Voltage and Ballast Resistor Question

I assume you are talking about the ammeter. Sounds like it's overcharging.

You need to run some simple tests, and determine if it's

the battery

a wiring problem

the voltage regulator

1 If the battery has a a problem, is is down from sitting, it may be charging hard. First order of business is EITHER charge the battery and have it "load tested" and if possible, checked with a hydrometer --- or temporarily substitute a known good battery out of a second car

2 AFTER you know the battery is OK, run the car at an RPM to simulate "low to medium" cruise and measure voltage with a multimeter right at the battery. With the engine warm (the regulator is affected by temperature) the system should "run" at about 13.8--14.2V, not less than 13.5, not more than 14.5

If this is high, you need to run some more tests. Post back to this thread with results, and we'll go from there


ON the ballast resistor, the factory manuall shows the 4 terminal ballast is 5 ohms on the ECU side and .5 (1/2) ohm on the coil side. I believe these changed somewhat over the years, and one other source shows the coil side at 1.2 ohms. I would not worry about it unless it is intermittent or open.

Do you have a factory shop manual for your car? 12V test lamp? multimeter? AND what year/ model we working on here?