Safety Warning

DIY auto repair can cause serious injury, fire, or vehicle damage. These guides are for informational purposes only. Always follow OEM torque specs, wear PPE, and consult a certified mechanic if you are unsure. You are solely responsible for your safety.

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HOMESERVICE MANUALSTOYOTA2008YARIS S, 4D SEDAN, AUTOMATICREPAIR AND DIAGNOSISEXTERNAL PAGESDIFFERENT CARSECTION 75 (AIR CONDITIONING SYSTEM (DIAGNOSTIC CODES & CIRCUIT TESTS))AIR CONDITIONING SYSTEMCIRCUIT TESTSBACK-UP POWER SOURCE CIRCUITPROCEDURE

2008 Toyota Yaris S, 4D Sedan, Automatic

Back-up Power Source Circuit: Procedure

2008 Toyota Yaris S, 4D Sedan, AutomaticSECTION Procedure

WARNING: This page is about a different car, the 2011 Toyota Avalon. However, it is still accessible from the selected car via links, so may be relevant.

INSPECT FUSE (A/C)

Remove the A/C fuse from the instrument panel J/B.

Fig 1: Identifying A/C Fuse
Courtesy of © TOYOTA, LICENSE AGREEMENT TMS1002

Measure the resistance according to the value(s) in the table blow.

Standard Resistance

Tester Connection	Condition	Specified Condition
A/C fuse	Always	Below 1 Ω

NG → REPLACE FUSE (A/C)

OK: Go to next step

CHECK HARNESS AND CONNECTOR (B - BODY GROUND)

Remove the A/C amplifier and disconnect the connector.

Fig 2: Identifying Air Conditioning Amplifier Connector Terminals
Courtesy of © TOYOTA, LICENSE AGREEMENT TMS1002

Measure the voltage according to the value(s) in the table blow.

Standard Voltage

Tester Connection	Condition	Specified Condition
D37-1 (B) - Body ground	Always	10 to14 V

NG → REPAIR OR REPLACE HARNESS OR CONNECTOR

OK → PROCEED TO NEXT CIRCUIT INSPECTION SHOWN IN PROBLEM SYMPTOMS TABLE

RENDER: 1.0x

NO RELATED

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When to See a Mechanic

Stop DIY work and contact a certified mechanic immediately if any of the following apply:

• You smell fuel, burning insulation, or see smoke.
• Brakes feel soft, pull hard to one side, or make grinding noises.
• The engine overheats, stalls repeatedly, or misfires under load.
• You are missing required tools, torque specs, or safe lifting equipment.
• You are not confident in the next step or safety outcome.