1. Check the Obvious First:
* Fuel Level: Make absolutely sure the gas tank isn't actually empty. A surprisingly common cause of a non-working gauge is... no gas!
* Gauge Itself: Does the gauge work at all? Does the needle move at all, even slightly, when the ignition is turned on? If it's completely dead, the problem is likely with the gauge itself or its power supply.
* Fuse: Check the fuse related to the instrument cluster (your owner's manual will tell you which one). A blown fuse is an easy fix.
2. Testing the Wiring:
This involves using a multimeter. If you're not comfortable working with electricity, it's best to take it to a mechanic. Always disconnect the negative battery terminal before starting any electrical work.
* Locate the Fuel Level Sender: This is located in the gas tank. Accessing it usually requires dropping the fuel tank (a somewhat involved process).
* Understanding the Circuit: The fuel level sender is essentially a variable resistor. As the fuel level changes, the resistance changes, sending a signal to the instrument cluster. The circuit usually involves a ground wire, a power wire (usually 12V), and the signal wire from the sender.
* Testing the Power Wire: With the ignition on, test the power wire at the fuel level sender connector. You should read approximately 12V. If not, trace the wire back towards the fuse box, checking for breaks or poor connections along the way.
* Testing the Ground Wire: Check the ground wire at the fuel level sender connector. With the multimeter, test for a good ground connection (near 0 ohms resistance to a known good ground point on the chassis).
* Testing the Signal Wire: This is the trickiest part. You'll need to test the resistance of the signal wire. The resistance will vary depending on the fuel level. With an empty tank, the resistance will be high; with a full tank, it will be low. Consult a wiring diagram for your specific Malibu model to determine the expected resistance ranges. If the resistance is outside of the expected range or doesn't change with fuel level, the sender unit itself might be faulty. You'll also need to test continuity (infinite resistance would mean a break in the wire).
3. More Advanced Troubleshooting:
* Wiring Diagram: Obtain a wiring diagram for your 1999 Chevy Malibu. This will show you the exact path of the wires from the sender to the gauge. You can usually find these online, through repair manuals, or at a parts store.
* Instrument Cluster Test: If the wiring to the sender checks out, the problem could be in the instrument cluster itself. Testing this requires more advanced knowledge and tools.
* Professional Help: If you're not comfortable with electrical work or can't find the fault, take your Malibu to a qualified mechanic. They have the tools and expertise to diagnose the issue accurately.
Important Safety Note: Gasoline is highly flammable. Take extreme caution when working near the fuel tank. Ensure proper ventilation and avoid sparks or open flames. If you're unsure about any step, consult a professional mechanic.
