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.
Circuit Description
The ignition relay is a normally open relay. The relay armature is held in open position by spring tension. When ignition switch is turned to run or start position, current will flow through relay coil. A wire connected to other end of relay coil completes path to ground. The electromagnetic field created by relay coil, overcomes spring tension and moves armature allowing relay contacts to close. The closed relay contacts allow current to flow from battery to following fuses: PCM 1, ETC/ECM, INJ 1, INJ 2 and SBA fuse, if equipped.
When ignition switch is turned off, electromagnetic field collapses. This action allows spring tension to move armature away from relay contacts, which interrupts current flow to fuses. If ignition relay fails to close, engine will crank, but will not run. The class 2 communications will be available with use of a scan tool.
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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.