DRL's problem

Hi,

My 2000 Z71 (OBS) DRL's no longer function. I have searched the forum about this problem, and found things to check.
#15 fuse is good. My fog lights also work.

I have tested the DRL relay under the dash and have power going to the upper right terminal with the vehicle off. I also have power going to the upper left terminal with vehicle running. None of the other terminal have power going to them.

I also test the DRL Diode and has power going to both the orange and yellow wire connections.

My DRL light on the instrument cluster is on. My e-brake is not set as I use it quite often.

I do not know what all this points to and was wandering if anyone had any insight on what it may be.

Thanks,
Jamie

My '99 LT (I believe the same as your 2000 Z-71) turned out to be a diode failure. The diode tested good, showed voltages passing through as it should, but it wouldn't conduct the current necessary to light the lights. After everything else checked OK, I replaced the diode because I knew that it was not fully testable with an ordinary voltmeter, and by default, that had to be the one thing that was causing the problem. Turned out I was right. When I replaced the diode, I disassembled the old one, just a natural curiosity of mine, and the material inside just crumbled. Obviously it had been cooked from all the heat over the years.

My '99 LT (I believe the same as your 2000 Z-71) turned out to be a diode failure. The diode tested good, showed voltages passing through as it should, but it wouldn't conduct the current necessary to light the lights. After everything else checked OK, I replaced the diode because I knew that it was not fully testable with an ordinary voltmeter, and by default, that had to be the one thing that was causing the problem. Turned out I was right. When I replaced the diode, I disassembled the old one, just a natural curiosity of mine, and the material inside just crumbled. Obviously it had been cooked from all the heat over the years.


Do you remember what your DRL diode was carrying on the current? Mine is at 11.xx +. What did the diode cost you? Did you get it at the dealer or auto parts store? I have looked on a couple different autoparts sites and can't find this particular diode.

I don't have any idea what the current was. The voltage was probably normally less than 12, but I don't know. Mine (not necessarily same as your's) took diode part number 15043231, which GMPartsdirect has for about $19. Understand that with a good load, a failing diode may pass 12 volts but won't carry the necessarily current to light the lights. If your dash light is on the DRL module is probably good, as is the relay, probably.

Since you didn't say it, I just have to ask... did you check the bulbs or just figure they wouldn't both burn out at the same time?

Now THAT'S a good question. In my case I knew the headlight low beams were the same filament as the DRL's, so that quickly eliminated that possibility, but colaz71 didn't say anything about that. I hope his low beams are working.

My low/high beams work with my manual switch on both d/s and p/s. They just don't turn on automatically. My DRL's have not worked for about 6 months and I am just now trying to fix them. Sorry about that.

Several ?'s

1. You say your 2000 is an OBS (Old Body Style)?
2. OBS DRL's use the same bulb as the regular low beam headlights? Not separate DRL's.
3. Does the dash DRL light go out when you apply the parking brake or turn the headlights on? This has to happen with the key in the "run" position.
4. For me, what did you mean by d/s & p/s????

"tgwright" gave you a good heads up about the diode being able to conduct voltage but not current. So pull the diode and jumper the 2 wires and see what happens.

PLEASE post back what you find 'cause this forum is a learning tool for all.

Several ?'s

1. You say your 2000 is an OBS (Old Body Style)?
2. OBS DRL's use the same bulb as the regular low beam headlights? Not separate DRL's.
3. Does the dash DRL light go out when you apply the parking brake or turn the headlights on? This has to happen with the key in the "run" position.
4. For me, what did you mean by d/s & p/s????

"tgwright" gave you a good heads up about the diode being able to conduct voltage but not current. So pull the diode and jumper the 2 wires and see what happens.

PLEASE post back what you find 'cause this forum is a learning tool for all.



1.) Yes my 2000 is the old body style.
2.) I was thinking they used the same bulb as my low beams.
3.) Yes when I press my parking brake or turn on my headlights with it running. My DRL instrument light turns off.
4.)driverside and passengerside lights

I am going to try to jump the diode wires tomorrow. I work seconds so I get off work late, and my 13 month old daughter is a hand full.(In a good way though)

So pull the diode and jumper the 2 wires and see what happens.
Good advice.

Here is a tip on replacing the module:
http://i83.photobucket.com/albums/j295/NoEcm/DRLDiodeReplacement.jpg

Thanks for the link NoEcm. Well I jumped the wires on the DRL diode and voila. DRL's kicked on. Now just have to order the part. Same as Tgwright '99 LT. Called GM to double check though.

Thanks for everyones help.

Thank you for posting back and thanks to "tgwright" for the heads up on the diode. A great lesson.

I recieved the DRL diode today and put it together. Everything seemed to be working fine. When it hit dusk though. It would not kick on my instrument cluster lights or allow me to use my brights. Not sure if it allowed me to do that before, but I thought it did. It has been so long since they worked though. I have to manually turn on my lights for instrument cluster lights and brights to function properly.

Is there even a problem or are they suppose to work like this? Just can't remember.

I recieved the DRL diode today and put it together. Everything seemed to be working fine. When it hit dusk though. It would not kick on my instrument cluster lights or allow me to use my brights. Not sure if it allowed me to do that before, but I thought it did. It has been so long since they worked though. I have to manually turn on my lights for instrument cluster lights and brights to function properly.

Is there even a problem or are they suppose to work like this? Just can't remember.

For the intrument panel lights to work and be adjustable the light sw has to be in the park or headlamp position. For the high/low beams to work the sw has to be in headlamp position.

So, I don't see a problem unless your '00 OBS has some different elcetronics.

I recieved the DRL diode today and put it together. Everything seemed to be working fine. When it hit dusk though. It would not kick on my instrument cluster lights or allow me to use my brights. Not sure if it allowed me to do that before, but I thought it did. It has been so long since they worked though. I have to manually turn on my lights for instrument cluster lights and brights to function properly.

Is there even a problem or are they suppose to work like this? Just can't remember.

You have to manually turn on your lights for the instruments lights and the "brights" work.

There is not much difference between the DRL's and your low beams, just a smidgen of diffference. Here's how you can check the difference:

Park somewhere dark. Release parking brake and turn on headlights (the low beams are now on). Turn off headlights (this switches the lights to the DRL's). You'll notice that there is not much difference in brightness.

Thanks everyone. I just couldn't remember whether the lights switched over to night mode like on our Bonneville and a '96 Beretta I use to have. It's just been so long since the DRL's on my Tahoe were working.