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 MANUALSTOYOTA2004MATRIX XR, FWD, STANDARDREPAIR AND DIAGNOSISEXTERNAL PAGESDIFFERENT CARSECTION 515 (MULTIPLEX COMMUNICATION SYSTEM - DIAGNOSIS)DTC B1248: AVC-LAN COMMUNICATION IMPOSSIBLEINSPECTION PROCEDURE

2004 Toyota Matrix XR, FWD, Standard

Inspection Procedure

2004 Toyota Matrix XR, FWD, StandardSECTION Inspection Procedure

WARNING: This page is about a different car, the 2004 Toyota Prius. However, it is still accessible from the selected car via links, so may be relevant.

CHECK OPERATION
1. Check that the radio and player switch can operate normally.
  OK: Radio and player switch can operate normally.
NG: Go to AUDIO SYSTEM (See HOW TO PROCEED WITH TROUBLESHOOTING )

OK: Go to next step.

CHECK RESISTANCE OF COMMUNICATION LINE

Disconnect the R5, M13 and G1 ECU connectors.

Measure the resistance between the wire harness side connectors.

Standard:

TESTER CONNECTION'S SPECIFIED CONDITION

Tester Connection	Specified Condition
R5-9 (TX+) - M13-18 (TX2+)	Below 1 Ω
R5-10 (TX-) - M13-19 (TX2-)	Below 1 Ω
M13-4 (TX1+) - G1-6 (GTX+)	Below 1 Ω
M13-5 (TX1-) - G1-21 (GTX-)	Below 1 Ω

Fig 1: Identifying R5, M13 & G1 ECU Connectors Terminals

Courtesy of © TOYOTA, LICENSE AGREEMENT TMS1002

NG: REPAIR OR REPLACE HARNESS AND CONNECTOR

OK: REPLACE RADIO AND PLAYER ECU

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.