Since I started driving this car, I've experienced an intermittent problem that somehow involves the headlights, turn signals and engine ignition.

1) The headlights won't go to high beams. I just replaced the headlight relay, thinking it was bad, but no high beams still.

2) When I turn on the headlights, sometimes, not all the time, the engine misfires and runs very rough. If I turn the headlights off and leave the parking lights on, no misfire.

3) The turn signals are erratic. They will flash at different rates. Last night I pulled over in a parking lot because the car was running so rough. I left the right turn signal on for a minute and it stared flashing faster and faster, until it was almost a strobe light. I could hear a relay on the fuse block buzzing because it was working so fast.

What is happening here???

Sounds like a loose or oxidized ground or power connection somewhere.

Get your voltmeter (if you don't have one, buy one) and when this issue is happening, lights/turnsignals on, engine on, measure different voltage points around the vehicle including:

1) Battery POS voltage on terminal and terminal clamp to chassis ground (not negative terminal) (checks POS battery connection: both should read >12.6V during lights on/engine running)

2) Battery NEG voltage on terminal and terminal clamp to chassis ground (checks neg battery connection: both should be 0 V)

3) Engine Coil POS terminal to chassis ground. (Should read >12.6V)

4) Engine block to chassis ground (Checking engine grounding; should be 0 V)

5) Voltage at proper turn signal and headlight fuses to chassis ground. (Should be >12.6V)

Check ground straps from battery to chassis.
Check ground straps from tranny to trunk floor.
If loose or corroded, clean and tighten, replace if corroded.

There is also a POS terminal lug on the inside wheel well behind the fuse panel in the interior. This POS distribution lug should be tightened. DISCONNECT battery NEG terminal FIRST before dropping fuse panel and tightening POS terminal lug.

Spoke

Thanks, Spoke. I'll check all those things. I suspect it may be corrosion somewhere, maybe on the fuse block.

Is there any way to test those black round relays to see if they're working properly?