Dodge Fault Codes?

Question

My 1990 Dodge B250 van starts fine then quickly revs itself up to 2500 to 3000 RPM. (In the winter months this doesn't happen, the engine just floods itself, stalls, and will not start again for 30 to 45 mins.)
I asked a mechanic who suggested the coolant temp sensor is faulty and it's telling the computer the engine is stone cold, even at normal operating temperature. As a result the computer is calling for massive amounts of fuel which it is dumping down the throttle body.

I checked the fault codes and got the following:
12- Power Fail (no big deal)
22- Coolant sensor out of range
33- Standard code for vehicle w/o air conditioning (so I'm told)
41- Alternator field control circuit open or shorted (I don't understand this one)
46- Battery voltage too high during charging, or system voltage too low ( Once again, I don't understand this one either. I have not observed any electrical issues at all)

A friend says a bad MAP sensor will cause this?? HELP!!

Answer 1

IMHO, you should listen to your mechanic. If your coolant temp sensor is "out of range", the engine computer is getting a signal that it knows is wrong, and may be caused by an intermittently "open" circuit. However, when the sensor is sending an erroneous signal, it may be reading -30*F. Now, if it's 80*F outside, this will certainly explain the flooding and high revving, because the computer is dumping enough fuel into the engine for the -30*F, and raising the idle speed to overcome the engine friction of an extremely cold engine. And it wouldn't bother as much in cold weather, because the outside temp is much closer to what the temperature sensor is actually reading. So, first thing to do is replace the coolant temperature sensor. Now, the charging system (codes 41 and 46) is controlled by engine temperature and ambient temperature. So there may not be a problem, these may just be erroneous fault codes due to the coolant temperature sensor being bad, and confusing the charging portion of the engine computer. Code 12 means the battery has been disconnected within the last 255 starts, nothing to worry about, especially if someone has erased fault codes with a scan tool. So my advice would be replace the coolant temp sensor, erase all the fault codes, and drive the vehicle. If any fault code(s) re-occur, repair them at that point. But I feel that the coolant temp sensor may cure all your problems! HTH!! Good Luck!!

Answer 2

Code # 41 & 46 suggest a voltage regulator problem. I suggest a comprehensive test with an accurate volt meter. If voltage is too high it can cause sensors to send inaccurate messages to central processor. That issue should come first. If indeed that is a problem the other issues may go away once the voltage is correct.