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
PCM is powered by 5 power feeds. Two of these feed are from the battery, the other 3 are from the ignition switch and are called Ignition 1, Ignition 0 and Ignition Supplement. The ignition feeds are powered any time the key is in the CRANK, RUN or ACC positions. This test is used to monitor the voltages received by the PCM at PCM harness connector terminals No. 18 and 19.
When engine is running, PCM will compare the Ignition 1 voltage it receives at terminal No. 19 to the Ignition 0 voltage it receives at terminal No. 18. If voltage difference is greater than 2 volts for 5 seconds, DTC will set.
NO RELATED
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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.