2008 1500 Silverado LoBeam Headlights browned out then burned out simu

JakeKohl · December 16, 2014

I have a 2008 Silverado 1500 LT with a low beam headlight problem. I have a set of Recon Halo headlights that uses the factory wiring harness for the hi/lo beams and turn indicators and they use a standard H1 type bulb. I wired the halos and the twinkle lights with their own power and they're completely separate from the headlamp circuits.

This past weekend (while 1,000 miles from home, naturally) I started the truck at night to drive a short distance away and noticed that both low beam headlights were VERY dim. I inspected from the front and both of them were of equal brightness and as if they were browned out. I used the fog lights to get where I was going and stopped for gas along the way. At that point, the driver's side bulb (that was less than 3 months old) was completely dark while the passenger's side bulb remained dimly lit. By the time I arrived at my destination, the passenger's side low beam light was also completely dark. High beams and fog lights continue to function normally (as do turn indicators, halos, and twinkle lights).

Needing the lights to tow my boat and drive back home, I spent some time trying to troubleshoot the problem. The fuses are fine (each fuse for each headlamp), I swapped relays around to see if maybe the relay was bad. I removed the grill and tried to trace the ground wire but never could figure out where it terminates (but I assume that it is shared with the high beams?). I removed the bulbs from the headlight assemblies and discovered they were burned out. I stopped on my way out of town to replace them and the same thing happened again.

It sounds to me like a ground issue but I would be a little surprised that the hi beam and low beams would have a separate grounding point.

I recently installed a new driver's side front engine mount (and did so without removing the front drive axle) so I was contorting things in the area around the main power distribution block several months ago. Is it possible that I damaged some wiring in that area? Where would you start to look for the problem?

Doug_Scott · December 16, 2014

Don't count on the in-dash gauge readings to be accurate enough to debug something. Get a voltmeter (or a multi-meter) and connect direct to battery positive and chassis/engine ground.

Keep in mind that a voltmeter is actually measuring voltage differential. This is something that is important to understand when using a voltmeter to test circuits. You can test for bad connections by connecting a voltmeter on either side of the connector. Use a digital meter, and set voltage scale to 2v when testing volt drop across a connector. A connection should not have a reading of more than one tenth of a volt. Polarity is not really important, if leads are connected backwards on VOLT setting, you will get a negative value. No damage will occur provided you are set to voltage, and leads are connected to voltage ports on meter, if equipped with multiple ports for lead connection.

Doug_Scott · December 29, 2014

Thanks for the feedback. I finally found the problem. I found a fitters manual that showed that the left and right headlight assemblies have their own grounds so it was very unlikely to be an issue with the ground. After taking the front end apart (including removing the bumper), I finally found a pinched wire on the hot lead to the driver's side headlight. Apparently it was shorting out enough to drop the voltage coming through the headlight relay (causing both to go dim) but not enough to blow the 20amp fuse for that headlight. The thing that stumped me, was that, apparently, the low voltage operation in that semi-shorted condition was enough to blow both headlight bulbs. I wouldn't have thought that would have happened but it seems to be the case.

I also discovered that the Recon supplied wiring harnesses that plugs into the factory harness is of really poor quality. Where their wires enter the back of the plug it's completely open and not sealed. Added to which, the wires are not captured well in the back of the plug and you can pull on them and disengage the blade inside the plugged connection. I also found that one of these was barely making contact inside the plug and had some corrosion on the connection (I've only had these headlights for 6 mo). I sealed all of that up, put contact grease on the plug terminals, installed two new headlight bulbs, replaced the pinched wire, and it's been working great for a week.

The pinched wire won't be the cause of your issue. Does not matter if less than 1mm of wire is shorted out, it will blow any fuse you have up to the max amp that the wiring can take before melting the wire.

You likely found the issue, and corrected it, without even knowing you did. Really sounds like it was a bad connection somewhere that once you unplugged everything and connected them again the issue was resolved for now. From your description of the connectors, you should expect to have connection issues in the future. You may want to replace all the connectors in that kit with connectors like OEM uses, likely Delphi in this case.

Zebrafive · December 29, 2014

Thanks for the feedback. I finally found the problem. I found a fitters manual that showed that the left and right headlight assemblies have their own grounds so it was very unlikely to be an issue with the ground. After taking the front end apart (including removing the bumper), I finally found a pinched wire on the hot lead to the driver's side headlight. Apparently it was shorting out enough to drop the voltage coming through the headlight relay (causing both to go dim) but not enough to blow the 20amp fuse for that headlight. The thing that stumped me, was that, apparently, the low voltage operation in that semi-shorted condition was enough to blow both headlight bulbs. I wouldn't have thought that would have happened but it seems to be the case.

I also discovered that the Recon supplied wiring harnesses that plugs into the factory harness is of really poor quality. Where their wires enter the back of the plug it's completely open and not sealed. Added to which, the wires are not captured well in the back of the plug and you can pull on them and disengage the blade inside the plugged connection. I also found that one of these was barely making contact inside the plug and had some corrosion on the connection (I've only had these headlights for 6 mo). I sealed all of that up, put contact grease on the plug terminals, installed two new headlight bulbs, replaced the pinched wire, and it's been working great for a week.

Were your factory headlight harness connectors sealed on the wire side?

Did your factory connectors have a terminal lock (gray) that snapped to the wire side of the connector?

I think the only seal is a blue seal for the connector bodies.

I would consider replacing the Recon connectors with Delphi connectors.

Carder09 · December 16, 2014

If you think it's a grounding issue, which your high beams work so it seems they could be separate, strip a small middle section of the grounding wire and solder in, and heat shrink or wrap, a new ground wire to a good earth point. That will tell you if your ground was/is the issue. That or you can probably shoot both your positive wire and then ground to make sure you are receiving the correct voltage and getting low resistance on your ground.

JakeKohl · December 16, 2014

If you think it's a grounding issue, which your high beams work so it seems they could be separate, strip a small middle section of the grounding wire and solder in, and heat shrink or wrap, a new ground wire to a good earth point. That will tell you if your ground was/is the issue. That or you can probably shoot both your positive wire and then ground to make sure you are receiving the correct voltage and getting low resistance on your ground.

Thanks for the suggestions. Running a second ground wire is probably my next step when I get the time (which I'm short of at the moment...this will involve removing the front bumper to get the headlights out because the Recon units are slightly larger than the factory units and I can't get them out with the bumper end-cap in the way). I would really like to shoot the voltage steps but since the $18 bulbs burn out in a matter of minutes, this isn't a great option...but that does give me an idea; I suppose I could temporarily connect a cheaper turn signal bulb or something to do the tests with. I have a bunch of those laying around.

I'm hoping someone knows how the grounds are routed from the hi-beam / low-beam circuits and where they terminate so I can check that termination first (assuming they are separate).

Also....will a halogen bulb blow because of a ground problem?

Carder09 · December 16, 2014

Grounding shouldn't cause your bulb to blow but a short would. That's why when you were saying your bulbs were dimming I was thinking maybe a high resistant ground wire somewhere i.e. A ground with very few strands or a lot of heat but usually heat isn't the issue.

Carder09 · December 17, 2014

Don't count on the in-dash gauge readings to be accurate enough to debug something. Get a voltmeter (or a multi-meter) and connect direct to battery positive and chassis/engine ground.

Keep in mind that a voltmeter is actually measuring voltage differential. This is something that is important to understand when using a voltmeter to test circuits. You can test for bad connections by connecting a voltmeter on either side of the connector. Use a digital meter, and set voltage scale to 2v when testing volt drop across a connector. A connection should not have a reading of more than one tenth of a volt. Polarity is not really important, if leads are connected backwards on VOLT setting, you will get a negative value. No damage will occur provided you are set to voltage, and leads are connected to voltage ports on meter, if equipped with multiple ports for lead connection.

This, or if you have a load lamp lol

Options. ☺

JakeKohl · December 31, 2014

I do understand and I have some qualifications to make this assessment. I'll be quick to support the notion that "edukation doesn't mean everything" but I'm an ME that was 6 credits short of doubling with a BSEE (but didn't care to spend two more semesters acquiring those credits).

A high resistance short is a real thing. If the insulation becomes exceptionally thin (constant pressure and a little vibration helps) the voltage in the wire can start to overcome the dielectric strength of the remaining insulation and start bleeding to ground. As the insulation gets thinner and thinner, the dielectric strength of the insulation between the conductor and the grounding point continues to get smaller and the ability of the current to flow to ground increases. This type of short can bleed any amount of current. The pinched wire I found had very compressed insulation over a 1/2" section but no wires obviously exposed.

Now that I understand the two circuits, there's just not a common connector that could cause identical problems with both headlights at the same time.

I apologize if I offended anyone - I was looking for some information about how the headlight circuit was configured and ultimately hoped my findings might be useful to someone in the future (especially someone considering the high cost of Recon headlights...the headlights are, otherwise, great but they sure could use some work on their electrical connectors and wire routing).

JakeKohl · December 29, 2014

Thanks for the feedback. I finally found the problem. I found a fitters manual that showed that the left and right headlight assemblies have their own grounds so it was very unlikely to be an issue with the ground. After taking the front end apart (including removing the bumper), I finally found a pinched wire on the hot lead to the driver's side headlight. Apparently it was shorting out enough to drop the voltage coming through the headlight relay (causing both to go dim) but not enough to blow the 20amp fuse for that headlight. The thing that stumped me, was that, apparently, the low voltage operation in that semi-shorted condition was enough to blow both headlight bulbs. I wouldn't have thought that would have happened but it seems to be the case.

I also discovered that the Recon supplied wiring harnesses that plugs into the factory harness is of really poor quality. Where their wires enter the back of the plug it's completely open and not sealed. Added to which, the wires are not captured well in the back of the plug and you can pull on them and disengage the blade inside the plugged connection. I also found that one of these was barely making contact inside the plug and had some corrosion on the connection (I've only had these headlights for 6 mo). I sealed all of that up, put contact grease on the plug terminals, installed two new headlight bulbs, replaced the pinched wire, and it's been working great for a week.

JakeKohl · December 30, 2014

The pinched wire won't be the cause of your issue. Does not matter if less than 1mm of wire is shorted out, it will blow any fuse you have up to the max amp that the wiring can take before melting the wire.

You likely found the issue, and corrected it, without even knowing you did. Really sounds like it was a bad connection somewhere that once you unplugged everything and connected them again the issue was resolved for now. From your description of the connectors, you should expect to have connection issues in the future. You may want to replace all the connectors in that kit with connectors like OEM uses, likely Delphi in this case.

I certainly don't want to start a pissing contest (when I was asking for ideas)...but if the wire is pinched against grounded metal and very light electrical contact is being made through a thin remnant of the insulation, it becomes a high resistance short and may not draw enough current to blow a fuse. No bare conductors were exposed but the wire had been pinched/pressed enough that the insulation was exceptionally thin. Given that both headlights are fused individually in separate circuits, are grounded separately, but experienced simultaneous browning out and subsequent failure of the bulbs while all of the other lighting remained unaffected, this seems like a pretty tidy cause/effect. The relay is the only common point and it was fine. Frankly, I can't imagine what else could have possibly caused the issue. There are no shared connectors.

Doug_Scott · December 30, 2014

Its not a pissing contest,. I really do not care if you want to continue thinking that your logic is correct. What is a "high resistance short"? A short circuit is ALWAYS low resistance. That is what defines it as a short. There has been a saying about this forever, electricity takes the path of least resistance. You also cannot take one of the strands of wire inside the wire and treat it like its own circuit.

If you cannot understand how moving wires, unplugging connectors, checking them to make sure they are tight, could actually correct the issue you had, without you knowing it, then I doubt you really have any idea of how it even works. Good luck to you, but remember, a little bit of knowledge is a dangerous thing,

gmtech4 · December 29, 2014

Thanks for the suggestions. Running a second ground wire is probably my next step when I get the time (which I'm short of at the moment...this will involve removing the front bumper to get the headlights out because the Recon units are slightly larger than the factory units and I can't get them out with the bumper end-cap in the way). I would really like to shoot the voltage steps but since the $18 bulbs burn out in a matter of minutes, this isn't a great option...but that does give me an idea; I suppose I could temporarily connect a cheaper turn signal bulb or something to do the tests with. I have a bunch of those laying around.

I'm hoping someone knows how the grounds are routed from the hi-beam / low-beam circuits and where they terminate so I can check that termination first (assuming they are separate).

Also....will a halogen bulb blow because of a ground problem?

Alldata.com for $27/yr , get that and not rely on anyone , Internet based service manual

Doug_Scott · December 16, 2014

Take a look at battery voltage, both when truck not running, and with truck running as well. Sounds more like overcharging than a ground issue.

JakeKohl · December 16, 2014

Take a look at battery voltage, both when truck not running, and with truck running as well. Sounds more like overcharging than a ground issue.

I wondered about that too so I've been keeping an eye on it. It's scared me before by dropping down somewhere around 11 volts (which I found out was normal as part of the energy/fuel savings system). Today, however, I noticed the voltage guage over 14 volts - and that's the first time I've ever noticed that.

...researching it a bit and that too seems normal.

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