Impala's headlights always on

[trouttrooper]

2000 Impala 3.8 Anyone have an idea on this little issue? I just had the tranny replaced and they cleared the service vehicle soon light, but low and behold it came right back on. Wife picked the car up so I didn't get to talk to the guy, but it's apparently a body code. Don't know what it is, but I did notice the other day that the actual headlights are on all the time when the key is on. I picked up on this when I noticed in the middle of the day I could dim the compass display light. Not seeing any other warning lights and plugging it in at Oreilly's didn't show any codes. I know I'll have to get a Tech 2 to scan the appropriate code, but was wondering if any of you had some suggestions.

Thanks.

 

[ak diesel driver]

does it have the auto position in the headlight switch?

 

[THEFERMANATOR]

All GM's since around 98 have had daytime running lights, so there supposed to be on whenever the key is on. Most will shut them off when you engage the parking brake, but some you have to cancel it with the headlight switch.

 

[WarWagon]

SES lights generally do not come on for body codes, trans codes, etc. They come on for emissions reasons. A slipping transmission or burned out speaker is no reason for you to fail emission tests. Most emission places check the SES light. So most codes stay hidden.

I would suggest loose gas cap, converter test failing on a long drive, fuel tank leak and you have low fuel so the vapor test isn't running - bad fuel gauge also can trip a light as the EVAP tests can't run with low fuel levels.

If you have a SES light and no codes, the computer memory power fuse or wire is bad, bad grounds during cranking etc. Something is clearing the computer memory of the code. Or the computer is bad and 'forgets' the code. The computer can work with bad memory - been there done that. Trips the light for a code and can't store it. Called it "Clinton" No memory and a big hard drive.

Junk on the dash covering the sensor for headlights?

 

[trouttrooper]

The light that tripped is not the SES, it's the Service Vehicle Soon light. There's no auto position on the headlight switch, it's of the era where the headlight switch is basically useless. This is something new that has occurred. I don't know exactly when this cropped up because the service vehicle soon light has been on for several months due to the tranny code. It's not running in DRL mode during the day, it's full headlight mode with taillights, marker lights etc. Nothing is covering the sensor. I suppose the sensor could be bad, but I didn't think those things went bad? Wife is leaving today with the Impala for her new job so I won't have the car back for several days. As long as this is the only issue I'm not too concerned. I'm crossing my fingers this isn't an indication of something major getting ready to fail.