headlights, control lights pulsing

[Maeven]

I have a 1998 ford taurus. the control lights and headlights are rapidly pulsing dim to normal. I have checked relays and fuses, (i am pretty sure I did not miss any) and all seem to be in working order. Does anyone have any ideas of what this could be or where to trouble shoot from here?

[shorod]

Welcome to the forum!

What do you mean by "control lights?" Are you referring to the instrumentation lights and switch backlighting? Since the headlights are pulsing too, that seems like an issue with the charging system such as a loose battery cable or maybe an alternator that's on it's way out.

-Rod

[Maeven]

Thank you for taking the time to respond to my question. By control lights, I mean what my boyfriend refers to as the "idiot lights", such as the little buckle your seat belt guy and what not near the gauges. They pulse in rhythm with the main headlights. I took the fuse out of the day running lights because they annoyed me, but other than that I have made no changes. The car is older and has been a pretty good car. I just have hit a wall in this latest lighting issue.

[shorod]

Ahhh, if you would have typed "idiot lights" I would have known exactly what you were referring to.

So, I think what you're saying is that the headlights flicker while driving, and at the same time the headlights flicker, the "idiot lights" also flicker. And, during normal driving, the idiot lights are not illluminated. Whatever's causing the headlights to flicker would also seem to be causing the idiot lights to momentarily illuminate?

If that's accurate, my first suggestion is still to check out the charging system, verifying first that the battery cables are clean and tight. Also, make sure your car has OEM molded battery cables. If one or both of the cables is the "temporary" type that clamps on to the cable, get rid of it and replace that cable assembly with a molded style. Those temporary clamps allow corrosion to occur in the cable and can contribute to all sorts of issues.

If the cables are the molded style, removing the clamps from the battery reveals clean connections, and everything is clean and tight, I'd then suggest making sure the alternator is working well. Do you have a way to monitor the system voltage while the lights act up? Such as connecting a voltmeter to the cigarette light or similar? If so, try that while driving the car and see if the system voltage fluctuates at the same time as the headlights. If it does, then you might consider replacing the alternator once you verify the belt is good and connections at the alternator are clean and tight.

If the system voltage does not fluctuate with the lights flickering, then you should inspect grounds for the system. There are not a lot of grounds that are common to the headlights, PCM, and instrument panel though....

Also, there are a fair number of strange electrical gremlins that have been associated with the Digital Transmission Range Sensor (DTRS/TRS - aka: park/neutral safety switch). I don't recall anyone reporting issues similar to what you describe, but it's not to say that it couldn't happen.

-Rod