1. Check the Hazard Light Switch:
* Visual Inspection: Examine the hazard light switch itself for any signs of damage, cracks, or loose connections. It's located on the center console. Try wiggling it gently while checking if the hazard lights or indicators flicker.
* Continuity Test (Advanced): If you have a multimeter, you can test the continuity of the switch in various positions (hazard on/off, left/right indicators). This requires knowledge of the switch's wiring diagram.
2. Inspect the Turn Signal Stalk:
* Visual Inspection: The turn signal stalk (the lever you use to activate the indicators) can wear out internally, causing intermittent or complete failure. Look for any obvious damage or loose connections at the stalk itself.
* Testing (Advanced): Again, a multimeter could be used to test the continuity of the stalk switch in different positions. This requires a wiring diagram.
3. Check the Wiring Harness:
* Visual Inspection: This is the most time-consuming step. Carefully inspect the wiring harness related to the turn signals and hazard lights. Look for:
* Broken wires: Look for any exposed wires, frayed insulation, or signs of rodent damage. Pay close attention to areas where wires bend or flex frequently.
* Corrosion: Check connectors for corrosion, especially those under the dash and near the car's body.
* Loose connections: Ensure all connectors are securely plugged in.
* Continuity Test (Advanced): With a wiring diagram, you can use a multimeter to trace the wiring from the switches to the indicator lamps, checking for continuity along the way.
4. Examine the Indicator Lamps Themselves:
* Bulb Check: Though you've checked the fuses, ensure all the indicator bulbs (front and rear) are working and correctly installed. A burned-out bulb can sometimes cause issues with the entire system.
5. Consider the Light Switch (Main):
* Test: While less likely, a faulty main light switch could interfere with the indicator circuits. Try other light functions to see if they are behaving normally.
6. Consult a Wiring Diagram:
A wiring diagram specific to your 1988 Mercedes 190E is crucial for effective troubleshooting. You can find these online through Mercedes forums or parts websites. The diagram will show you the exact path of the electrical signals, making it easier to pinpoint the fault.
7. Professional Help:
If you are not comfortable with electrical diagnostics or lack the necessary tools, it's best to take your car to a qualified mechanic specializing in Mercedes-Benz vehicles. They'll have the expertise, tools, and wiring diagrams to quickly diagnose and repair the problem.
Remember safety first! Disconnect the battery's negative terminal before working on any electrical components. Improper electrical work can be dangerous.
