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.
Code P026, Shorted Throttle Position Switch Circuit: Action
PCM turns on MIL, disables EGR and assumes throttle switch is closed if brakes are applied or if TP sensor position is less than or equal to 18 degrees. PCM also assumes open throttle when brakes are off or TP sensor position is greater than 18 degrees. Garage shift adapts are maintained at current levels.
- PCM input PI72 should cycle from LO to HI to LO when accelerator is depressed and released.
- If PCM input PI72 changes to HI when ISC motor is disconnected, fault is with ISC motor. If PI72 still stays LO, check circuit No. 427 for short to ground.
- Checks if circuit No. 427 is shorted to ground or if PCM is faulty.
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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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