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DRL/LOWBEAMS not working-2003 chevy cavalier


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acmahaffee
Novice

Mar 9, 2008, 4:24 PM

Post #1 of 11 (20111 views)
DRL/LOWBEAMS not working-2003 chevy cavalier Sign In

High beams and all other lights work but low beams and daytime running lights do not.Fuses all look good and the DRL relay has been replaced. Voltmeter shows power to all connections((different values though - 8V;11.7V;12.4V) at headlight assy even with light switch in off position. Is this normal? Any suggestions for further troubleshooting would be appreciated. With switch in low beam position, all wires show 11.9 V and in high beam position the pink wire drops to35 mv on left side and 0.6 V on the right side.

Thanks for your help
Chuck


Tom Greenleaf
Ultimate Carjunky / Moderator
Tom Greenleaf profile image

Mar 9, 2008, 5:01 PM

Post #2 of 11 (20105 views)
Re: DRL/LOWBEAMS not working-2003 chevy cavalier Sign In

Are DRL and low beam the same bulb? Could just be the bulbs??

T



acmahaffee
Novice

Mar 9, 2008, 11:32 PM

Post #3 of 11 (20102 views)
Re: DRL/LOWBEAMS not working-2003 chevy cavalier Sign In

In this system, one bulb serves all three functions - DRL;high and low beam headlights.
Chuck


Tom Greenleaf
Ultimate Carjunky / Moderator
Tom Greenleaf profile image

Mar 10, 2008, 3:25 AM

Post #4 of 11 (20100 views)
Re: DRL/LOWBEAMS not working-2003 chevy cavalier Sign In

I really don't understand what you were testing with the voltmeter. If there is power there for either the low beam or DRL then it's probaly just a separate filiment in the bulb that is the DRL and the low beam and both are burned out. Basically - I think the bulbs are blown!

Note: Ever see the expected hours of life on even household bulbs? Same with cars. Since DRLs are on the whole time the car is running they are going to burn out faster than without that feature. At the age of this car it's about time if all bulbs are orig. When a customer ever came in for a bulb on one side I always did both if they were known origs as I would tell them the other will be soon (usually within the week) if they didn't and that's been so since Grant took Richmond..........Wink Have you just looked at the bulbs for discolorization? Bet they look a bit too dark or silverish,

T



DanD
Veteran / Moderator
DanD profile image

Mar 10, 2008, 5:24 AM

Post #5 of 11 (20099 views)
Re: DRL/LOWBEAMS not working-2003 chevy cavalier Sign In

Hi
A couple of things to remember about this headlight system and they are; power is always present at the bulbs direct from the fuses. Next, the switch & DRL relay supply ground to the circuit.
With you saying that in low beam there is power on all wires, tells me that the bulbs are ok; power is passing through the bulb but not being used up because they are not getting ground.
In high beam; why you’re seeing a voltage drop at the pink wire is because they are being supplied a ground and the bulb filaments are using up that voltage; what you’re reading is the left over voltage.
DRL lights in this vehicle use the low beam filament at a reduced intensity by adding a resistor in series after the DRL relay to ground.
What I’ve found on a lot of Cavaliers is that the ground for that part of the circuit; anywhere from the headlights back to the fire wall corrodes and goes open for the low beam/DRL circuit.
If you look closely at the headlight connector you should be able to see letters (A,B,C) identifying the wires. You want to be tracing the A (blue) wires. Open up the harness and very carefully check that wire; you’ll find a splice somewhere close too or under the battery, where the left & right blue wires are connected together. They are a small gage wire so it takes very little corrosion before they go open.

Dan.

Canadian "EH"






Tom Greenleaf
Ultimate Carjunky / Moderator
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Mar 10, 2008, 7:30 AM

Post #6 of 11 (20096 views)
Re: DRL/LOWBEAMS not working-2003 chevy cavalier Sign In

Thank you Dan! Kitty and I were stuggling with that one! Good post for archives.........

T



acmahaffee
Novice

Mar 11, 2008, 11:47 AM

Post #7 of 11 (20078 views)
Re: DRL/LOWBEAMS not working-2003 chevy cavalier Sign In

Dan,
thanks for your help. I've traced the blue (A) wire back to where it goes under the battery and now have the front up on blocks but still cannot get my hands on the rest of the harness - I see it but can't reach it. Is there an easier way to get to it? I could take the wheel and splash guard off unless there is a better way? Please advise. Thanks again, Chuck

In Reply To


acmahaffee
Novice

Mar 11, 2008, 11:55 AM

Post #8 of 11 (20076 views)
Re: DRL/LOWBEAMS not working-2003 chevy cavalier Sign In

Tom,thanks for your help. The bulbs look good and no indication the filaments are broken. Also, I don't believe the bulbs would show resistance if the filaments were broken would they? I initially assumed the bulbs were not the problem because both went out at the same time; unless these are like the old Christmas tree lights that didn't seem likely. Ref: my post to Dan, I'm currently looking for a bad ground. Any advice on how to get to the harness underneath the battery? Thanks again,Chuck


DanD
Veteran / Moderator
DanD profile image

Mar 11, 2008, 12:21 PM

Post #9 of 11 (20075 views)
Re: DRL/LOWBEAMS not working-2003 chevy cavalier Sign In

No there’s no easy way to get to the harness and yes I’ve had to remove batteries, battery trays, wheels and inner fenders to gain access.
When you do find the open in the circuit and do the repairs, make sure you properly insulate your splice. The slightest amount of moisture that can get to the bared wires will cause the problem to come back, in no time flat. Shrink tube seems to be about the best that I’ve found; slide over the repair, heat it up and like its name, it’ll shrink nice and tight to the wire.
AC Delco has brought out a crimp on connector that has the shrink wrap already attached and it also has die-electric grease imbedded in the connector.

Dan.

Canadian "EH"






acmahaffee
Novice

Mar 11, 2008, 1:01 PM

Post #10 of 11 (20070 views)
Re: DRL/LOWBEAMS not working-2003 chevy cavalier Sign In

Looks like I have my work cut out for me. Thanks again. I'll let you know it turns out!
Chuck
I think I have some shrink tube around someplace - if not I'll pick some up. Not a job I'll want to do twice.


Creg
New User

Jan 23, 2009, 11:27 AM

Post #11 of 11 (19038 views)
Re: DRL/LOWBEAMS not working-2003 chevy cavalier Sign In

I joined just to tell you "THANK YOU" for the great info. After 6 hrs of laying under the dash I read your post, pulled the battery, opened the loom, and there it was!!! This car was an 2003 Impala, but same blue wire I bet.






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