Driving lights arent working on 99 Tahoe

[99 Mob Mobile]

Hello, on my 1999 Tahoe my driving lights recently stopped working.. the green light is on but my lights arent.. Are they only supposed to come on when its in gear? i know on the 2000 and newer ones its set up like that but I'm not sure about the 99's..its the older style so it was the low beams that are the day time running lights... They used to always be on as soon didnt matter if you were in park or not like it does on the new style Tahoes.. not sure if it was already malfunctioned or not.. can someone fill me in if they are always supposed to be on when the key is turned on or are they supposed to come on when i put it in gear? Thanks for any info... but my problem right now is that they dont work at all.. my green light on the dash comes on when i turn the key on and start it but no lights..I checked the fuse and its fine and looked fora relay in the fuse box under the hood but i didnt find one...is there another place i didnt check? any info would be great

Thanks

[tgwright]

The DRL's should be on anytime the ignition is in the run position, the headlights are turned off, and the parking brake is off. Your problem could be one or more of several possibilities, but I'd try the DRL diode first. With age and use they get hot and just fail. There is a troubleshooting protocol in the shop manual that calls for testing the DRL relay, but from what I've read here, and personally experienced, the diode is most likely to fail first. Even when tested with an ohmeter or continuity light the diode may test good but in fact be unable to handle the DRL current.

[777stickman]

Welcome to the forum. Just for clarity they are called "daytime running lamps" or DRL's. The system is a bit complicated but I'll try to asnwer some of your ?'s. First thing is anytime the green light is on the DRL's should be on. When you turn the key to run the light should come on. When you turn on the headlights or engage the park brake the green light should go off. The fuse is at the left side instrument panel. DRL/FOG 20a #15. Power runs to this fuse "at all times". There is a relay located in the convenience center behind the park brake pedal. It's in the bottom middle position. 1st thing to do is pull it out and check for 12v at the upper right socket. This will check for power coming from the fuse thru the diode to the relay. Don't need to turn the key on to check this. Let us know...........Steve