I tried to tag this on to the end of the fuel pump thread I had, but I didn't get any responses, so I'm going to try a new thread. When I got my truck 2 years ago, the cel would come on once and a while and I would get code 41 (generator field). Then it stopped happening for about a year, then it started acting up again. Then it stopped for another long while, and recently it has been happening again. It doesn't occur with any consistency, however when it does it is usually within a short time after starting the motor. If it does happen, I can turn the engine off, and turn it back off and the cel goes off and everything is normal. I tested the battery with a multi-meter, without the engine running the battery is at 12.6V, with the engine running it is at 14.5V. However, sometimes i fire the motor up, and there is a lot of fluctuation, it ranges from 11.3V to 14.9V, it only lasts for about 1 or 2 seconds, then evens out at 14.5V and stays there. Right after the fluctuation the cel is thrown. It seems weird how it would happen, then stop for such a long time then pick up again. It happened with the old 318, and the 360 I have now, given it is the same alternator (Its only 3ish years old) and computer. Along with all that, my last tank of gas I took a huge mileage drop. I went from averaging 10mpg down to 6mpg, with no difference in driving style or environment. My goal is to get a few miles on this tank, then fill up again and check the mileage. I am starting to think, I may have a problem with the computer and or the regulator. Not really sure where to go next, any help is appreciated

 

No responses, Today my dads truck stopped charging, so I let him use mine and got a ride to school with a friend. However while my dad was driving home my truck stopped charging. Now the only 4wd vehicle we have left is my moms Jeep, and we are in the middle of a huge snow storm. You guys gotta have some ideas

 

I talked to my instructor about your issue today in class (he works for Chrysler) he said he would research it when he goes to work on Saturday... if you can hold on till Monday I might have something

 

another thing... is there any tsb's about it? usually they can give you the answer to your problems

 

Thanks a ton, I took the alternator into Orielly's and got it bench tested, it checked out. It may be the voltage regulator possibly. Still not sure about the terrible mileage drop, seems like its running rich.
And there are no tsb's that I know about

 

it is possible that the charging issue and milage are related. it should charge at slightly less than 14v if it is at 14 it is possible that some where their is high resistance and the pcm/regulator is seeing less voltage than what the alternator is putting out so it is commanding full charging and that puts a larger load on the engine than normal causing your lower milage. also milage and batteries suffer in the cold. the battery voltage may be normal but it may not be able to sustain a load. the battery needs to be load tested normally Orielly's does not have a load tester but simply a voltage tester but you should ask if they can load test a battery.

 

It could be the cold, Last winter It got about 9mpg, however last year was warmer. This year we have had many days below the -30 degree mark, and that could very well do it. I thought Oriellys load tested it. The bench tested it, but that doesn't mean it was load tested, Do know an autoparts store that load tests? The battery voltage is low, The tester at Orielly showed it was putting out 14.9V max, but it could be lacking on the amps its putting out. The alternator was only putting out 11.6 on the truck though, so I was going to try a new voltage regulator.

 

well the colder it is the more fuel its gonna take seeing how the air is more dense.. and since your truck is fuel injected... its got an air sensor of some sort so if its registering really cold air its gonna dump fuel to compensate... my mom has a jeep commander and if it drops below 43 degrees it drops 3mpg instantly... 44 degrees its got 16mpg 42 its got 13mpg... all because the ambient air tmp senor thinks its too cold and dumps the fuel in there

 

so looking at a different PCM, one that is for the 360 5.9L manual 4 speed. Truck had an a/t with a 318. is the wiring harness the same for both PCMs? meaning, if i put a different PCM on will I need a different harness?

 

For the same year yets they are the same wiring\connectors. The difference is in the programming.