2001 Infiniti Q45 BaseFACTORY OEM SERVICE PROCEDURE

Ignition Signal: G20

  1. Attempt to start engine. If engine does not start, go to next step. If engine starts, let it idle. Using an oscilloscope, measure voltage between ground and ECM terminal No. 36 (Green wire) by backprobing. See Figure and Figure . Waveform should match waveform shown in chart. See PIN VOLTAGE CHARTS article. If waveform is as specified, system is okay. If waveform is not as specified, go to step  8.
  2. Turn ignition off. Disconnect distributor 2-pin harness connector (for ignition coil). Turn ignition on. Measure voltage between ground and distributor 2-pin harness connector terminal No. 8 (Green/White wire). If battery voltage exists, go to next step. If battery voltage does not exist, repair open or short circuit and retest system. See WIRING DIAGRAMS article.
  3. Turn ignition off. Disconnect distributor 6-pin harness connector (for power transistor and CMP sensor). Check continuity between engine ground and distributor 6-pin harness connector terminal No. 5 (Black wire). See Fig 1. Also check circuit for short to voltage. See WIRING DIAGRAMS article. Repair circuit as necessary and retest system. If ground circuit is okay, go to next step.
  4. Disconnect ECM harness connector. See Figure. Check continuity of White/Black wire between distributor 6-pin harness connector terminal No. 6 and ECM harness connector terminal No. 35. See Figure. Also check circuit for short to ground and short to voltage. Repair circuit as necessary and retest system. If circuit is okay, go to next step.
  5. Measure resistance between distributor 2-pin connector terminals. Also measure resistance between ignition coil tower and distributor 2-pin connector terminal No. 8. See Fig 2. See IGNITION COIL RESISTANCE  table. If resistance is as specified, go to next step. If resistance is not as specified, replace distributor assembly and retest system.
  6. To check power transistor, measure resistance between distributor 6-pin connector terminal No. 5 (component side) and distributor 2-pin connector terminal No. 7 (component side). If resistance is zero ohms, replace distributor assembly and retest system. If resistance is not zero ohms, go to next step.
  7. Remove distributor cap. Measure resistance of resistor as shown in illustration. See Fig 3. Resistance should be 4000-8000 ohms at 77°F (25°C). If resistance is as specified, go to next step. If resistance is not as specified, replace distributor cap and retest system.
  8. Turn ignition off. Disconnect distributor 2-pin harness connector. Disconnect ECM harness connector. See Figure. Check continuity of Green wire between distributor 2-pin harness connector terminal No. 7 and ECM harness connector terminal No. 36. See Figure. Also check circuit for short to ground and short to voltage. Repair circuit as necessary and retest system. If circuit is okay, go to next step.
  9. No problem is indicated at this time. Problem may be intermittent. See INTERMITTENTS in TROUBLE SHOOTING - NO CODES article.
IGNITION COIL RESISTANCE

Application Resistance @ 77°F (25°C)
Primary (1) About 0.8 Ohm
Secondary (2) About 16K/Ohms
(1) Measured between distributor 2-pin connector terminals.
(2) See Fig 2.
Fig 1: Identifying Distributor 6-Pin Connector Terminals (G20)
G00010140Courtesy of NISSAN MOTOR CO., U.S.A.
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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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