I have an early 04 ram. The check engine light goes on and off by itself. Dealer says there is no stored codes. How do I run a key test to check my own fault codes ?? I heard a battery temp sensor has been throwing sparatic errors for some. Once I read the code is there a list to decipher what it means ?? I probably need a service manual. Anybody cheaper than Geno's at $87 for one ??

 

Turn the key to the run position on and off three times. The third time, the odo window will produce the code number like P0193 and then go back to the odo. If your truck isn't storing any codes then it will just say the word "done" and then go back to odo display.

 

If check eng. lite goes out then its called a soft code - lite comes on only when there is a problum that comes & goes , dif. form hard code permanant failure of some system .
You can find code def. here - tech facts top of page , OBD ect. - not all codes are there .
The key turning also will not show all codes , need scanner , dealer did not know how to use theres [ should not be news ]
The Genos is a factory shop manual - best way to go , any after market is a waste of $$$ if you realy want to know your trucki , and the price is good unless you can find a used one.

 

This has been a very prevelant problem....chaffing wire down by the air conditioning compressor:
https://www.dieseltruckresource.com/...ad.php?t=81936

But to answer your question....go to http://www.hemitruckclub.com and they have 2003-2006 shop manuals online for free.

Be sure and leave the key on at the end of the on/off/on/off/on trick to read the codes.