I own a 92 Grand Caravan with Check Engine codes of 12 and 41. The 12 is not listed in my Chilton’s manual for this year. Internet information indicates that the 12 code means “battery disconnect”. My manual indicates the 41 is “Alternator Field not switching properly”. What do these indicators actually mean. Does it mean imminent breakdown of something or do I have time to get it to the shop in the near future? Do you recomend a dealer or a trusted shop that we normally use? The local dealer has treated us well too when used. Thanks
12: Battery or computer recently disconnected
41: Alternator field control circuit open or shorted
You can generally ignore the 12 code. It may be related to the 41 code if battery voltage drops far enough. Check the connections and wiring to the alternator for looseness, corrosion, and shorts. Disconnect the negative battery cable first!
Oh, and if the alternator is bad, your regular mechanic can handle the job. But the problem could be the powertrain control module, which contains the voltage regulation circuitry, IIRC. (Check those wires also, come to think of it.)
Does the little red BATT or ALT light (whichever) illuminate when the key is turned to the RUN position?
If the light if off or erratic then that could be your 41 code.
I do not have a schematic for this vehicle but a battery disconnect code could possibly be caused by a circuit breaker momentarily popping open. It seems to me there is a breaker in the system that provides power to all of the electrics but my memory is real fuzzy on this.
If so, the bigger question could be why that breaker opened.
Have a neighborhood mechanic disconnect the battery cables, and abrasively clean inside the battery terminal loops. Then, sand the battery posts. Loosen, and re-tighten, the wires/cables connected to the starter and the alternator.
Thank you NYBo, ok4450, and hellokit. I did wire brush the batt cables and posts; and loosened the wires on the alternator and sprayed them with contact cleaner (while the batt was disconected). After several runs with the vehicle, the CE light has not appeared. I will take it to my favorite mechanic if the problem persists. For now, my wife (her car) is more comfortable about driving it again.
This is what I like to hear…success! [Just plain feedback (positive, negative, or neutral) is appreciated, also.]