Battery light flickering
- Thread starter TropicMustang
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wmburns
SN Certified Technician
belp slip
Nice sig. What year?
Assuming that the alternator has been tested and is good, look for evidence of belt slip (black power around the pulley). Are all of the idler pulleys in place?
Also, check fuse F1.5 (15a) in the Central junction box (CJB).
Check the small wiring connector to the alternator. Plugged in good? Clean?
Nice sig. What year?
Assuming that the alternator has been tested and is good, look for evidence of belt slip (black power around the pulley). Are all of the idler pulleys in place?
Also, check fuse F1.5 (15a) in the Central junction box (CJB).
Check the small wiring connector to the alternator. Plugged in good? Clean?
ChillPhatCat
Dirt-Old 20+Year Member
I'd say alternator is just starting to wear out... when it's really cold out, your battery tends to drain faster and probably puts a little more strain on the alternator right after you first start it up. I'd say it's unlikely to be belt slip because cold causes things to contract, not expand... so it should be tighter and be less likely to slip when you first start the car on a cold day.
wmburns
SN Certified Technician
The truth of the matter is that it could be a weak alternator, weak battery, or belt slip. IMO it is more likely to be a bad alternator. Which is why the 1st suggestion was to test the alternator.
As RPM's increase, more power is needed to run the engine's electronics. If the alternator is boarder line, the extra power requirements could push it over the edge.
Reminder, the battery light is driven off of battery voltage only. Further, the PCM reduces charging current at WOT (to save load on the motor). Consider if the battery is weak or the terminals are dirty, when the alternator output is decreased by design, the extra power has to be made up by the battery. This could overwhelm the battery's ability to keep up.
That is why it is also good idea to check/clean the battery terminals at the same time. Ensure that the top of the battery is clean as well. Todays car will not run without a solid battery.
Belt slip should be evident on the belt and around the pulleys. But, IMO, what makes the most sense is to TEST the alternator first. Almost any auto parts store will test your alternator for free. Many will do a basic function test with the alternator still on the car.
While the alternator is off, INSPECT the belt looking for evidence of slipping/cracking/wear. If found, replace it. Also, inspect the tensioner. Replace it if it is weak.
To recap, the absolute 1st thing to do should be to clean the battery terminals. Clean the top of the battery. Next, take your car to the auto parts store. Ask them to test your battery and the alternator. Go from there.
As RPM's increase, more power is needed to run the engine's electronics. If the alternator is boarder line, the extra power requirements could push it over the edge.
Reminder, the battery light is driven off of battery voltage only. Further, the PCM reduces charging current at WOT (to save load on the motor). Consider if the battery is weak or the terminals are dirty, when the alternator output is decreased by design, the extra power has to be made up by the battery. This could overwhelm the battery's ability to keep up.
That is why it is also good idea to check/clean the battery terminals at the same time. Ensure that the top of the battery is clean as well. Todays car will not run without a solid battery.
Belt slip should be evident on the belt and around the pulleys. But, IMO, what makes the most sense is to TEST the alternator first. Almost any auto parts store will test your alternator for free. Many will do a basic function test with the alternator still on the car.
While the alternator is off, INSPECT the belt looking for evidence of slipping/cracking/wear. If found, replace it. Also, inspect the tensioner. Replace it if it is weak.
To recap, the absolute 1st thing to do should be to clean the battery terminals. Clean the top of the battery. Next, take your car to the auto parts store. Ask them to test your battery and the alternator. Go from there.
twogts4us
15 Year Member
Alternator - have tested and replace if needed. The Sn-95s are known to eat alternators. (or Ford just installed crappy ones)
I'm into my second one after 75k miles (and eleven years) but they ARE expensive if you stick with Motorcraft. I was lucky to find a good one at the junk yard.
thanks for reporting back on what fixed it.A few years ago I started putting a thin layer of vaseline on the battery posts then after hooking up wires put another thin coat on the terminals.
After a week or two I would start to get corrosion build up. Since using the vaseline, never any corrosion whatsoever, looks brand new.
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