nighthawk2207 Posted May 21, 2009 Report Share Posted May 21, 2009 Does the ecu on our trucks have the ability to detect if an alternator is bad? My check engine light came on an then i noticed the battery light started coming on an going off randomly... Quote Link to comment Share on other sites More sharing options...
Fireman31 Posted May 21, 2009 Report Share Posted May 21, 2009 While the battery light signifies an issue with the charging system, the CEL is probably unrelated. You really need to get it scanned to see what is happening, most auto part stores like Advance, AutoZone, and O'Riellys do it for free...... Quote Link to comment Share on other sites More sharing options...
mcmahan Posted May 21, 2009 Report Share Posted May 21, 2009 good luck. get it scanned and post up the code Quote Link to comment Share on other sites More sharing options...
nighthawk2207 Posted May 26, 2009 Author Report Share Posted May 26, 2009 I got it scanned an the guy said it was prolly the gas cap but it came back on i wana say the code was p440 or something. it said emission control air vent cir. i will have to get it rescanned unless someone can see what code matches the description i gave Quote Link to comment Share on other sites More sharing options...
Doughty08 Posted May 26, 2009 Report Share Posted May 26, 2009 My alternator went out and the check engine lights did not come on it just told me that the batt. wasnt charging and the brake booster needed to be serviced. But the Batt. light did come on Quote Link to comment Share on other sites More sharing options...
Fireman31 Posted May 26, 2009 Report Share Posted May 26, 2009 I got it scanned an the guy said it was prolly the gas cap but it came back on i wana say the code was p440 or something. it said emission control air vent cir. i will have to get it rescanned unless someone can see what code matches the description i gave Was it a P0445 or 449? One of those two is the gas cap, you need to remove the cap and retighten it. That is a common occurence with most late model GM vehicles when the gas cap is not tightened enough after refueling. It can take a few days for the light to go back out....... Quote Link to comment Share on other sites More sharing options...
nighthawk2207 Posted May 27, 2009 Author Report Share Posted May 27, 2009 Was it a P0445 or 449? One of those two is the gas cap, you need to remove the cap and retighten it. That is a common occurence with most late model GM vehicles when the gas cap is not tightened enough after refueling. It can take a few days for the light to go back out....... I did that an it came back on acouple days later, can a gas cap be bad? because the guy said it was the gas cap, but to make sure i will get it scanned in the morning an right the code down before he asks me if i want to clear it or not. Quote Link to comment Share on other sites More sharing options...
benjaminh2 Posted May 27, 2009 Report Share Posted May 27, 2009 it could be a bad gas cap, more than likely it needs a evap vent soleniod. the solenoid sticks partially open mimiking a leaky gas cap. it would have to smoke tested at a dealership or qualified repair garage to know for sure though. Quote Link to comment Share on other sites More sharing options...
nighthawk2207 Posted May 28, 2009 Author Report Share Posted May 28, 2009 ok I was guna get it re-read but after i retightened my gas cap it went off i will keep an eye on it but i'm starting to think it really was the gas cap i might buy another one just for the heck of it. it can't be that expensive Quote Link to comment Share on other sites More sharing options...
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