Dim Headlights, Check Engine Light On

Hello All: 2001 Cav
My check engine light has been on and off for the last few months. I went to my mechanic and he did a diagnostic test on it, said it was a faulty gas cap seal. I replaced the gas cap and the check engine light went off for a few weeks but came back. Recently, my headlights have been becoming more dim. I replaced the headlights and they're still dim. Any suggestions? I plan on changing fuses this weekend to see if that fixes it.

I hear that the headlight harnesses in these cars sometimes rub through, so check that. also check for corroded grounds and terminals. If all that checks out I'd take the battery and/or the alternator in to be checked, many parts stores can check them on the vehicle. Hope this helps.

I would say alternator as my first guess. They can create many gremlins within the electrical system when they start to go and can throw strange error codes. Have that checked first. Battery would be my second guess.

yea alternator, then battery

I probably should have mentioned that I'm like 3k over for an oil change. When I get it changed this weekend I'll ask the mechanic to check the alternator but the battery is only about 18 months old. Thanks everyone!

I had this problem a month ago.

Check to make sure you have the right headlights installed. I bought the 9006 model and my car really needed the 9007 model. It fixed that problem right away.

I had this problem a month ago.

Check to make sure you have the right headlights installed. I bought the 9006 model and my car really needed the 9007 model. It fixed that problem right away.

I have the 9007s installed but they're still pretty dim. I can see maybe 15 feet infront of my car with the regular lights, 25 with the bright.

u can check ur alternator pretty easily with a standard volt gauge just start the car turn as much electrical users on as u can (wipers lights radio)check between the battery terminals should get about 14vdc if its lower than 13vdc its probably the alternator if its good turn the car off and check the voltage again after turning every thing off u should stay at 12.5 or more

sounds like a wiring problem, check all your connections for corrosion, clean all that you find with vinager and a wool pad, be safe about it obviously, don't "cross clean", you know clean a live wire and the ground, could cause some burnage =P also check fuse under hood for corrosion.