Troubleshooting — Finding short circuits
Z-GI-16prose procedureFinding short circuits
Shorts occur between the power (positive) and ground (negative) sides of a circuit. Therefore, finding a short circuit requires determining how the circuit is routed.
Circuits not connected to control unit
Circuits not connected to control unit — Examples and finding short circuit
Short (A)
SymptomFuse melts.
Finding short circuit1. Remove the fuse and main fuse of the circuit. 2. Disconnect all connectors of electrical components in the circuit. 3. Attach a voltmeter or test lamp to the fuse box and reconnect each connector, beginning nearest the power source. 4. Check the voltmeter reading or test lamp as the connectors are connected. A short has occurred where the voltmeter reading changes or the test lamp comes on.
Short (B)
SymptomMain fuse melts.
Finding short circuit(see Short (A) procedure)
Short (C)
SymptomThe motor operates regardless of whether the thermoswitch is ON or OFF when the ignition switch is ON. The fuse is not melted.
Finding short circuit(see Short (A) procedure)
Short (D)
SymptomThe main fuse melts when the ignition switch and thermoswitch are ON and the relay is operating.
Finding short circuit(see Short (A) procedure)
Circuits connected to control unit
Circuits connected to control unit — Examples and finding short circuit
Short (A)
SymptomFuse melts.
Finding short circuit1. Remove the fuse and main fuse of the circuit. 2. Disconnect all connectors of electrical components in the circuit. 3. Attach a voltmeter or test lamp to the fuse box and reconnect each connector, beginning nearest to the power source. 4. Check the voltmeter reading or test lamp as the connectors are connected. A short has occurred where the voltmeter reading changes or the test lamp comes on.
Short (B)
SymptomSolenoid A operates when the ignition switch is ON.
Finding short circuit(see Short (A) procedure)
Short (C)
SymptomThe CPU transistor burns out when the ignition switch is turned ON.
Finding short circuit(see Short (A) procedure)
Short (D)
SymptomThe CPU thinks the switch is ON because the same conditions exist as when the switch is ON.
Finding short circuit1. Attach the test lamp or voltmeter to the CPU connector. 2. Connect to the switch/sensor connector. 3. Check the voltmeter reading or test lamp. A short has occurred where the voltmeter reads 0 V or the test lamp goes out.
Short (E)
SymptomThe CPU senses the sensor to be 0Ω because the same conditions exist as when the resistance value is 0Ω. The CPU equipped with the self-diagnosis function outputs the code.
Finding short circuit(see Short (D) procedure)