Vehicle is a 2003 Dodge Neon, 2.0 liter 4 cylinder engine, 4 speed automatic transaxle. Odometer reading is 290,000+ miles. On Aug 20, 2016 I had to replace the battery due to a weak cell. The starter was laboring in spinning the engine. A battery test at a local auto parts store confirmed a weak cell. Battery was 5 years old so it was not completely unexpected. After replacing the battery and driving the vehicle, the red battery icon lamp illuminated. In the 12 years of owning the vehicle I have never had problems with this lamp illuminating. I used a volt ohm meter to check the charging voltage with engine running at idle. Voltage was 13.0 volts. I used a scan tool and found no diagnostic codes associated with battery charging in the PCM (powertrain control module). I concluded that the alternator was not at fault the charging voltage with engine running at idle. Voltage was 13.0 volts. On Sep 21 the battery icon lamp turned on again. Now it seems more consistent in staying illuminated. Yet I have had no problems in starting and running the vehicle and using all accessories. Last night Sep 23 on a 15 minute trip with vehicle lights and air conditioning operational, I barely made it home with headlamps dimming, air bag lamp illuminating, instrument cluster gauges sweeping clockwise and counterclockwise. Turned engine off and attempted to restart vehicle. Dead battery. There are no diagnostic codes in the PCM related to alternator charging or low system voltage. Today I charged the battery. At engine idle volt meter only shows 12.2 volts. So the alternator is not charging. Local Advance Auto tested the charging system and came to the same conclusion: failed alternator. But I am not so sure. Maybe the field control circuit that regulates the alternator field has an issue - excessive resistance, poor connection, broken wire. The wiring schematic for this vehicle shows a fusible link in the wire that connects the alternator output terminal to the battery wire at the starter. I need to make sure that link has not failed. I want to test the field control circuit. The wiring schematic shows the PCM switches the power side to the generator field. The return wire from the field goes to ground. Can I use a test lamp with one wire connected to engine ground and the other test lamp probe touched to the control wire from the PCM to the generator field? I do not want to overload the PCM generator field driver circuit but need to check that the PCM is supplying electrical power to the field.