Originally posted here: http://www.focusfanatics.com/forum/showpost.php?p=6887265&postcount=13
Originally Posted by InfraredZTW View Post
Car runs great now.
The only thing i noticed is:
- upon a COLD START only - all lights will go from dim to bright about 3 times, then the smart charge kicks in (as shown by the handy batt/alternator tester plugged in the cig. lighter) and slowly comes up to perfect alternator voltage output
- on HOT START - car starts perfectly with no light flicker
- after engine heats up, if i turn accessories on (ac, defrost, etc) the alt voltage drops and stays down at idle.
My car is having pretty much the same issues. More info:
- Problem was first noticed about a week ago.
- On a cold start (cold is not cold outside - maybe 60-65 ambient Fahrenheit), when first driving (night, headlights, HVAC Defrost, Rear Window Defrost On), lights will alternately dim down heavily. Most noticeable with the instrument cluster lights, but you can tell the headlights and HVAC lights are dimming also.
- This is not a mild dimming issue - cluster goes from bright to almost unreadable, lights are obviously much dimmer than normal. (I don't keep the dash lights super-bright, but I would estimate the lights with the dimming are not as bright as they would be with the engine off and only the battery powering them.)
- There doesn't seem to be a pattern to the dimming. Lights DO NOT vary with RPM. I've seen the lights go dim as the RPM is increasing and vice versa. No real time pattern either - sometimes they will dim for 2-5 seconds and then be normal before repeating, sometimes for only a 1/2-second or so.
- Once the engine reaches normal operating temperature (190-200 degrees) (3-5 miles of driving), the problem goes away and won't happen again until the next morning (that I know of - I don't usually drive at night.)
- Car is a 2002 Ford Focus SE Comfort ZETEC Automatic Sedan with 143K miles. (It's blue.)
- Alternator was replaced 4-months ago. Autozone alternator replacing defective older Autozone alternator.
- Battery is Autozone 40R-72, 30 months old, 24-months free replacement, 72-months pro-rate.
- Yesterday evening, I checked battery terminals: tight, cleaned off minor corrosion; and fluid level (at bottom of split ring but above plates, added a slight bit of water to bring level to top of split rings), battery surface voltage was 12.71 to 12.35 - but this was warm temp after driving the car home. No real change in the morning - duration of dimming might be slightly less, but still occurred. Did not check alternator connections.
- During the day with a DMM - readings are normal (i.e. 12.65 surface volts, 12.3 volts after lights on for 30 seconds without engine running, 14.1 volts with engine running and lights and defrost on).
- About a month ago, I replaced the dome, trunk, HMSL, and license plate bulbs with LEDs. Likely unrelated, but that is the most recent semi-major change to the car.
- I added heavier ground wires years ago between the engine and the fender and the battery negative and the fender.
- The battery could be going out, it's about time (just after the free replacement period), but the post above said a new battery made the issue worse, so ...
- I suppose something could be drawing the battery down overnight so that it still had enough juice to start the car, but was loading down the alternator - but I would expect the dimming to vary with RPM, then.
- Possibly something with the new alternator - It is lifetime parts warranty and I think still within the labor warranty (a shop changed it, it died away from home four months ago).
- Possible voltage regulator (which means new alternator).
- Possibly bad ground points, but I'm not sure how to check these.
- Possible wiring connection issues - I've read of Focus's having problems with the alternator connector plugs, but I'm not sure what I should be looking for.
I am considering having AutoZone run a free "cart test" on the alternator, but not sure this would find the issue if it is wiring and since it is intermittent and only with the engine cold.
I don't have an easy way to test the voltage output while driving - I have an Ultraguage, but it is the older model and doesn't read battery voltage on the Focus - http://www.amazon.com/INNOVA-3721-Battery-Charging-Monitor/dp/B000EVWDU0/ref=cm_cr_pr_sims_t
would work - but I hate spending $14 to find out the voltage is dropping in the morning, which I can already tell.
Thanks in advance for suggestions!!!