Toyota Sienna Service Manual: Check for open circuit

Toyota Sienna Service Manual / Introduction / How to troubleshoot ecu controlled systems / Electronic circuit inspection procedure / Check for open circuit

(a) For an open circuit in the wire harness in Fig. 1, the resistance or voltage, as described below.

For an open circuit in the wire harness, the resistance or voltage, as described below

(b) Check the resistance.

Disconnect connectors A and C and measure
Check the resistance

Standard resistance (Fig. 2)

HINT:

Measure the resistance while lightly shaking the wire harness vertically and horizontally. If the results match the examples above, an open circuit exists between terminal 1 of connector A and terminal 1 of connector C.

(2) Disconnect connector B and measure the resistance between the terminals of the connectors.

Disconnect connector B and measure the resistance between the terminals of the connectors

Standard resistance (Fig. 3)

If the results match the examples above, an open circuit exists between terminal 1 of connector B2 and terminal 1 of connector C.

Check the voltage

(1) In a circuit in which voltage is applied to the ECU connector terminal, an open circuit can be checked by conducting a voltage check.

With each connector still connected, measure the voltage between the body ground and these terminals (in this order): 1) terminal 1 of connector A, 2) terminal 1 of connector B, and 3) terminal 1 of connector C.

Standard voltage (Fig. 4)

If the results match the examples above, an open circuit exists in the wire harness between terminal 1 of connector B and terminal 1 of connector C.

Basic inspection

(a) WHEN MEASURING RESISTANCE OF ELECTRONIC PARTS (1) Unless otherwise stated, all resistance measurements should be made at an ambient temperature of 20°C (68°F). Resistance measurements may b ...

Check for short circuit

(a) If the wire harness is ground shorted (Fig. 5), locate the section by conducting a resistance check with the body ground (below). (b) Check the resistance with the body ground. ...

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