sensor Noise	Master cylinder pressure sensor noise detection / Error or Normal	Error: Momentary interruption Normal: Normal	-
   Yaw Rate Sensor Voltage Open	Yaw rate and acceleration sensor voltage open circuit detection / Error or Normal	Error: Momentary interruption Normal: Normal	-
   EFI Communication Invalid	ECM communication invalid detection / Error or Normal	Error: Momentary interruption Normal: Normal	-

   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 on, check the continuity between the ECU and the sensors, or between ECUs.
   • The Error display remains on for 1 second after the harness signal changes from momentary interruption (open circuit) to normal condition.
     Fig 1: Identifying Harness Signal Blinking Pattern

     Courtesy of © TOYOTA, LICENSE AGREEMENT TMS1002
7. 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. Repair or replace there is a momentary interruption (open circuit) in the connector and/or wire harness, as one of them is faulty.
   Fig 2: Checking Connector And Wire Harness

   Courtesy of © TOYOTA, LICENSE AGREEMENT TMS1002