I have a 2005 Lincoln Town Car Signature Series the alternator is testing good, new battery, and new starter. The voltage light comes on when driving sometimes and if I continue to drive the car stalls if I come to a complete stop. After waiting about 10 minutes the car starts again and drives. If I drive the car with no radio or heat it does happen as fast. What could be the problem?
Make sure terminals on battery & alternator are clean and tight.
Make sure engine ground strap is in good condition.
Make sure battery to body ground connection is clean and tight.
Here's something else to consider in your troubleshooting.
Your alternator's voltage regulator is controlled by your PCM.
The alternator has the lug with the 12 volt heavy wire to your battery and it has a 3 pin connector.
1 pin is for Bat+ (around 12 volts)
1 pin is for the communication signal from your PCM to the Alternator.
1 pin is for communication signal from your Alternator to the PCM.
Any intermittent shorts or "opens" in the wiring of any of those, or an issue in the 3 pin alternator connector itself, would trigger the PCM to illuminate the "voltage light" and cause a charging issue.
The thing is that it's an intermittent problem and the easiest way to figure out "what's happening", is when it's happening.
Maybe a way to rule out a problem with any of those 3 circuits would be to keep a multimeter in your glove box.
When your Town Car starts acting up, pull over and check the voltage output on that Bat+ (heavy wire) at your alternator.
It would be interesting to see what voltage it's putting out during the problem. It should be putting out over 14 volts. It would be an issue to consider if it were putting out less than 12 volts.
