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 Test SML - Switch Monitor Light
1) Check For Open SML Wire Turn ignition off. Install breakout box, leaving PCM disconnected. Measure resistance between SML test pin (No. 38) at breakout box and SML terminal at data link connector. See Figure . If resistance is less than 5 ohms, go to next step. If resistance is greater than 5 ohms, repair open SML wire.
2) Check For Short In SML Wire Turn ignition off. With breakout box installed and PCM disconnected, measure resistance between ground and SML test pin (No. 38) at breakout box. If resistance is 10,000 ohms or less, repair short in SML wire. If resistance is more than 10,000 ohms, check SML bulb, replace if necessary. If bulb is okay, replace PCM.
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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.