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 MANUALSTOYOTA2000TACOMA BASE, 2D PICKUP, 2.4 L, STANDARDREPAIR AND DIAGNOSIS (SINGLE PAGE)ENGINE PERFORMANCETESTING & DIAGNOSISENGINE CONTROLS - SYSTEM & COMPONENT TESTING - 4-CYLINDERCOMPUTERIZED ENGINE CONTROLSENGINE CONTROL MODULE (ECM) POWER SOURCE CIRCUITECHO
2000 Toyota Tacoma Base, 2D Pickup, 2.4 L, Standard
Engine Control Module (ECM) Power Source Circuit: Echo
2000 Toyota Tacoma Base, 2D Pickup, 2.4 L, StandardSECTION Echo
- Remove cover from ECM for access to ECM electrical connectors. ECM is located behind glove box. For illustration of ECM location, see THEORY & OPERATION article. Note ECM electrical connector terminals. See Figure.
- Turn ignition on. Using voltmeter, check voltage between terminals No. 12 (Black/Red wire) at ECM electrical connector E4 and No. 14 (Brown wire) at ECM electrical connector E7. This is the +B and E1 terminals at ECM. Voltage should be 9-14 volts. If voltage is within specification, diagnose by symptom. See TROUBLE SHOOTING - NO CODES article. If voltage is not within specification, check for open in wiring harness and electrical connectors between terminal No. 14 (Brown wire) at ECM electrical connector E7 and body ground. If wiring harness and electrical connectors are okay, go to next step. If wiring harness or electrical connector is defective, repair as necessary.
- Check operation of EFI main relay. See EFI MAIN RELAY under RELAYS. If EFI main relay operates properly, go to next step. If EFI main relay is defective, replace EFI main relay.
- Check for defective EFI fuse. EFI fuse is located in fuse/relay box at driver-side front corner of engine compartment, just in front of strut tower, near battery. If EFI fuse is okay, go to next step. If EFI fuse is defective, repair short in wiring harness and components connected to EFI fuse. See WIRING DIAGRAMS article.
- Check for open in wiring harness and electrical connectors between EFI main relay and battery, and between EFI main relay and ECM. See WIRING DIAGRAMS article. If wiring harness and electrical connectors are okay, go to next step. If wiring harness or electrical connector is defective, repair as necessary.
- Check ignition switch. See appropriate STEERING COLUMN SWITCHES article in ACCESSORIES & EQUIPMENT. If ignition switch is okay, go to next step. If ignition switch is defective, replace ignition switch.
- Check for open in wiring harness and electrical connectors between ignition switch and EFI main relay, and between body ground and EFI main relay. See WIRING DIAGRAMS article. If wiring harness and electrical connectors are okay, test is complete. If wiring harness or electrical connector is defective, repair 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:
- • 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.