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2004 chevy trailblazer_ls
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19 Posts
Discussion Starter #1
i have an intermittent failure of my low beam headlites. They simple shut off. The high beams still work. after a variable amount of time for 15 mins to overnite the low beams work. anybody?? i hate electrical problems.
 

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2004 gmc envoy_slt
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2,203 Posts
It is probably the Low Beam Relay #46 in the underhood fuse box. Try swapping it with #45 for testing purposes. When replacing this "relay", be sure to buy an OEM name brand such as AC Delco.
 

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2008 isuzu ascender
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975 Posts
Agreed , replace relay, common item on this car . Was a recall item on the 2007-2008 years .
 

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2005 gmc envoy_sle
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228 Posts
its not the relay - you will get the same issue happening again - from what I can find there is no solid fix for this issue. I have done the relay swap - no help - mine still occasionally flickers and sometimes goes out completely for a short period of time. I have learned to live with it.
 

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8 Posts
It's a known problem with the HDM (Headlight Driver Module), in normal speak, the headlight relay. There is a recent recall (circa 2016), but for TBs, the recall is only good for 2006 & 2007. The description states as follows:

"General Motors has decided that a defect which relates to motor vehicle safety exists in certain 2005 – 2009 model year Buick LaCrosse (Allure) vehicles; certain 2006 – 2008 Saab 9-7x vehicles; certain 2006 – 2007 Buick Rainier, Chevrolet Trailblazer and GMC Envoy vehicles; certain 2007 Pontiac Grand Prix vehicles and certain 2006 Chevrolet Trailblazer Ext and GMC Envoy XL vehicles. The headlamp driver module (HDM) may not operate properly in the thermal environment of the underhood electrical center. If the HDM is not operating correctly, the low-beam headlamps and daytime running lamps could fail to illuminate. This failure could be intermittent or permanent. This condition does not affect the high-beam headlamps, marker lamps, turn signals, or fog lamps. Loss of low-beam headlamps, when they are required, could reduce the driver’s visibility, increasing the risk of a crash."

The fix is to replace the relay with 13506836. It's a little pricey for what it is - about $30ish bucks if you have to pay out of pocket.
 

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2009 gmc envoy_slt
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3 Posts
Had same issue on '09 Envoy. Recall was for '07-'08 models. Replaced with new module from autozone for $30. Went to local GM dealer and told service dept that problem still exists on newer models. They ran my VIN and found mine was covered too and replaced with redesigned module (cost over $100) for free. Even copied my autozone receipt and sent me check a couple weeks later.
 

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2004 gmc envoy_slt_xl
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66 Posts
What vehicle do you have? if you have a Saab 9 7x with the HID headlights it could be A bad ballast also. I have a 2005 9 7x with the HIDs and I had so many problems with the ballast and the bulbs that I bought halogen housings and replace them, I have not had any problems ever since
 
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