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.
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HOMESERVICE MANUALSNISSAN-DATSUN1991240SX LE, STANDARDREPAIR AND DIAGNOSISENGINE PERFORMANCESYSTEMENGINE CONTROLS - BASIC TESTINGIGNITION CHECKSOPTICAL (300ZX)POWER TRANSISTOR CIRCUITS
1991 Nissan-Datsun 240SX LE, Standard
Power Transistor Circuits
1991 Nissan-Datsun 240SX LE, StandardSECTION Power Transistor Circuits
- Disconnect 7-pin connector from power transistor unit. Disconnect 3-wire ignition coil connector.
- Check continuity of each circuit between ignition coil connector terminal "C" and corresponding wire terminal of power transistor unit 7-pin connector. See Figure for ignition coil connector terminal identifications. For wire colors and related ECU connector terminals, see appropriate diagram in WIRING DIAGRAMS article. Repair as necessary.
- Disconnect power transistor unit 6-pin connector. Disconnect ECU connector. Check continuity of each wire circuit between power transistor unit and corresponding wire terminal of ECU connector. See appropriate diagram in WIRING DIAGRAMS article.
- If continuity does not exist in any of the power transistor 6-pin connector wire terminals, repair open circuit in wires. If there is continuity in all wires but one or more ignition coils is inoperative, reconnect all connectors. Go to ECU POWER TRANSISTOR OUTPUT SIGNAL test below.
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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.