Hi all

have 2012 RT Limited 3.6 pentastar. Now having aroung 100k miles. Wife came from work with major issues (blinking instrument panel, no abs, no climatization), after I open hood - see boiling battery and water flow from it, measure around 17 volts on clips. I take off alternator for rework, but right after i put it back, near heart attack came to me - there was 19volts on battery clips, so i take alternator back to shop for waranty, they showed me, alternator is all ok, charing nice 14,3 volts, issue is in my car. so I again put everything together. When there is nice sunny weather for few days, have around 14 volts, yesterday we have again storm there, so today i measure around 18 volts. Car don't move for 3 months, curently i have in a barn (so no direct rain, just wet). When i check it with witech (fabric diagnosis), there is error in near every module regarding high voltage and also request to alternator from PCM looks like rollercoaster - it is possible it is wrong PCM module, or should I look somewhere in harmness. Maybe someone have harmnes diagram for this kind of car?

 

Wow, 19 volts!!! If the shop that reworked your alternator thinks your car can magically boost the alternator voltage 14.3 V to become 19 V at the battery, I'd say they're in the wrong line of business and shouldn't work with electricity at all. No car has any kind of "voltage booster" of this kind and the battery cannot, in any way, have 19 V on the poles unless the alternator provides that!!! Apart from special circuits, like the ignition (assuming petrol), the alternator has the highest voltage in the system (at least as long as it's charging). From there, you'll always see lower and lower voltages the "longer" from the alternator you get (voltage drop). It's called physics. Having said that, all alternators have some means of controlling the charge so the battery is always charged with a suitable voltage. This voltage may be adjusted to compensate for cold weather, battery overtemp and other factors, but always within reasonable limits, like 13.8-14.8 V or so. What seems to be the case with your alternator is that when the car tries to regulate the voltage the alternator produces, the signal is interpreted in an incorrect way by it, and it massively overcharges your battery, potentially destroying electronics as well.

There MAY still be something wrong with your car, like sending an incorrect signal to the alternator, but the alternator certainly doesn't keep its output within allowable limits and IS defective. If the shop thinks it's so great, why can't they just replace it for you?

Best of luck!

/Fredrik

PS Harness, not harmness

 

VMdiesel - thanks for correction, sorry, english is not my natural language, on other hand using it a lot (same as the rest of the world)

i try to change alternator and the issue persist, so means it get wrong signal from PCM (i don't like this way to change pcm), or some rotten cable. does anyone know where cables are heading from alternator? i would try to replace them first, as it is quite cheaper solution, but don't want to cut whole path of cables.