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.
Inspection Procedure
- Check voltage between terminals + B and E1 of ECM connectors.
PREPARATION:
- Remove the ECM hood (see ENGINE CONTROL MODULE (ECM) ).
- Turn the ignition switch ON.
CHECK:
Measure the voltage between terminals +B and E1 of the ECM connectors.
Courtesy of © TOYOTA, LICENSE AGREEMENT TMS1002
OK:
- Voltage: 9 to 14 V
OK: Proceed to next circuit inspection shown on problem symptoms table (See PROBLEM SYMPTOMS TABLE ).
NG: Go to next step.
- Check for open in harness and connector between terminal E1 of ECM connector and body ground (See HOW TO USE THE DIAGNOSTIC CHART AND INSPECTION PROCEDURE
).
NG: Repair or replace harness or connector.
OK: Go to next step.
- Check voltage between terminal IGSW of ECM connector and body ground.
PREPARATION:
- Remove the ECM hood (see ENGINE CONTROL MODULE (ECM) ).
- Turn the ignition switch ON.
CHECK:
Measure the voltage between terminal IGSW of the ECM connector and the body ground.
OK:
- Voltage: 9 to 14 V
OK: Go to step 6 .
NG: Go to next step.
- Check IGN fuse.
PREPARATION:
Remove the IGN fuse from the passenger side J/B.
CHECK:
Check the IGN fuse resistance.
OK:
- Resistance: Below 1 Ω
NG: Check for short in all harness and components connected to IGN fuse.
OK: Go to next step.
- Check ignition switch (See INSPECTION
).
NG: Replace ignition switch.
OK: Check and repair harness and connector between battery and ignition switch, and ignition switch and ECM.
- Check voltage between terminal MREL of ECM connector and body ground.
PREPARATION:
- Remove the ECM hood (see ENGINE CONTROL MODULE (ECM) ).
- Turn the ignition switch ON.
CHECK:
Measure the voltage between terminal MREL of the ECM connector and the body ground.
OK:
- Voltage: 9 to 14 V
NG: Replace ECM (See ENGINE CONTROL MODULE (ECM) ).
OK: Go to next step.
- Check EFI fuse of engine room No. 1 R/B.
PREPARATION:
Remove the EFI fuse from the engine room No. 1 R/B.
CHECK:
Check the EFI fuse resistance.
OK:
- Resistance: Below 1 Ω
NG: Check for short in all harness and components connected to EFI fuse.
OK: Go to next step.
- Check EFI main relay (Marking: EFI) (See EFI MAIN RELAY
).
NG: Replace EFI main relay.
OK: Go to next step.
- Check for open and short in harness and connector between terminal MREL of ECM and body ground (See HOW TO USE THE DIAGNOSTIC CHART AND INSPECTION PROCEDURE
).
NG: Repair and replace harness or connector.
OK: Check and repair harness or connector between EFI fuse and battery.
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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.
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