Chrysler Repair: 1996 Caravan Battery idiot light & code 41 code 31, crankshaft sensor, code 41

Question
I have a 1996 Caravan with a 3.3L, automatic 3 spd. The battery idiot light on the instr. panel glows faintly or brightly then not all at all. It is very sporadic.

I checked the codes and 41 came up. Code 31 also came up twice in a row on the same code read.

The battery was replaced a year ago.

The van has 275,000 km on it. The oil smells a little like gasoline - the heads were redone at 200,000 km.

The tranny leaks a little oil - I have bought a new filter and gasket and fluid and will replace the existing shortly.

The last breakdown was caused by the crankshaft sensor - the van's engine would warm up and then quit - we had to wait for it to cool down to restart. The sensor was replaced thanks to information from your website here and all was well up until yesterday.

Questions: What gives with the codes (41 and 31)? Whay the doubled code 31? Why the fuel smell in the engine oil? Does a low fluid level in the tranny cause overheating which may cause the code 41?

Thank you in advanhce for your time and comments on this.

Bob In Ontario.

Answer
Hi Bob,
Thanks for the good history.
The code 41 means there is either an open or short in the field coil circuit of the alternator (probably an open if the voltage is low which is the cause of the battery light most likely). So check the wire at the alternator that is dark green/orange for 12V to be present when the engine is running and also separately check that the connection between the dark green wire and pin 20 at the powetrain controller is patent. If you have those two verified and still get the light "on" I would suspect the alternator field coil is faulty.
The 31 says there is a problem with the gas vapor control system. So take a look at all the hoses and connectors for that, using the underhood sticker as a road map. That may well be the source of the fuel smell. The only reason I can think for the oil to smell such would be a faulty injector but that should set another code in the oxygen sensor, for example, which you don't have. So see if you can deal with the vapor collection system first and see what happens after that.
I am not sure why there would be a double 31. But you could try disconnecting the battery for a few minutes, then drive it for a few trips and recheck the codes. The disconnect will cancel the old codes but set a 12 code ("battery disconnected from controller recently") and what ever else is still wrong.
I don't think the tranny has anything to do with the 41 code.
Good luck on your troubleshooting.
Roland