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 STO - Self-Test Output
| Circuit | Breakout Box Pin No. | PCM Pin | Wire Color |
|---|---|---|---|
| STO | 17 | 1F | White/Black |
1) Check System Integrity Visually check all wiring and connectors for evidence of damage, shorting or looseness. If a fault is found, repair as necessary. If no fault is found, go to next step.
2) Check For Open STO Wire Turn ignition off. Install breakout box, leaving PCM disconnected. Measure resistance between STO test pin at breakout box and PCM STO terminal at Data Link Connector (DLC). See Figure . If resistance is less than 5 ohms, go to next step. If resistance is at least 5 ohms, repair open PCM STO wire.
3) Check For Short In STO Wire Ensure ignition is off, breakout box is installed and PCM disconnected. Measure resistance between ground and STO test pin at breakout box. If resistance is more than 10,000 ohms, go to CIRCUIT TEST PGC. If resistance is 10,000 ohms or less, repair short to ground in PCM STO wire.
NO RELATED
Use the Manual With the Right Hardware
Pair factory procedures with proven DIY tools so the instructions are easier to execute.
Affiliate disclosure: We may earn a commission at no extra cost to you.
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.