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Coolant Temperature Gauge

  1. If coolant temperature gauge indicates hot, with engine cool and ignition switch in "RUN" position, proceed to step 3). If coolant temperature gauge indicates cold at all times, proceed to step 4). If coolant temperature gauge is inaccurate, proceed to step 6).
  2. If coolant temperature indicator light illuminates when engine coolant is not overheated, proceed to step 8). If coolant temperature indicator does not light when engine coolant is overheated, proceed to step 9).
  3. Turn ignition switch to the "RUN" position, disconnect coolant temperature sending unit. If gauge reads cold, replace coolant temperature sending unit. If gauge does not read cold, check instrument cluster printed circuit for short to ground. Check Light Green and Dark Green/Yellow wires for short to ground. If okay, replace coolant temperature gauge.
  4. With ignition switch in "RUN" position and coolant temperature sending unit disconnected, install jumper wire between Dark Green/Yellow and ground.
  5. If gauge reads hot, replace coolant temperature sender switch. If gauge reads cold, check the Light Green and Dark Green/Yellow wires, printed circuit and gauge connections for an open circuit. If okay, replace coolant temperature gauge.
  6. With coolant temperature sending unit disconnected, install Tester (J-33431) between harness connector Dark Green/Yellow wire and ground. Set resistance value to 1400 ohms and then to 55 ohms. Gauge should read cold then hot.
  7. If gauge responds correctly, and the wiring and gauge are okay, replace coolant temperature sending unit. If gauge does not respond correctly, check gauge connections and Dark Green/Yellow wire for high resistance. If both okay, replace coolant temperature gauge.
  8. Turn ignition switch to "RUN" position and disconnect coolant temperature sending unit. If indicator stays on, check Dark Green wire for short to ground. If indicator goes out replace coolant temperature sending unit.
  9. Turn ignition switch to "RUN" and disconnect coolant temperature sending unit. Install a fused jumper wire between Dark Green wire and ground. If coolant temperature indicator comes on, replace coolant temperature sending unit. If not, check Dark Green wire and instrument cluster printed circuit for an open circuit.
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