P1491 on a 2002 Ram 1500 with 4.7 L engine. What is the most likely culprit?

 

It's the condenser fan relay circuit. Probably just the fuse is blown and I'll bet I know why. Do you live where the winters are cold?

BTW: It's fuse #39 and it's a 25a... Be sure to reset the PCM to make the code go bye-bye after you replace the fuse...

If this does not fix the problem or the problem returns, do a search for TSB 08-015-02, it means water got in the fan assembly and popped the fuse, most likely it froze and prevented the fan from turning and the fuse blew. If the water rusted out or caused damage to the assembly, you need to have the steps in the TSB performed.

Odds are though, the fuse will fix it...

 

Isnt there a way to check your code turning your truck on and off like 6 times or something?

++EDIT++
Nevermind I found it an old er post, I used search... sorry

 

There is a thread in the FAQ section with the codes and their meanings...

 

its 3 times key to run then off. and that happened to me last week. the fuse didn't fix it at first and i had the computer cleared still came back. went to go investigate it more and the code went away. just needed the new fuse