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Daytime running lights

I HAVE A 1997 CHEVY BLAZER. THE DAYTIME RUNNING LIGHTS QUIT COMING ON AT ANY TIME. THE PARK BRAKE IS RETRACTING PROPERLY AND THE FOG LIGHTS ARE WORKING. EVERYTHING ELSE ELECTRICAL IS WORKING PROPERLY. FUSES ARE ALL OK.



I DON’T HAVE A MANUAL AND DON’T KNOW WHERE TO START.



ANY IDEAS?

I suggest you find a manual with a wiring diagram before trying anything else. It will help you track down the correct circuits that control the DRLs. Otherwise, your truly shooting in the dark.

However, I’m leaning towards a bad connector within the system or a bad relay. These are the weak links in most problems like this.

FIRST PLEAST TURN OFF THE ALL CAPS!

I suspect it is the parking brake switch. It it thinks the parking brake is on it will keep the lights off. It will also keep the cruse control form functioning. Try the cruse and see if it works. If not have the switch replaced. Other than that, follow Busted’s recommendation.

GUESS I’LL BE LOOKING FOR A MANUAL. CRUISE CONTROL STILL WORKS. IS THE RELAY ONE OF THOSE YOU CAN EXCHANGE (FOR TESTING ONLY) WITH AN ADJACENT RELAY?

HEY JOSEPH! I DON’T THINK HE HEARD YOU. Ha ha ha

I LIKE ALL CAPS. WHY WOULD THAT BOTHER YOU? DO YOU BELIEVE ALL THAT BULL THAT IT MEANS I AM SHOUTING? I SIMPLY THINK IT IS EASIER FOR PEOPLE TO READ. IT IS EASIER TO TYPE AND ELIMINATES A LOT OF EXTRA KEY STROKES.

ANY WAY, WHY WOULD THAT BE MORE IMPORTANT TO YOU THAN THE CONTENT OF MY QUESTION?

Actually, lowercase is generally easier to read. Caps=shouting has been a well accepted convention on the internet since the days when Usenet was big and the WWW was a pipe dream.

About the Blazer? I don’t have a clue, somebody who knows way more than me will be along to help.

Posting in all Caps is offensive. You don’t get to decide what everyone else is offended by…
And mixed case is easier to read. Again, you don’t get to decide…
You are asking for people’s help. We’re glad to help people. but good manners suggest you should be polite.

I CERTAINLY DIDN’T THINK MY INQUIRY AS TO WHY SOMEONE WOULD BE OFFENDED WAS IMPOLITE OR IN BAD MANNERS.

I DON’T KNOW THAT YOU EITHER HAVE THE RIGHT DECIDE WHAT OFFENDS EVERYBODY ELSE. I ASSUME YOU ARE SPEAKING OF YOURSELF WHEN YOU SAY “POSTING IN ALL CAPS IS OFFENSIVE”. I DON’T KNOW WHY IT SHOULD BE.

IF THIS IS ALL IT TAKES TO OFFEND YOU, YOU MAY BE SOMEWHAT SENSITIVE.

I DO APPRECIATE EVERYBODY’S HELP. I DO NOT THINK IT IS IMPOLITE OR OFFENSIVE TO TYPE THE WAY I DO. I CERTAINLY DIDN’T MEAN IT THAT WAY.

TREE HUGGER:

I CERTAINLY DIDN’T THINK MY INQUIRY AS TO WHY SOMEONE WOULD BE OFFENDED WAS IMPOLITE OR IN BAD MANNERS.

I DON’T KNOW THAT YOU, EITHER, HAVE THE RIGHT DECIDE WHAT OFFENDS EVERYBODY ELSE. I ASSUME YOU ARE SPEAKING OF YOURSELF WHEN YOU SAY “POSTING IN ALL CAPS IS OFFENSIVE”. I DON’T KNOW WHY IT SHOULD BE.

IF THIS IS ALL IT TAKES TO OFFEND YOU, YOU MAY BE SOMEWHAT SENSITIVE.

I DO APPRECIATE EVERYBODY’S HELP. I DO NOT THINK IT IS IMPOLITE OR OFFENSIVE TO TYPE THE WAY I DO. I CERTAINLY DIDN’T MEAN IT THAT WAY.

It’s not your inquiry that is impolite, it is your failure to follow basic “netiquitte” by using all caps.

Now, as to your original question: Are the DRL bulbs used for any other function (e.g. parking lights) and if so, do they still work in this alternate function? It seems that most of the GM vehicles I see on the road have one DRL light out, and it is possible that you simply have both bulbs burned out. I know, extremely simple stuff, but it is easy to overlook the obvious sometimes.

I believe the daytime running lights are a low current flow to the headlight low beams. I can’t really tell, because they are not working at all, now. But, as I remember, the single sealed beam was the daytime running lamp as well as the low/high beam. That makes me think there must be a resistor in the DRL circuit. I just don’t know where to look for the resistor. The low/high beams, parking lights, turn signals, and fog lamps all work properly. I checked three relays just below the windshield in the engine compartment, all are OK.

Any ideas?

Thanks

You cant fix your DLR’s until you understand how the circuit works.

You can’t understand how the circuit works without looking at the wiring diagram.

I have the factory wiring diagrams for all 3 of my Ford’s & for my wifes Sonata. As they say a picture/wiring diagram is worth a thousand words

This is why a simple little problem like DLR’s not working would be quickly & easily fixed on one of my cars.

BTW, the factory wiring diagrams for my 97 Explorer show the high beam indcator on the dash is wired thru the DRL module.

If I was having a problem with the DRLs on my Explorer the first thing I would check is to see if the high beam indicator comes on with the high beams…

Since yours “might” be wired the same, does your high beam indicator work?

Congrats on losing the all caps nonsense

The Haynes Repair Manual #38036 seems to have forgotten the 1997 Blazer; but the wiring diagrams for the Blazer are “pretty much” the same as the Haynes wiring diagrams for other 1997 Chevy trucks. The public library carries a Chilton’s based web site called ARRC (Auto Repair Reference Center) and alldata.com. Both sites have wiring diagrams. I just looked at the ARRC site (authorized by my library card) to compare (not a detailed comparison) to the Haynes Repair Manual covering other 1997 Chevy trucks. Thus, noting the near-match.

High beam indicator is working as is everyting else on this truck. The DLRs just didn’t come on one day. I park in a garage so I noticed when they became innoperative. They both quit at the same time. I guss I’ll have to make a trip to the library. Thanks.

Ditto, but this sure was entertaining to read!! :slight_smile:

i thought the running lights were selectable to turn on or off. i am not sure how it is done, maybe one of the other respondents have the info. I thought it was a fuse which you could pull, to turn off the drls?! to clarify; are you SURE you haven’t (somehow) turned them off? if you dont have a manual, are you sure?

BTW, I USE ALL SMALL, just to get to your point about CAPS!

1.Check if bulbs are burnt out. Probably not, but sometimes a filament can break and then later make contact with itself. Wouldn’t you be mad if you spent hours working on this problem and it was just bulbs?

  1. Determine that your drl’s are actually not working properly. Sounds nuts but sometimes you may think a feature is malfunctioning and it’s not. (I guess you’ve driven your vehicle for a while, so you’re probably correct that there is a problem.) Read everything in owner’s manual regarding the drl’s. Don’t laugh- it might be one of those, "Wow- no wonder they don’t work!- type of deals.

  2. Analize the symptoms displayed and write them down on paper, unless you have a real good short term memory. Again, this may sound illogical, but as you get enmeshed in the job, your mind can become “saturated” w/all the details of it.

4.You’ve gotta get some kind of wiring diagram- hellokit’s suggestion of the library having a program like alldata or whatever would be the best if possible. Spend time “getting to know” the diagrams, read up on what the various symbols mean, etc. Print out what you think will cover the problem and more.

4.Now, w/wiring diagrams as a guide, check the easy stuff first- fuses, relays, etc. Most relays are all in one place and many are identical to each other, so if you suspect a certain relay, you won’t have to go out and buy it.

5.If it’s not the easy stuff, you may want to get tracing paper and trace out just the parts of the diagrams that apply to the problem- it really simplifies things. Now spend time getting to know the relevant circuits to see if you can pinpoint the the culprit(s). May want to invest in a 12V test light. Connect clip to a known good ground, and you can check for available voltage w/probe.

Crank up your common sense and now you’re on your own.

No offense, but why wouldn’t you cooperate with 5 out of 6 people who were willing to help you save possibly hundreds of dollars?

One needs to know how something is supposed to work before one can know that it’s not working the way it’s supposed to. Clear? // From the Haynes, “The DRL system used on all models (Chevys), operates in two modes: daytime mode and nighttime mode. In the daytime mode, only the front turn signal lights are illuminated. In the nighttime mode, the headlights, taillights, parking lights, side marker lights and license plate lights are all illuminated, just as if the the headlight switch were turned ON. …The DRL system consists of the DRL module and the DRL ambient light sensor. …The DRL module uses the signal from the ambient light sensor to determine day or night mode operation.” /// Sometimes, you need more than pictures. // Conclusion: possibly faulty signal from the ambient light sensor, or, the DRL module is faulty.

It used to be that GM used the high beam filaments/bulbs in series for DRLs. This gives them an effective way to run them at lower level without an external resistor. There is/was a relay involved that switches between DRL and normal mode. I’d be looking for that relay. Well, actually I’d be looking for a wiring diagram first. This series deal also means if one high beam filament goes bad you lose the DRLs, but still have 1 high beam.

Hope this helps.