GM Techs, help please

[Rexone]

1996 Suburban: Daytime headlights just stopped working. These are the ones that run slightly dimmer in daytime vs standard nighttime headlight use.
1. Is there an easy common fix for this problem, a relay or module that commonly fails?
2. Are there easy tests with a multimeter to determine wherein lies the problem?
Regular headlights with the switch work fine. Any help appreciated.

[pocketchange 22]

withiut sounding like a wize a$$ did you check the fuse. Under the hood

[IMPATIENT 1]

rex, there's a diode near the bottom center of your dash. it looks like a black amplifier heat sink with a 2 wire connector goin into it. unplug that connector and jump a paper clip across it, then check your drl's. if they come on, you need to replace that diode;) if the the paper clip test doesn't fix them, reconnect the diode, and look over towards the em brake racthet. there's a drl relay on that junction block on the fire wall. pull the relay out, look where 30 & 87 are on the relay, then use a paper clip across the corresponding terminals on the junction block(or just try another relay).
give me a call(580-326-8335 ask for tom) or pm tommorrow and i can send you the schematics.

[IMPATIENT 1]

ps, while doin the diode paper clip test , if the diode is the culprit, the paper clip will get reallly hot.becareful when removing it from the connector, it'll burn the shiat outta ya;)

[Kachina26]

I always just made sure the brights worked, then checked that the green DRL light on the dash was on. If all was good, new diode. Pretty rare that it was ever anything else. One time both high beam bulbs were burnt out. :mad:
When you get the diode Mike, remove it from the bracket it comes with and do the same with the one under the dash. Way easier than fiddling with that bolt that holds the bracket in place under the dash.

[JAY4SPEED]

rex, there's a diode near the bottom center of your dash. it looks like a black amplifier heat sink with a 2 wire connector goin into it. unplug that connector and jump a paper clip across it, then check your drl's. if they come on, you need to replace that diode;) if the the paper clip test doesn't fix them, reconnect the diode, and look over towards the em brake racthet. there's a drl relay on that junction block on the fire wall. pull the relay out, look where 30 & 87 are on the relay, then use a paper clip across the corresponding terminals on the junction block(or just try another relay).
give me a call(580-326-8335 ask for tom) or pm tommorrow and i can send you the schematics.
Ditto, good call Tom. DRL diodes were very prone to failure in that generation truck. We've changed hundreds of them over the years for DRL inop.
I always just made sure the brights worked, then checked that the green DRL light on the dash was on. If all was good, new diode. Pretty rare that it was ever anything else. One time both high beam bulbs were burnt out. :mad:
When you get the diode Mike, remove it from the bracket it comes with and do the same with the one under the dash. Way easier than fiddling with that bolt that holds the bracket in place under the dash.
Exactly, If you look at how the diode is mounted in its bracket, you can bend two of the tabs that hold the diode to the bracket and slide it out without having to unbolt the bracket which can be a pain in the ass. Just slide the new one in and rebend the tabs to where they were.
Jay

[Rexone]

Yes I've checked all light related fuses both under the hood and on the side of the dash by the door.
I will check this other stuff out tomorrow and report back. Thanks guys.
btw this model truck doesn't have a drl indicator light on the dash that I know of (unless it's been burned out since I've owned the truck)... possibly a later model addition... ?

[bonesfab]

Check the parking brake. If I remember correctly if you push the park brake down one click it will turn off the drl. just a thought.

[Rexone]

Rio, Does that cover 1996 model or later years? I have 2 96" and haven't noticed a dash indicator light on either truck. Bought one of them new.
96 model year as I remember (which may not be well) was the first year for drl's. And they later changed the system to where the headlights did not run dimmer than under normal night use (again someone who knows more than I about this please correct me if I'm wrong).

[Rexone]

Check the parking brake. If I remember correctly if you push the park brake down one click it will turn off the drl. just a thought.
I will definately check that, thanks

[Rexone]

Just went out and checked, that was not it. But thank you for the tip.

[Kachina26]

As far as I recall, they have always had the green DRL indicator.

[JAY4SPEED]

This has reminded me of something that happened me last year at the dealership. I've had a customer come in complaining that their headlamps were on and would not swtich to daytime running lights during the day. The truck was brought straight to me from the service lane. I had it back up there on the service lane in about 30 seconds. The customer was actually upset that I had it back on the service lane so quickly repaired. He accused me of not doing anything to fix the truck and that "I couldn't have possibly fixed anything that fast and that we were ripping him off." I had heard he was up there raising all hell with the service manager. I was called back up to the service lane to answer the customer's questions. I had to expalin to him that the paperwork he had on the dashboard was covering up the photocell and the truck always thought that it was night time. He didn't believe me, I threw the notebook he had on the dash over the photocell, showed him that the headlamps would stay on, then removed the notebook exposing the photocell to sunlight and a few seconds later, it switched to DRL. He grumbled something that resembled an apology under his breath and drove away. Goes to show you can't make some people happy, his truck was fixed in 30 seconds and for free at that, but he still wasn't happy. I guess you can't just win over everybody...
I'm pretty sure that Rex's DRL on his generation 'Burb wasn't one that operated off of a sunload sensor (photocell) but thought this was a funny story. Rex the little green light should be on whenever the truck is running and the headlamp switch is in the "off" mode.
Jay

[Rexone]

Good story.
Well I'm blind in one and can't see outta da other. I do have the little green drl indicatior light on the dash. I guess I just didn't realize what it was. :)
I haven't checked out the problem yet but will soon. Thanks,
Where is that photocell located Jay, just for shits n giggles.

[obnoxious001]

Where is that photocell located Jay, just for shits n giggles.
It's right under the map and stuff on your dash?

[Rexone]

It's right under the map and stuff on your dash?
No maps here ob, I just drive aimlessly until I find shit lol. I'm simi-concerned it may be under the empty chip bag and soda can pile tho.

[IMPATIENT 1]

its the diode rex;)

[JAY4SPEED]

Rex it was the next generation of trucks, tahoe, suburbans after yours that had the photocell. I do not believe yours works off of a photocell. But to answer your question, on later model years, its the little dome shaped thing near the center defrost opening and near the right side front speaker on S-10 models.
Like I1 says just change out the diode, you will be good to go.
Jay

[Rexone]

rex, there's a diode near the bottom center of your dash. it looks like a black amplifier heat sink with a 2 wire connector goin into it. unplug that connector and jump a paper clip across it, then check your drl's. if they come on, you need to replace that diode;) if the the paper clip test doesn't fix them, reconnect the diode, and look over towards the em brake racthet. there's a drl relay on that junction block on the fire wall. pull the relay out, look where 30 & 87 are on the relay, then use a paper clip across the corresponding terminals on the junction block(or just try another relay).
give me a call(580-326-8335 ask for tom) or pm tommorrow and i can send you the schematics.
The diode is the problem. Thank you all. :)