Check For Intermittent Problems

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 in the ECU data list function of the intelligent tester.

Turn the engine switch off and connect the intelligent tester to the DLC3.

Fig 1: Connecting Intelligent Tester To DLC3
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Turn the engine switch on (IG). Follow the directions on the intelligent tester to display the Data List and select areas where momentary interruption should be monitored.

Fig 2: Identifying Harness Signal

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 status remains on (ERROR displayed), check the continuity between the ECU and the sensors, or between ECUs.
The ERROR display on the intelligent tester remains on for 1 second after the harness signal changes from momentary interruption (open circuit) to normal condition.

DIAGNOSTIC CHART

Item (Display)	Measurement Item / Range (Display)	Normal Condition	Diagnostic Note
FR SPD OPN	FR speed sensor open detection / ERROR or NORMAL	ERROR: Momentary interruption NORMAL: Normal	-
FL SPD OPN	FL speed sensor open detection / ERROR or NORMAL	ERROR: Momentary interruption NORMAL: Normal	-
RR SPD OPN	RR speed sensor open detection / ERROR or NORMAL	ERROR: Momentary interruption NORMAL: Normal	-
RL SPD OPN	RL speed sensor open detection / ERROR or NORMAL	ERROR: Momentary interruption NORMAL: Normal	-
EFI COM OPN	EFI communication open detection / ERROR or NORMAL	ERROR: Momentary interruption NORMAL: Normal	-
YAW RATE OPN	Yaw rate sensor open detection / ERROR or NORMAL	ERROR: Momentary interruption NORMAL: Normal	-
DECELERAT OPN	Acceleration sensor open detection / ERROR or NORMAL	ERROR: Momentary interruption NORMAL: Normal	-
STEERING OPN	Steering angle sensor open detection / ERROR or NORMAL	ERROR: Momentary interruption NORMAL: Normal	-
M/C OPN	Master cylinder pressure sensor open detection / ERROR or NORMAL	ERROR: Momentary interruption NORMAL: Normal	-

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

Fig 3: Jiggle Connector Or Wire Harness Between ECU And Sensors
Courtesy of © TOYOTA, LICENSE AGREEMENT TMS1002

Result:

ERROR 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.