Battery Charge Warning Light
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Junior User
Joined: Jul 2013
Posts: 57
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From: Austin Tx
Battery Charge Warning Light
In a F150 I6 300 4.9 I have a BLINKING battery charge warning light. It has been going off as long as my friend has owned this truck. According to the manual the light will stay on if there is a charging problem. It does not mention it blinking. If this points a charging problem the battery in 14 months is still fine.
Anyone have any Ideas why it is blinking?
Anyone have any Ideas why it is blinking?
Tuned
Joined: Dec 2012
Posts: 372
Likes: 5
From: 85716
Exerpt from the service manual:
Put a volt meter on the batter terminals. With engine off, it should read 12.3 to 12.8 (ish). With engine at idle, it should read at least 13.5 to 14.5 (ish).
If its not reading 13 volts or above, your alternator is not charging (hence the light on the dash illuminates). Don't rely on the gauge on the cluster it's not very accurate/precise.
Charging System Warning
With the key in START or RUN, battery voltage is present at the charge indicator. If the generator (GEN) (10346) is not generating power, the voltage regulator inside the generator grounds the charge indicator through Circuit 904 (LG/R). The charge indicator illuminates.
When the generator is generating power, the voltage regulator inside the generator applies battery voltage to the charge indicator through Circuit 904 (LG/R). With battery voltage present at both ends of the charge indicator, there is no current flow and the charge indicator does not illuminate.
With the key in START or RUN, battery voltage is present at the charge indicator. If the generator (GEN) (10346) is not generating power, the voltage regulator inside the generator grounds the charge indicator through Circuit 904 (LG/R). The charge indicator illuminates.
When the generator is generating power, the voltage regulator inside the generator applies battery voltage to the charge indicator through Circuit 904 (LG/R). With battery voltage present at both ends of the charge indicator, there is no current flow and the charge indicator does not illuminate.
If its not reading 13 volts or above, your alternator is not charging (hence the light on the dash illuminates). Don't rely on the gauge on the cluster it's not very accurate/precise.
Posting Guru
Joined: Jan 2002
Posts: 1,346
Likes: 8
From: Baltimore
You didn't say the year of the truck.
If your alternator doesn't have a seperate battery output terminal on the back of the alternator, the battery charge voltage comes from the regulator plug.
The plug over heats and the wires melt. It is a very common problem.
Most auto part stores sell a replacement pigtail.
If your alternator doesn't have a seperate battery output terminal on the back of the alternator, the battery charge voltage comes from the regulator plug.
The plug over heats and the wires melt. It is a very common problem.
Most auto part stores sell a replacement pigtail.
Posting Guru
Joined: Jan 2002
Posts: 1,346
Likes: 8
From: Baltimore
The 94 alternator doesn't have a over heating plug problem.
As noted in the 2nd post, the alternator voltage regulator is detecting the
alternator voltage is out of spec. and turns the charge light on. Since
it's blinking verify the regulator plug and battery terminal cable is in good shape and
making a good connection.
Otherwise take off the alternator and have it test at the auto part store.
Could be something as simple as worn out brushes which are easily replaced.
As noted in the 2nd post, the alternator voltage regulator is detecting the
alternator voltage is out of spec. and turns the charge light on. Since
it's blinking verify the regulator plug and battery terminal cable is in good shape and
making a good connection.
Otherwise take off the alternator and have it test at the auto part store.
Could be something as simple as worn out brushes which are easily replaced.
pedant
Joined: Jan 2008
Posts: 23,576
Likes: 38
From: EXTREME southwest CT
Some trucks used the fire prone 2G up to '96.
If it has no fan on the front it is a 3G.
It is the square charge plug with two 10Ga. black/orange wires and a white/black that melts on the 2G, not the regulator plug.
The regulator and brushes are usually both changed on the 2 & 3G alternators because the regulator screws also hold the brushes in place.
Simple to do with a T-20 screwdriver
I would suggest getting a white rather than a black or gray regulator.
White is Load Response Control (soft start) and these work fine for all vehicles.
This one fits the 'D' shaped plug.
Cross the part number at any local auto parts store.
Voltage regulator for Ford 3G Alternator - 14030 - R14030
If it has no fan on the front it is a 3G.
It is the square charge plug with two 10Ga. black/orange wires and a white/black that melts on the 2G, not the regulator plug.
The regulator and brushes are usually both changed on the 2 & 3G alternators because the regulator screws also hold the brushes in place.
Simple to do with a T-20 screwdriver
I would suggest getting a white rather than a black or gray regulator.
White is Load Response Control (soft start) and these work fine for all vehicles.
This one fits the 'D' shaped plug.
Cross the part number at any local auto parts store.
Voltage regulator for Ford 3G Alternator - 14030 - R14030
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