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.
1998 Infiniti Q45 BaseFACTORY OEM SERVICE PROCEDURE
Ground Circuits (Q45)
- Using a DVOM, measure resistance between ground and PCM terminals No. 121, 122, 125, 126, 127and 128 by backprobing. See Figure . Resistance should be zero ohms at all terminals. If resistance is as specified, go to next step. If resistance is not as specified, repair open or poor connection in appropriate circuit.
- Using a DVOM, connect negative lead of DVOM to a good ground. Using positive lead of DVOM, backprobe at PCM terminals No. 121, 122, 125, 126, 127 and 128. With vehicle running, DVOM should indicate less than one volt at all terminals. If voltage is as specified, ground circuits are okay at this time. If voltage is not as specified, repair short to voltage in appropriate circuit.
Factory Service Tools
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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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