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 20 (ENGINE CONTROL SYSTEM SELF-DIAGNOSTICS - V6)DIAGNOSTIC TESTSDTC P1600: ENGINE CONTROL MODULE BATT CIRCUITDIAGNOSIS & REPAIR
2004 Toyota Matrix XR, FWD, Standard
Diagnosis & Repair
2004 Toyota Matrix XR, FWD, StandardSECTION Diagnosis & Repair
WARNING: This page is about a different car, the 2002 Toyota Tundra. However, it is still accessible from the selected car via links, so may be relevant.
- Remove glove box and heater duct (if necessary) for access to ECM with electrical connectors still installed on ECM. See Figure. Using voltmeter, check voltage between body ground and terminal No. 1 (Black/Red wire) at ECM electrical connector E3. See Figure. This is the BATT terminal on ECM. Voltage should be 9-14 volts. If voltage is not within specification, go to next step. If voltage is within specification, replace ECM.
- Remove EFI No. 1 fuse (15-amp) from fuse/relay box at driver's side front corner of engine compartment. Inspect EFI No. 1 fuse. If EFI No. 1 fuse is okay, reinstall fuse. Check wiring harness and electrical connectors between EFI No. 1 fuse and ECM. See WIRING DIAGRAMS article. It may be necessary to check wiring between battery and EFI No. 1 fuse. For additional wiring for EFI No. 1 fuse to the battery, see POWER DISTRIBUTION article in WIRING DIAGRAMS. If EFI No. 1 fuse is defective, replace fuse and check for short in wiring harness and components connected to EFI No. 1 fuse. See WIRING DIAGRAMS article. Repair wiring harness or electrical connectors as necessary.
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When to See a Mechanic
Stop DIY work and contact a certified mechanic immediately if any of the following apply:
- β’ You smell fuel, burning insulation, or see smoke.
- β’ Brakes feel soft, pull hard to one side, or make grinding noises.
- β’ The engine overheats, stalls repeatedly, or misfires under load.
- β’ You are missing required tools, torque specs, or safe lifting equipment.
- β’ You are not confident in the next step or safety outcome.