Need help with blinking lights. Lights set on auto. While driving, all lights, (dash, headlights, tail lights) flash on and off very quickly. Only does it for a few moments, (about a minute duration). During a 75 mile trip it happend probably 5 separate times. Engine showed no loss of power (by feel or rpm) during these times. Any thoughts?

 

Could be a grounding issue....

 

What's best starting point to troubleshoot that possible issue? Are there any other possibilities?

 

Given the nature of electronic faults in these cars, there are a number of possibilities....

I would start by removing, cleaning, and burnishing all battery cables, including the ground. I would also look for water in my trunk, specifically in the spare tire wheel well....

 

+1 and also have a hunt around in the trunk after taking out the spare to make sure there are no cables shorting out / loose (such as the transit one - if you can't find it then all's OK with it lol).

 

Does this fault occur on any other light-switch setting?

 

With the miles and age I would consider the MFS (Multi Function Switch). Yes us old guys call it the turn signal switch.

But it's just a guess since you have done no troubleshooting.
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Haven't had a chance to check on other settings. No water or detectable moisture in trunk. Battery connections and wires look good, clean and tight.

Did notice that headlights were ON in bright lighted conditions (daylight) while set on auto. Need to mention also that recently, (couple of weeks ago), battery drained low enough, after getting windows tinted, that car needed a boost to start. I did, however, get all the low voltage messages cleared throughout the system afterward. Have not put a good recharge on battery since.

 

That's likely your problem. May now be too late but worth a long (12+ hour) charge.

 

I think it may be related to the MFS as the sometimes headlights on bright go to dim on their own. How involved is diagnostic/repair?

 

It's not too hard to change the MFS but I am just guessing? Do you have the JTIS? I have not changed one on the S Type and the last one I did change was on a 1993 Ford. The one on the S Type is more complicated but looks like it's installed the same way.

Remove the plastic shroud around the steering column and you should be able to see what to unbolt.
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