[designo614]

Posting this as I try to troubleshoot my son's 2005 Focus. I don't drive it often, but the issue it has now is that, right around 40 mph and up the high beam switch will start to go on/off by itself very rapidly; you can see the dash light go on/off in rhythm with the switch clicking under the dash (or maybe its in the column?).

When this happens, the car loses power as in hesitates / cuts out, the radio turns off then back on with the clicking, the accelerator pedal will not respond.
This was intermittent, but now it is happening on every trip.

Any ideas? Should I start by replacing the switch, or is it perhaps the switch is getting bad information from somewhere else, like a relay...?

Thanks in advance-

 

[Marde]

My first guess is; cables and connections at and around the battery. Disconnect inspect clean bat terminals and lugs. Same for the black cable that goes down and connects onto the frame/chassis at drivers side wheel well; at this same spot are 1 or 2 other smaller electrical ground terminal lugs, disconnect and clean-up those too. Same spot but on passenger side is another one to clean-up.

 

[Marde]

I bought 2 generic battery cables at a car part store; less than $20 for both. Then I added these onto my car:

1) Bat neg <-to-> frame

2) Frame <-to-> engine

Ever since, mpg is way up; tires never go flat; fully stealth to police radar. But morphing is broken so it always looks like a Focus wagon. Very happy with my ground cable mod tho.

 

[sailor]

^^^ Yup, your light flashing sounds more like another symptom than the cause.

The multiple connections at the battery are a common problem area to always check first, and oddly the umbilical of wiring to the hatch/trunk is another. Flexing wires there loose insulation/break & cause short circuits that are intermittent for many odd behaviors.

 

[designo614]

Repaired... perhaps for now

Thanks for the input! I looked at the battery connections, and while the actual clamp to battery connections were fine, the cable to clamp connections in fact were somewhat corroded. So, I did the old baking soda paste trick on everything, further cleaned everything with emery paper and greased them up and re-assembled.

Test drove down the highway and the problem has resolved for now. If it returns, I am guessing the next step will be replacing the cables themselves. Perhaps should just go ahead and do it anyway for the minimal cost.

Thanks again for the input on this; I wasn't sure it this would have been a Focus specific problem or not.