Battery Light

[Rodeo Joe]

Re: Battery Light

Have you checked the water level? I've heard that can cause it also.

Joe

[Señor Gar]

Re: Battery Light

From looking at the WD Manual, if the light is coming ON when the voltage is normal the regulator in the alternator may be sending a faulty pulse-width modulated signal to the Powertrain Control Module > Auxiliary Junction Box > Instrument Cluster. The signal could also be corrupted in one of these modules.

[HKS]

Re: Battery Light

From looking at the WD Manual, if the light is coming ON when the voltage is normal the regulator in the alternator may be sending a faulty pulse-width modulated signal to the Powertrain Control Module > Auxiliary Junction Box > Instrument Cluster. The signal could also be corrupted in one of these modules.

Brad,

PCM Alternator Schematic.

Sorry about the pix quality. What I sent was better.

It might still be the alternator. Substitution is best for troubleshooting. OK while checked is not good sometimes.

[Brad]

Re: Battery Light

12.2v All off
11.71 Ignition and radio on
10.6v During cranking
14.4v While running
Was able to get a few reading while light comes on, absolutely zero fluctuation in Volts.
While light was on, going WOT, light comes off, still no fluctuation in Volts reading before, during, or after

[HKS]

Re: Battery Light

12.2v All off
11.71 Ignition and radio on
10.6v During cranking
14.4v While running
Was able to get a few reading while light comes on, absolutely zero fluctuation in Volts.
While light was on, going WOT, light comes off, still no fluctuation in Volts reading before, during, or after

14.45 sounds right for the alternator voltage. I assume you or mechanic also checked all battery and alternator and ground connections.

Does anyone know if the PCM monitors charging voltage or charging current?
To monitor current, you need a remote sensing amp-meter which needs to be in series with the main charging terminal +.
I
will look and see if such a device is available. What may work is a 1/2 ohm high wattage resistor. Voltage is measured across the resistor. Look for a fluctuation in voltage representing a drop in current.
Or start replacing parts like a Ford garage would do.

This picture is using 21" of #15 wire as a current sensing resistor.
https://www.google.com/search?q=amme...AQIRw&dpr=1.25
HKS

[HKS]

Re: Battery Light

Brad,
In case you find the time and want to locate the PCM, I attached pictures. Removing and reconnecting PCM connectors is only half as bad as replacing the PCM. Replacing, requires removing things by the glove box.

Just unplugging and reconnecting the 3 PCM connectors can be done from the engine compartment. I requires removal of the entire cabin air filter box. Disconnecting and reconnecting may knock off corrosion that is giving you the intermittent battery light.

See the pictures.

For me, this enough frustration to consider trading a 2002 for a 2003. Can anyone chime in as to where the PCM is located on a 2003/5 bird?

Years ago, I was going to see if I can get a PCM re-flash to get better performance but his would require removing the PCM just to find the correct part number and determine if I needed the upgrade. Dealers probably have a way of finding out for $100+. There are many versions.

HKS

[Señor Gar]

Re: Battery Light

Can anyone chime in as to where the PCM is located on a 2003/5 bird?

Same place and procedure for all the 02-05 cars.

Years ago, I was going to see if I can get a PCM re-flash to get better performance but his would require removing the PCM just to find the correct part number and determine if I needed the upgrade.

An OASIS report will give you your PCM 'Engine Calibration' number which is what differentiates the modules.
My dealer, using his IDS scan tool, recently recalibrated my PCM through the OBDII port (to the right of the steering column under the dash) after I changed from a SST shifter to a Base shifter.
The recalibration consisted of downloading the new calibration from Ford Tech Support to the IDS and then connecting the IDS to my OBDII port to reflash my PCM.

This is my old calibration ...

[HKS]

Re: Battery Light

Same place and procedure for all the 02-05 cars.
An OASIS report will give you your PCM 'Engine Calibration' number which is what differentiates the modules.
My dealer, using his IDS scan tool, recently recalibrated my PCM through the OBDII port (to the right of the steering column under the dash) after I changed from a SST shifter to a Base shifter.
The recalibration consisted of downloading the new calibration from Ford Tech Support to the IDS and then connecting the IDS to my OBDII port to reflash my PCM.
This is my old calibration ...

Gar, Thank you very much for the info.

My PCM was replaced under warranty years ago. So, should I assume OASIS has that new information?

There was a detailed list of PCM's that could be upgraded on this site but it required a PCM number. I would need to spend a $100+ just to find out I already have the latest upgrade. But considering the labor involved to remove the module just to find the part# ,it may be worth the $100.
The pictures I uploaded show only halve of the procedure for replacing the PCM.

Next question. Is the part number visible from the glove compartment (2nd half removal procedure) or the engine compartment (1st half removal procedure) during the partial teardown?
HKS

[Señor Gar]

Re: Battery Light

So, should I assume OASIS has that new information?

Yes

Next question. Is the part number visible from the glove compartment (2nd half removal procedure) or the engine compartment (first half removal procedure) during the partial teardown?
HKS

There may be a tear tag accessible on the left side of the PCM if you reach up behind the glove box. Use a mirror and flashlight to see it it's there.
I didn't know this until I removed my PCM, all but the wire harness, so I stopped there and was able to get a photo of the label on top.


This is my old tear tag removed from the tape that was holding it to the left side of my PCM.
The dealer can use this number to get your calibration number.

[HKS]

Re: Battery Light

There may be a tear tag accessible on the left side of the PCM if you reach up behind the glove box. Use a mirror and flashlight to see it it's there.
I didn't know this until I removed my PCM, all but the wire harness, so I stopped there and was able to get a photo of the label on top.

Thanks for the very valuable info.

I will see if I can accomplish this with mirrors. I am no longer limber like Hudini but I will make an attempt at locating this number. I assume I will not need any under hood work to accomplish my task.

HKS

[Señor Gar]

Re: Battery Light

I assume I will not need any under hood work to accomplish my task.

No, but you will need to bend over, LoL.

[HKS]

Re: Battery Light

No, but you will need to bend over, LoL.

Bending over yes. Standing on my head no.

[Señor Gar]

Re: Battery Light

Standing on my head no.

I managed to right the pic so you wouldn't have to

[Brad]

Re: Battery Light

Follow-up:

I haven't had the alternator replaced yet so I still don't know if it's the cause for sure but it sure sounds like it.

Was able to have it tested while I had the battery light illuminated. Guess what? When my light it on it's OVERCHARGING!!!

The cigarette lighter apparently is not a good location to test the voltage, was getting readings of 14.2 volts inside the car while the technician got 15.5+ volts at the battery.

Installing a temporary wire to the battery for testing was a great idea that I should have done!

I'll update this once I get the alternator replaced to confirm.

[SugarDaddy]

Re: Battery Light

Today, the battery warning light came on after a few minutes and stayed on for most of the drive around town. While driving, I plugged in my plug-in volt meter into the power outlet on the dash and got readings of 14.2 to 14.3 volts while driving. Those readings appear to be OK.

After returning home, I checked the voltage at the battery with my own multimeter, with the engine off, and with the engine running while the battery warning light was illuminated:

Engine off: 12.6 volts ( this should be OK)
Engine running at idle: 14.5 volts (This should be OK)
Engine running with headlights on and AC on: 14.5 volts (this should be OK)

I also checked the battery voltage output using the "Torque" app on my Android phone, and my bluetooth OBD II ELM adapter:

Engine running at idle: 14.2 volts (nothing out of the ordinary here)

I also checked for any Fault Codes with the "Torque" app.
But, no fault codes were found.

The plug-in volt meter readings were between 14.2 to 14.3 volts during these latest tests with the engine running at idle at home.

All these readings appear to be within proper levels, so I have no idea why the battery warning light is illuminating and now staying on? It's a mystery to me!