Chrysler Repair: 1997 Dodge Grand Caravan: codes 21,47,51,66, dodge grand caravan, digital communication system

Question
97 Grand caravan with 3.3 engine. Engine light stays on .turned ignition switch 3 times and got these codes.12 21 66 66 21 21 51 47 55. could you tell me what they are. Thanks, Dan

Answer
Hi Dan,
I don't believe the multiple presentation of the codes is important, but if you would like to erase them all and start fresh you could disconnect the battery for 5 minutes or so and then drive it anew for a few trips and get current codes. In any case,
21 means one or both of the oxygen sensors are showing voltage readings that are abnormal.
47 means to voltage output of the alternator is not properly controlled, reads too low
51 means the mixture is too lean, perhaps is related to the oxygen sensor issue
66 means that at some point in time in the past the digital communication system wasn't working well between the engine controller, the transcontroler, and/or the body controller. If the shifting and the functioning of the engine, and the electrical system of the cabin are ok now then it is moot.
Otherwise, some analysis of the system with a readout box may be required.
The 12 means that the battery voltage to the engine controller was disconnected sometime in the fairly recent past (battery clamp removed?)
55 means 'end of readout'
My suggestion would be to get a free readout with a plug-in code reader to get the OBD-II 4-digit codes which for example will tell you which oxygen sensor is wrong, and which part of the digital communication is broken open. Autozone parts stores will often do the readout for free. If not go to an independent garage which might offer to do it for under $40. Get the specific fault numbers, ask what they mean, what they suggest doing and how much? Let me know and we can compare what you were told to the shop manuals.
There are several possible reasons for the charging code and the mixture code so will see what the 4 digit code numbers might tell us. 96-97 were transition years when both types of codes could be read out, but you only have the OBD-I codes so far, so lets get the newer version. And also tell me about the operation/economy of the van at present which might be reflective of the codes.
Roland