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 MANUALSTOYOTA2013TUNDRA BASE, 5.7L ENG VIN WREPAIR AND DIAGNOSISBODY & FRAMEDOOR LOCKSENGINE IMMOBILISER SYSTEM (DIAGNOSTIC CODES & CIRCUIT TESTS)ENGINE IMMOBILIZER SYSTEMCIRCUIT TESTSECU POWER SOURCE CIRCUITPROCEDURE
2013 Toyota Tundra Base, 5.7L Eng VIN W
ECU Power Source Circuit: Procedure
2013 Toyota Tundra Base, 5.7L Eng VIN WSECTION Procedure
- INSPECT FUSE (IMB, IGN)
- Remove the IMB fuse and IGN fuse from the engine room relay block.
- Measure the resistance according to the value(s) in the table below.
Standard resistance
Tester Connection Condition Specified Condition IMB fuse Always Below 1 Ω IGN fuse
NG → REPLACE FUSE
OK: Go to next step
- CHECK HARNESS AND CONNECTOR (TRANSPONDER KEY ECU - BATTERY AND BODY GROUND)
- Disconnect the J26 ECU connector.
- Measure the resistance and voltage according to the value(s) in the table below.
Standard resistance
Standard voltage
Tester Connection Condition Specified Condition J26-16 (GND) - Body ground Always Below 1 Ω Tester Connection Switch Condition Specified Condition J26-1 (+B) - Body ground Always 11 to 14 V J26-2 (IG) - Body ground Ignition switch OFF Below 1 V Ignition switch ON 11 to 14 V
NG → REPAIR OR REPLACE HARNESS OR CONNECTOR
OK → See step 3
- PROCEED TO NEXT CIRCUIT INSPECTION SHOWN IN PROBLEM SYMPTOMS TABLE. Refer to 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.