1. Check the Bulbs:
* Obvious, but essential: Make sure all your turn signal bulbs are good. A burned-out bulb in one location can sometimes prevent the entire system from functioning correctly due to the way the system is wired (this is common in older cars). Check both front and rear bulbs.
2. Inspect the Flasher Unit:
* Location: The flasher unit is a small, usually rectangular, electronic component. Its location varies by year and model, but common spots are under the dash, near the steering column, or in the fuse box. Consult your owner's manual or a wiring diagram to locate it.
* Testing: The simplest test is to replace it. They're inexpensive. If replacing it fixes the issue, great! If not, continue troubleshooting. (Note: Some older flashers are mechanical; these are less common now and a replacement will almost certainly be electronic.)
3. Examine the Turn Signal Switch:
* Difficult to test directly: This is often the culprit. Testing this requires either a wiring diagram and a multimeter, or professional diagnostics. The switch is located on the steering column. A faulty switch may be intermittently working, explaining why sometimes it works and sometimes it doesn't. Replacement is often the best solution if suspected.
4. Investigate Wiring and Connections:
* Look for broken wires: Carefully inspect the wiring harness connected to the turn signal switch, flasher unit, and bulbs. Look for any broken, frayed, or corroded wires. Pay close attention to connections – loose or corroded connectors are a common source of intermittent electrical problems. A visual inspection is often insufficient; you may need to use a multimeter to check continuity.
* Grounding issues: Poor grounding is another potential problem. Ensure that the car's chassis provides a good ground for the turn signal system. Clean any ground connections you find.
5. Multi-meter Testing (Advanced):
* Wiring Diagram: You'll absolutely need a wiring diagram specific to your '78 Chevy Malibu. You can often find these online through forums dedicated to classic Chevy vehicles.
* Continuity Test: With the diagram, use a multimeter to test the continuity of the wires in the turn signal circuit. This involves checking whether there's an unbroken electrical path between various points in the circuit.
* Voltage Test: Check for voltage at the switch, flasher, and bulbs when the turn signals are activated. This helps pinpoint where the signal is lost.
6. Seek Professional Help:
If you're not comfortable working with car electronics or if the problem persists after these steps, it's best to take your car to a qualified mechanic specializing in older vehicles. They have the experience and tools to diagnose and repair more complex electrical issues.
Remember safety first! Disconnect the negative battery terminal before working on any electrical components in your car. Always refer to a wiring diagram for your specific vehicle model and year before attempting any repairs.
