No lowbeams - 2005 tb ext

[VAPOR33]

I have no lowbeams on my 2005 tb all of a sudden....these worked for 6 months since I bought the truck.

I have tried replacing fuses 3 and 6 under the hood, new headlight bulbs, changing relays around with a relay that worked for testing. I have pulled all fuses under the hood and they all look good.

What works:
Parking lights
Hi beams
Turn blinkers (front and back)
Fog Lamps
Brake Lights
Dashboard controls all work for lights including: Fog lamps, the interior master button or whatever that is on left, the rotating interior knob and dash intensity lights and finally turning the top knob from auto to manual.

Anyone have any ideas?

 

[C-ya]

Doubtful that the wires on BOTH sides of the truck failed, unless a common ground was lost. Or the Headlamp Driver Module itself went TU. Haven't heard of that happening, but if the relays (45 & 46) were swapped, there's not much left.

 

[Robbabob]

Both bulbs replaced yet? I know it probably isn't the bulb, but that could be possible.

 

[Wooluf1952]

You said you changed the bulbs. When you put the truck in gear do the DRL's work?

 

[VAPOR33]

You said you changed the bulbs. When you put the truck in gear do the DRL's work?

Nope...

@Robbabob - Yes I changed the bulbs, they are both brand new.
@C-Ya - Where is the headlamp driver module?

 

[Mounce]

It's one of two black (solid state) relays side-by-side in the under-hood fuse box. When standing by the drivers fender, it's the one on the right closest to the windshield. On the fuse box diagram it's labeled "HDM."

You can swap it with the other black relay (which powers the fan clutch) for a quick 'n easy check to see if it has failed or not. If the other relay works, pick up a replacement. They're kinda pricey in stores but you'll want to get the AC Delco brand which is OEM for GM's because lesser replacements have been known to self-destruct and melt. (not too bad on Ebay but I imagine this is a need it now kind of thing and you can't wait for shipping.. http://pages.ebay.com/link/?nav=item.view&id=271283703722&alt=web )

But let me get this straight, when you turn the headlight switch all the way to the right, do they come on?

 

[Wooluf1952]

Is it possible that both relays are bad? (45 is for the fan and 46 is for the headlights)
It's been cool enough that the engine fan hasn't been needed.

 

[VAPOR33]

@Mounce no they dont come on if switched on manually

 

[C-ya]

@C-Ya - Where is the headlamp driver module?

Looking at it closer, they are apparently calling the relay the module. Doesn't make sense to me, but hey...

 

[Mounce]

Yeah, low beam relay = "headlamp driver module." Kind of a common failure part.

Have you tried swapping those relays yet, vapor?

 

[Blckshdw]

First post says that he did.

At this point, I would break out the trusty multimeter, and start testing for power at different points along the circuit (relay sockets, fuses, connectors, bulb sockets, etc). Once you find out where the failure point is, where there's no power, you can target your troubleshooting better.

 

[Bluto4x]

Just to clarify, what relays did you test Vapor.

 

[VAPOR33]

Sorry had a busy weekend....lol

It wound up being the HDM Relay and I got it from a local Autozone for 36.00 bucks. A little pricey but I wanted it that day, suppose I could of got it cheaper online?

For those looking for the part, here ya go - http://www.autozone.com/electrical-and-lighting/relay-headlight/duralast-relay-headlight/206179_0_0/


Thanks for the help everyone !

 

[Mounce]

Glad you got it fixed! But yeah, could've gotten an OEM relay online $9 cheaper but I understand this was a time sensitive issue and you couldn't wait for shipping.

http://pages.ebay.com/link/?nav=item.view&id=271283703722&alt=web

 

[Wooluf1952]

You put in a new relay (#46) and the headlights now work? You should now switch #45 and #46. If the low beams don't work after the switch, you need to get another relay or you may have overheating problems.

 

[VAPOR33]

You put in a new relay (#46) and the headlights now work? You should now switch #45 and #46. If the low beams don't work after the switch, you need to get another relay or you may have overheating problems.

I've already replaced the bad relay, everything works as intended

 

[Blckshdw]

I've already replaced the bad relay, everything works as intended

Right, but initially you said you switched the bad headlight relay, with the fan clutch relay, and that didn't fix the problem. Brand new relay added the mix tells us that your fan clutch relay is also bad...

edit: Rereading the thread, it looks like you didn't get to the HDM until later down the line, so which relays were you swapping out initially?

Side note, you may want to change the engine designation in your signature graphic

 

[Mounce]

When I saw that he didn't know what the HDM was, I knew he hadn't swapped it. Also curious about what relays you were swapping..I'm guessing high beam?

 

[triz]

I got that as well. I think there was confusion as to what relays he might have actually swapped.

 

[VAPOR33]

Yes you are correct, I had no idea what the HDM was....lol
The relays I did swap had no effect because I never touched the HDM....didn't know what it was for.
Upon finding the HDM, I swapped with the Fan relay and it worked. So I went to autozone and bought new relay...and replaced the dead one.

Sorry for not clarifying in my OP...haha