Code 14 & 15 (CTS)

1988 Chevrolet Spectrum Base, 2D Hatchback, AutomaticSECTION Code 14 & 15 (CTS)
  1. Remove CTS connector and check voltage across harness terminals. Turn ignition on. If reading is below 4 volts, go to step 2). If reading is above 4 volts, connect an ohmmeter across CTS terminals. Read resistance on ohmmeter. See COOLANT TEMPERATURE SENSOR RESISTANCE  table. If resistance is not equal to table reading, replace CTS.
    COOLANT TEMPERATURE SENSOR RESISTANCE

    Temperature Ohms
    -22°F (-30°C) 26,000
    -4°F (-20°C) 15,000
    32°F (0°C) 5600
    68°F (20°C) 2500
    104°F (40°C) 1200
    140°F (60°C) 600
    176°F (80°C) 320
    212°F (100°C) 180
  2. Disconnect B connector at ECM. Using an ohmmeter, check that continuity exists in CTS harness B10 and Green/Black wire at CTS, and B18 and Blue/Green wire at CTS.
  3. Check that no continuity exists between B10 and B18, and between B10 and ground or B18 and ground.
  4. Using a voltmeter, check voltage in CTS harness Green/Black wire and ground. Reading should be 4-6 volts. If harness checks bad, repair or replace. If harness checks good, replace ECM.
RENDER: 1.0x

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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.