Astro & Safari
- If gauge reads "COLD" when engine is hot, go to next step. If gauge reads "HOT" when engine is cold, go to step 5). If gauge readings are too low, go to step 7). If gauge readings are too high, go to step 8).
- Check for blown fuse and replace if necessary. If fuse is okay, disconnect lead from sending unit and turn ignition on. Connect a test light between lead and ground. If test light glows, go to next step. If not, go to step 4).
- Connect lead to a known good ground. If temperature gauge reads "HOT", check lead connector on sending unit. If okay, replace sending unit. If gauge still reads "COLD", replace temperature gauge.
- If test light did not glow, check continuity between sending unit terminal at gauge and ground, and between ignition terminal and ground. Also check temperature gauge case ground. If all checks are okay, replace temperature gauge.
- If gauge constantly reads "HOT", remove lead from temperature gauge sending unit. Gauge reading should go to "COLD". If gauge reading does not swing to "COLD", check sending unit for an external short. If there is no external short, replace sending unit.
- If temperature gauge continues to read "HOT" after replacing sending unit, check for short circuit in wiring between sending unit and gauge. If no short exists, replace temperature gauge.
- If readings are inaccurate, check wiring for corroded or loose connections. If necessary, clean and tighten terminals and connections. Also check resistance in temperature sending unit ground circuit. If terminals connections and ground circuit are okay, go to next step.
- Disconnect lead from temperature gauge sending unit. Using an ohmmeter, test sending unit resistance. See TEMPERATURE GAUGE SENDING UNIT RESISTANCE table. If sending unit values are incorrect, replace temperature gauge sending unit.
TEMPERATURE GAUGE SENDING UNIT RESISTANCE
| Degrees °F (°C) | Ohms |
|---|---|
| 104 (40) | 1365 |
| 257 (125) | 55 |