Q: How to check the Coolant Temperature Sensor for Chevrolet Astro?
A: To test the Temperature Warning Light System, ensure the light turns on when the Ignition is on. If not, check the bulb. If the light remains on with a cold engine, disconnect the wire at the sending unit. If the light goes off, replace the unit. If it stays on, the wire is grounded in the harness. For the Temperature Gauge System, check the fuse if the gauge doesn't work. If the fuse is fine, disconnect the wire from the sending unit and ground it. Turn on the ignition; if the gauge registers at maximum, replace the unit. If not, the gauge or wiring may be faulty. To replace the sending unit, cool the engine, remove the cover, disconnect the wire, and unscrew the unit. Install the new unit, connect the wire, and replace the cover.