As some of you might of followed my last thread
http://www.forabodiesonly.com/mopar/showthread.php?t=155522.
My alternator decided to die on me as well as my ECU. Finding out that my alternator was dying the ammeter gauge was reading in the negative side before my car decided to die on me. After having my alternator tested at two different places and failed each test I decided to get a new alternator. My ECU, after a long day of troubleshooting occurred, was the deciding factor as to why my car wouldn't start anymore. I have a slant six and was using the black ECU box for several years, we swapped it out with the orange mopar box that is typically recommend for the little bit higher RPM range engines.
My question is this. While the alternator, coil and ECU were replaced. My ammeter gauge reads at directly between the two lines at the top of the gauge when my car is just idling , yet when I push the accelerator the needle jumps to the positive side to the second to last tick mark on the gauge, yet when I come to a stop light it falls just below the top two tick marks into the negative side a little bit.
Before any of these things were changed out, for several years the ammeter was always reading right between the top two marks 100% of the time. What would be causing this sudden change now ? could it be switching to the orange ECU box ? or something else gone wrong. Thank you for any suggestions.
Here is what might be happening, and might just be related to the "no run" condition.
The path of "ignition run" that is, the traditional "dark blue" that feeds the ignition system, ALSO FEEDS the regulator, the alternator field, and a couple of other things if used.
THIS IS THE ONLY wire coming into the engine bay that is hot from the key "in run."
It is subject to "voltage drop" because of problems with the bulkhead connector, the connector on the ignition switch, possibly connections in the bulkhead for the alternator.
THIS IS WHY I'd like you to see exactly what you have.
Turn the key to run, engine off. Compare battery voltage right at the battery, to the voltage at the "dark blue" feeding the ignition. More than 1/2 volt difference is too much.
Another way to check this is to measure the voltage drop directly. Put one meter probe directly onto the battery positive post, and the other probe on the dark blue feeding the ignition. (key side of the ballast.) If the meter reads more than 1/2 volt, you have a "drop" problem in the circuit I described above.
NOW why does this affect the alternator?
Because this "dark blue" "run" wire ALSO FEEDS the ignition terminal of the regulator, and the regulator is "sensing" this voltage to determine what voltage to set the alternator at. If the regulator "would like to" charge at 14V, and you have .5 (1/2) volt drop through this dark blue circuit, the voltage regulator WILL ADD THAT DROP to the charging voltage, and you will see 14 + .5, or 14.5V (example) at the battery.
Since you have BOTH had run problems AND now have what seems like an overcharge problem, this is as I see it.
