I own a 2003 Dodge Ram and my voltage gauge has been running higher than normal and the lights dim when I turn on the Heat/AC. Can this be a bad alternator?

Also, I got a "no bus" error code in the odometer.

 

Any auto parts store can do a quick free test to see if it's the battery or alternator that's going out on you.

I don't know what it'd have to do with the odometer / data bus though.

 

it could possibly be dropping the voltage too low, which is affecting the PCM. just throwin' that out there....

 

It sounds likr your voltage regulator is going bad. That's an internal alternator part. That can cause overcharging, undercharging...etc...

 

Thanks for the help all. On my way to the auto parts store....will let you know what happened.

 

How did you make out? I seen an almost new alternator for $75 on ebay. They say it's a new pull off for a customer that upgraded. Lemme know and I'll find it if interested

 

Had the battery tested at an auto shop and they said its going bad. I swapped it out this morning and the gauge is still reading a little higher than normal.

I used my hypertech programmer to find error code P1687 which indicates that I have a faulty instrument panel or bad module. Could that cause the voltage gauge to read a little high?

 

I would think that other guages would be effected as well??

 

Before I take the truck to the dealer and spend 100 bucks on finding out if I have a faulty instrument panel...is there anything I can find on my own? Which fuses could be bad?

 

Check battery connections