[&o]hi this is a great place.I have a problem with my 1982 Dodge 400 convertible.
This is an electrical problem I think. my battery light comes on when driving if I turn on the lights or radio.I had the alt and volt reg checked and they are fine. and the battery checks out. I dont know what else to check out for a problem like this. does anyone have any suggestions.all will be greatly welcomed.

 

Well that is no good. Hate to say it but the 82 400's were a breed there own. You didnt mention if you had the mitsu 2.6 or the dodge made 2.2 and if you could tell if its the dodge alt or the bosch. But here are some things to try. They call them idiot lights for a reason, sometimes the idiot just comes on. If you had the alt and reg and bat checked out and your shop gave them the ok i would do the driveway test. crank the car up and turn on every electric load you can, i mean the lights on hi beam the blower motor a/c( if it works) hold your foot on the brake, work the power windows, put the top up and down turn the radio on use the cig lighter etc. The first thing you shouldnotice is an increase in engine speed as it compensates for the alt load. The alt and reg is complety seperate form the computer used in the 82 thru 84 cars all it looks for is voltage at a preset number between a given engine rpm range. However it does monitor engine rpm, hence when the alt load pulls the engine down it compensates for this so you can hear the engine rev up a few hundred rpms while its idleing. If it does all of this but the light still comes on i would start turning stuff off till the light goes off and check that circuit for problems. if you find nothing wrong with the circuit no shorts or anything i would suspect that the problem is the alt and or the reg as with the load applied it does not keep the voltage with in the spec range and the computer trips the bat light. Now it is not certain but possible your problem is the computer its self, however the 82 thru 84 computer is a simple binary computer ancient if you like there is a chance that it is not seeing the right voltage even though it is there and tripping the idiot light. All these computers did was monitor the ignition spark, engine rpm,( it still has the carb so it can only compensatethat a bit)o2 sensor, choke, fast idle selonoid, out side airtemp, engine knock sensor, engine water temp and the output of the alt. I would think that there is something wrong with the alt and reg and bat depending on the age and would start with a new reg, if it still does it i would replace the bat and if it still does it i would replace the alt and last the computer its self. I owned a maroon 82 400 convt and had problems with everything but the electrical system, so much i almost made it my last chrysler madevehicle. They were sadly probaly the worst cars,drive train wise.dodge ever turned out even with the 2.6 mitsu motor it was nothing to write home about. Another thing to check is the headlight switch. they do go bad and can overdraw and cause a bat light to come on. since you said it does it when the light and radio is onAnd for your info they made a total of 31,449 Dodge 400 for model year 1982, sorry dont have the break down think the convertible number was around 8,500 or so. So its definatly a keeper if you can keep it going. You know this was the first convertible made by dodge since the 71 challenger, and the first domestic convertible since 76 so in a way its a rare car, as much as i hated the 400 i had i still had lots of fun in that car but i liked the 86 600 i traded it in on way better.

 

Thanks for all the info,it is the volt reg. we had it change and now it is working fine. the first guy who checked it I guess didnt know what he was doing. I think this is worth fixing up. it has a great body all orginal carpet which is in great shape and the car drives very smooth.this was kept in a garage after the top got torn and was not driven much. it has seventy thousand orig. miles on it so for an 82 that is great.my truck has 59000 and its a 2000. when I finally get the whole thing done I will post a pic. again thanks for the info.