03 Explorer Sport XLT - Alernator still not charging after replacing 3 times in 5 days

[Michael Safstrom]

I replaced the original alternator on this SUV along with the battery on Feb 14, 2020, on Mar 18 I noticed windows rolling down extremely slow immediately after starting the engine, checked the voltage gauge and it was very low, after warming up, the gauge went back to normal. Upon traveling to work, the gauge would drop upon accelerating after each stoplight, sign.
The following morning, the same issue. I shut the engine off, to retrieve my multimeter, before the engine warmed up, the meter was reading 12.2-12.3 - After warming up, 14.4. - The Voltage gauge fluctuated throughout the day, then at the end of the day, remained very low, the multimeter showed fluctuations of 1-3 volts...
I pulled the alternator and replaced it on Saturday morning, still 12.2 with engine running... Tested resistance, voltage from all 3 wires on the alternator, all correct until I contacted manufacturer after 3rd replacement this morning... He asked me to probe the excitor wire ( Yellow with white stripe) in the terminal plug... Place the red probe on excitor wire, black probe on Positive battery post... Turn ignition on, not start the vehicle... Reading was -(negative)4.03 _ I placed black probe on Negative Battery post, 12.6 reading.

Tried same test on light green/redstripe wire, same results.

Additionally, the "Lights On" test when first turning key on, the battery light does NOT illuminate. It was working when the original alternator was going bad...

Please do not refer to a "MegaFuse", it does not exist in the 03, Explorer Sport XLT Premium.

Thank you in advance for any assistance.

 

[ranger7ltr]

Bet your battery light blew out and the circuit is not providing voltage to the charge circuit...It has to turn on with the key on engine off to make the alternator charge when the engine is running...Change your battery bulb and the alternator should charge 14-16 volts at the battery positive cable...

 

[Michael Safstrom]

Bet your battery light blew out and the circuit is not providing voltage to the charge circuit...It has to turn on with the key on engine off to make the alternator charge when the engine is running...Change your battery bulb and the alternator should charge 14-16 volts at the battery positive cable...

Just ordered bulbs, not one parts store have them in stock...

 

[koda2000]

If your BATT/CHG light bulb is burnt out (or is not working for any reason) your alternator will not work.

 

[Michael Safstrom]

Just ordered bulbs, not one parts store have them in stock...

The bulb is not blown, just removed the instrument cluster, checked all bulbs, all are good...

What is keeping the battery light from working and this alternator from charging?

 

[koda2000]

With the ignition key in the ON position, 12V power is supplied to the + side if the BATT light. The negative side of the BATT light goes to the voltage regulator (located on the back on the alternator). When the engine is started and the alternator begins producing power, the voltage regulator opens the ground circuit to the BATT light, turning it off.

Check the electrical connectors on the alternator to make sure you don't have a bad/loose connection going back to the BATT light. It's not uncommon for the electrical connections to the alternator to become corroded or burnt. Some alternators come with a new plug for this reason. If you need a new plug, RockAuto sells replacement electrical connectors.

Also, check for continuity on the wire going from the alternator back to the BATT light to make sure it's not broken/open. Consult a wiring diagram for you model to know which wire is which. I want to say it's a green wire with a white tracer, but I'm not sure about this.

Have you checked you fuses? If the fuse that sends 12V power to the BATT light when the key is ON is blown the alternator will not charge.

 

[Michael Safstrom]

With the ignition key in the ON position, 12V power is supplied to the + side if the BATT light. The negative side of the BATT light goes to the voltage regulator (located on the back on the alternator). When the engine is started and the alternator begins producing power, the voltage regulator opens the ground circuit to the BATT light, turning it off.

Check the electrical connectors on the alternator to make sure you don't have a bad/loose connection going back to the BATT light. It's not uncommon for the electrical connections to the alternator to become corroded or burnt. Some alternators come with a new plug for this reason. If you need a new plug, RockAuto sells replacement electrical connectors.

Also, check for continuity on the wire going from the alternator back to the BATT light to make sure it's not broken/open. Consult a wiring diagram for you model to know which wire is which. I want to say it's a green wire with a white tracer, but I'm not sure about this.

Have you checked you fuses? If the fuse that sends 12V power to the BATT light when the key is ON is blown the alternator will not charge.

Wires to/on the alternator, large Black w/ Orange stripe bolted to the alternator, below is a clip plug, 1 Yellow w/white stripe, other smaller is light green w/redstripe

 

[koda2000]

Wires to/on the alternator, large Black w/ Orange stripe bolted to the alternator, below is a clip plug, 1 Yellow w/white stripe, other smaller is light green w/redstripe

Light green with red tracer according to the wiring diagram I'm looking at. Goes from BATT light on dash to the voltage regulator on the alternator.

BATT light is feed 12V power with key ON from fuse number 15.

 

[Michael Safstrom]

Light green with red tracer according to the wiring diagram I'm looking at. Goes from BATT light on dash to the voltage regulator on the alternator.

BATT light is feed 12V power with key ON from fuse number 15.

Judging by the owners manual, fuse box under the hood #15 is not used - fuse box #15 in the cab of truck is 4x4 module?

 

[koda2000]

Judging by the owners manual, fuse box under the hood #15 is not used - fuse box #15 in the cab of truck is 4x4 module?

Well I don't have a wiring diagram for an '03. You need to look at a charging system wiring diagram for you specific model year. Usually Ford stays with the color of wires, but they can always change power supply sources from year to year. I don't know what else to tell you. You need to determine why the BATT/CHG light isn't working. Either no power or no ground.

 

[410Fortune]

Does this 03 have a ALT or GENERATOR fuse? Usually there is a 15 amp mini fuse that provides the power for the batt light in the instrument cluster
Check your fuses

 

[Michael Safstrom]

Well I don't have a wiring diagram for an '03. You need to look at a charging system wiring diagram for you specific model year. Usually Ford stays with the color of wires, but they can always change power supply sources from year to year. I don't know what else to tell you. You need to determine why the BATT/CHG light isn't working. Either no power or no ground.

Waiting on a friend to come by and assist, I have the Chilton Manual for the 02-03 Explorer/Mountaineer - Charging diagram showing light green /red wire going to the powertrain control module, Yellow/white wire shows in the diagram as Orange/light blue... w/w fusible links, then to yellow/white to battery junction box

 

[Michael Safstrom]

Does this 03 have a ALT or GENERATOR fuse? Usually there is a 15 amp mini fuse that provides the power for the batt light in the instrument cluster
Check your fuses

Just checked all fuses, all good

 

[ExploringOptions2004]

With the ignition key in the ON position, 12V power is supplied to the + side if the BATT light. The negative side of the BATT light goes to the voltage regulator (located on the back on the alternator). When the engine is started and the alternator begins producing power, the voltage regulator opens the ground circuit to the BATT light, turning it off.

Check the electrical connectors on the alternator to make sure you don't have a bad/loose connection going back to the BATT light. It's not uncommon for the electrical connections to the alternator to become corroded or burnt. Some alternators come with a new plug for this reason. If you need a new plug, RockAuto sells replacement electrical connectors.

Also, check for continuity on the wire going from the alternator back to the BATT light to make sure it's not broken/open. Consult a wiring diagram for you model to know which wire is which. I want to say it's a green wire with a white tracer, but I'm not sure about this.

Have you checked you fuses? If the fuse that sends 12V power to the BATT light when the key is ON is blown the alternator will not charge.

Not to get off topic but it is cluster related. Is the indicator battery test light apply for all things on the cluster? Say for example i wanted to test the coolant temp light... My temp gauge isnt working. I tested engine temp sensor and resistance appears to change accordingly also had a good Vref and ground at the plug. My temp light does work so would this be indictive of a bad stepper motor? Also tach and Speedo gauges arent working. Everything else is operable including all cluster lights

 

[410Fortune]

Check fuses for instrument cluster




check fusible links in the yellow / white wire
Should be hot all times at the alternator, this is why it has fusible links. I hate that they went back to fusible links, before 03 there was an actual alt fuse in the fuse box.
You need to make sure all battery terminals and wires including the ground side are clean and free of corrosion
Forget about buying re manufactured alternators from the parts stores, they are garbage, all NEW ONLY

 

[Michael Safstrom]

Check fuses for instrument cluster




check fusible links in the yellow / white wire
Should be hot all times at the alternator, this is why it has fusible links. I hate that they went back to fusible links, before 03 there was an actual alt fuse in the fuse box.
You need to make sure all battery terminals and wires including the ground side are clean and free of corrosion
Forget about buying re manufactured alternators from the parts stores, they are garbage, all NEW ONLY

All fuses good, I did a voltage check with multimeter... Black orange wire 12v, Yellow white 12v - Light green red stripe wire. 0v ignition off, between 3-4v with ignition on

 

[Michael Safstrom]

Tried a hot jump to see if alternator would start charging, directly from + battery terminal to green/red wire, no changes... Could this be PCM issue, smart charging system?

 

[Michael Safstrom]

Not to get off topic but it is cluster related. Is the indicator battery test light apply for all things on the cluster? Say for example i wanted to test the coolant temp light... My temp gauge isnt working. I tested engine temp sensor and resistance appears to change accordingly also had a good Vref and ground at the plug. My temp light does work so would this be indictive of a bad stepper motor? Also tach and Speedo gauges arent working. Everything else is operable including all cluster lights

Alt/Batt light is the only one not lit when first turning key on, all other lights,gauges working

 

[ExploringOptions2004]

Still not charging huh?