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InkedFestiva 1989 Alternator (Lamp).jpg InkedFestiva 1990 Alternator (Lamp ).jpgFestiva Charge Warning Indicator (from 1992 EV TS Manual).jpgFestiva 89 manual Alternator Regulator Connection.jpg
Above page from 1990 - 1993 manual (Alternator with S/L plug)...........................Above page from 89 manual
Here is some information that may be helpful to folks having alternator charging issues.
The "Charge" light on the instrument panel is a key component that must be present and working properly or the alternator will not output a charging current.
The positive side of that light comes from the battery (BK) to the main fusible link then (W) to the ignition switch then (when on) (BK/W) to the meter fuse then (BK/Y) to the charge indicator on the instrument panel. The negative side goes thru a 100 ohms resistor followed by a diode (-->| ) built into the instrument cluster and then (BK/R) on through the wiring harness to the alternator (one of the double wires (BK/R) on the side or top plug depending on the year of the Festiva). The "B" (battery) terminal (not always labeled) is for the main charging wire to the battery. The smaller 89 alternator has a I (opposite the L) label and hard to see, which goes to the Main Relay, and then thru the engine fuse to the ignition switch, condenser and ignition coil via BK/W wire.
When the ignition is turned to on the Charge/Battery light goes on because the wire going to the alternator is grounded internally by the regulator which also detects the 100 ohms resistance to the current being provided.
As the alternator spins and starts producing power the charge light goes dim then eventually out on the panel but the 100 ohms resistance across that wire is still present and detected by the alternators internal regulator so power continues to be produced. However if that light burns out, your alternator will stop producing current. I'm no electrical expert so I can't explain all the specifics of how all this works. I know the diode only allows current to flow in the direction of the arrow.
At least this is the way I understand it. If anyone has better knowledge of this and want to correct or add to this, please feel free to do so.
My 92 and 93 manuals show the red wire from the S (for battery voltage "S"ense wire) terminal of the alternator going to the "Head" main fusible link back to the battery positive terminal to measure voltage. In both the white wire from B terminal on the side goes back through the main fusible link to the battery positive terminal for charging.
The other single wire blade terminal on the side of both alternators is to send power to the choke heater. There seems to be no single standard for alternator connector labels in general because different makes have different letters for the same terminal type so you have to be careful.
Here is a video that explains how the 3 wire alternator works and how the charge light breaks the connection when burned out and thus prevents the alternator from charging. https://www.youtube.com/watch?v=7Ih-TQSvhss
Another page which better explains how the alternator works https://auto.howstuffworks.com/alternator1.htm with the charging system https://auto.howstuffworks.com/alternator.htm
J38R DLX With Tach.jpg J38R STD Without Tach.jpg
Cluster With Tach (J38R DLX) .................................................. ............................Cluster without Tach (J38R STD)
Above page from 1990 - 1993 manual (Alternator with S/L plug)...........................Above page from 89 manual
Here is some information that may be helpful to folks having alternator charging issues.
The "Charge" light on the instrument panel is a key component that must be present and working properly or the alternator will not output a charging current.
The positive side of that light comes from the battery (BK) to the main fusible link then (W) to the ignition switch then (when on) (BK/W) to the meter fuse then (BK/Y) to the charge indicator on the instrument panel. The negative side goes thru a 100 ohms resistor followed by a diode (-->| ) built into the instrument cluster and then (BK/R) on through the wiring harness to the alternator (one of the double wires (BK/R) on the side or top plug depending on the year of the Festiva). The "B" (battery) terminal (not always labeled) is for the main charging wire to the battery. The smaller 89 alternator has a I (opposite the L) label and hard to see, which goes to the Main Relay, and then thru the engine fuse to the ignition switch, condenser and ignition coil via BK/W wire.
When the ignition is turned to on the Charge/Battery light goes on because the wire going to the alternator is grounded internally by the regulator which also detects the 100 ohms resistance to the current being provided.
As the alternator spins and starts producing power the charge light goes dim then eventually out on the panel but the 100 ohms resistance across that wire is still present and detected by the alternators internal regulator so power continues to be produced. However if that light burns out, your alternator will stop producing current. I'm no electrical expert so I can't explain all the specifics of how all this works. I know the diode only allows current to flow in the direction of the arrow.
At least this is the way I understand it. If anyone has better knowledge of this and want to correct or add to this, please feel free to do so.
My 92 and 93 manuals show the red wire from the S (for battery voltage "S"ense wire) terminal of the alternator going to the "Head" main fusible link back to the battery positive terminal to measure voltage. In both the white wire from B terminal on the side goes back through the main fusible link to the battery positive terminal for charging.
The other single wire blade terminal on the side of both alternators is to send power to the choke heater. There seems to be no single standard for alternator connector labels in general because different makes have different letters for the same terminal type so you have to be careful.
Here is a video that explains how the 3 wire alternator works and how the charge light breaks the connection when burned out and thus prevents the alternator from charging. https://www.youtube.com/watch?v=7Ih-TQSvhss
Another page which better explains how the alternator works https://auto.howstuffworks.com/alternator1.htm with the charging system https://auto.howstuffworks.com/alternator.htm
J38R DLX With Tach.jpg J38R STD Without Tach.jpg
Cluster With Tach (J38R DLX) .................................................. ............................Cluster without Tach (J38R STD)
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