I have an '06 w/108k miles and tonight is the first time I've seen the check engine light stay on (bought it at 70k). I had at least one battery dead enough where it would just crank twice and then go to a series of clicks. I found some gunk built up around the + terminal and connection so cleaned that out and put the charger on the battery while still in the truck. After about an hour, it started but now my check engine light remains lit. All gauges are in the normal range.

Full disclosure: I may have cranked it over longer than I should have while hooked up to the charger after only the first few minutes of charging. I kept turning over just enough to give a guy hope. I hope that wasn't enough to jack anything up.

More full disclosure, had the pos and neg clamps mixed up the first time I fired up the charger. The charger was live for about 30 seconds like that. The cranking described above was not done when I had the clamps mixed up.

So here I sit in my dunce cap wondering if I screwed up my truck and if it will take me on my 400 mile road trip tomorrow a.m.?

I should be able to get somewhere at my destination to pull the codes, but my plan was to hit the road in the wee a.m. hours.

Any ideas? Thanks in advance.

 

From my experience, the check engine light comes on due to low voltage, and stays lit until you have a dealer clear the code, or you clear it yourself with a programmer.

I used the Smarty JR to clear the code after I had similar issues with a bad connection between the two batteries. Prior to clearing the code, I drove it for quite a while without any problems. I wouldn't worry about the light ruining your trip if you've tested good voltage at all places (with lights AND while cranking). I have an '06 Mega Cab BTW.

 

I just had this problem and posted it on this forum. My truck had set eactly 6 weeks. It does set for weeks at a time, however, not usually more than 4. It started right up, but the check engine light was on. It went off after I had driven the truck about 10-12 miles and turned it off. Once restarted, it's been off since.
BUT, now its the radio! Nearly every other time the truck is started, the radio does not work. Do you ave this issue, too? There is a StarScan for this that the dealer can do. pcm

 

Just had 2 replace batteries in my 06', wouldn't start when i went to leave work last week. Cranked over a few times and then click,click,click. Got jumped off and drove to Autozone with check engine light on the entire way, about 20 miles. Bought 2 new Duralast Gold batteries, installed them in the parking lot. Drove home, 1.5 miles with check engine light still on. Hooked up the Smarty, cleared the code.. P2509 if memory serves me correctly-- I wouldn't lay any bank on it-- been fine since.

I didn't hook any leads up backwards or anything, but if your not seeing immediate ill effects from doing so your probably OK. I'd be for replacing batteries or at least prying the caps off and topping the cells off with distilled water but I dought you "screwed your truck up"

 

Made it here, seems to be holding a charge just fine. Light went out somewhere between 200-300 miles. Thanks all. I probably will be in the market for new batteries, just to be safe. And a better work light to tell red from black more easily...

 

Just after I bought my 2006 this summer. It cranked over slow but finally caught and started up. The engine check stayed on. Did that for three or four starts then when out. I am having to agree that it had something to do with low voltage in the system.