1998 Infiniti QX4FACTORY OEM SERVICE PROCEDURE

Without Scan Tool (Except Quest)

  1. If use of an OBD-II type scan tool is not available, DTCs can be retrieved by changing PCM output from Mode 1 to Mode 2. Mode 1 is the normal malfunction warning mode. Mode 2 displays self-diagnostic results.
  2. To switch PCM output from Mode 1 to Mode 2, locate and gain access to PCM. See PCM LOCATIONS  table. Turn ignition on. Using a screwdriver, turn test mode selector fully clockwise. See Figure. After 2 seconds, turn test mode selector fully counterclockwise (back to original position). PCM should now be in Mode 2. When in Mode 2 with key on and engine off, MIL should begin flashing codes.
    PCM LOCATIONS

    Application Location
    Altima, Sentra, 200SX Under Dash, Behind Center Console
    Maxima Behind Glove Box
    Pathfinder, QX4 & Frontier Under Passenger Seat
    Quest Behind Glove Box
    240SX At Kick Panel Under Right Side Of Dash
  3. The 4-digit DTCs (flash codes) are read as two 2-digit numbers. The first 2-digit number is indicated by a series of long flashes followed by a series of short flashes. For example: one long flash followed by 2 short flashes indicates DTC 0102. See Figure. The DTCs retrieved by MIL are not numerically the same as DTCs retrieved from a scan tool. See appropriate DTC IDENTIFICATION table under SUMMARY .
  4. Write down codes and repair in order of priority. See DTC PRIORITY IDENTIFICATION  table. To determine which circuit test to use, see appropriate DTC IDENTIFICATION table under DIAGNOSTIC TROUBLE CODE DEFINITIONS . After retrieving DTCs or performing a repair, clear DTCs from PCM memory. See CLEARING CODES . If no DTCs or DTC P0000/MIL 0505 (pass code) were retrieved and fault still exists, proceed to TESTS W/O CODES article for diagnosis by symptom.
Factory Service Tools

Use the Manual With the Right Hardware

Pair factory procedures with proven DIY tools so the instructions are easier to execute.

Disclosure: Verified tool recommendations may earn an affiliate commission at no cost to you.

Shop Manual-Ready ToolsCompare Repair QuoteQuote Shield Pro

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.