No low beams but high beams work

Steevo

Well-Known Member
#1
Last night, driving in an 05 TB, the low beams go out.
Pulling the turn signal lever turned on high beams which do work, drove home like that.
I noticed pushing the turn signal lever forward turns on low beams, same as pulling would.
The person driving for some reason couldn't do that.
Today I looked at the low beam fuse, no problem found as expected.
I noticed putting the auto lights to on, they do work, but it is daytime.
Clicking the switch to the left has no effect, lights are off. But it is daytime.

The person whose car this is doesn't usually drive at night.
What should I look at?
 
#2
Check the headlight relay by swapping it with the fan relay. IIRC, there may be a recall for these defective relays.
 

vipergg

Well-Known Member
#3
Replace the headlamp drive module which is basically a electronic relay. This is a known problem and certain later years like 2007-9 was recalled for this issue. If you can get it from the dealer, the part was modified to better withstand heat under the hood in the fusebox .
 

Matt

Silver Supporter
#4
If you can get it from the dealer, the part was modified to better withstand heat under the hood in the fusebox .
At a cost of about $130. The recall is for 06+ but the issue isn't confined to those model years as I'm battling the same thing in my 02.
 
#5
Probably could pick one up at a pick-n-pull for cheap (read $0 :biggrin: ). If you get one for the fan clutch, it should be in good shape since it's a much lower amperage draw.

Hey, @Matt, you already have the fan one you could use :biggrin:
 

Matt

Silver Supporter
#6
@Mooseman :crackup: Done that mate. At this stage it's behaving itself, but if it starts flashing again I'll bite the bullet and get the updated version.
 

tcurlee

Active Member
#7
Hey guys ,, having the same issue with the lights. driving to work all the lights went out but I could push the stalk forward for the hi beams and drive with them on ( pissing off everyone around me). Later that night, same day (dark out), same thing happened only this time no lights AND no hi beams unless I kept the stalk manually pulled back in the "flash to pass" mode. Also, no taillights either - is that related to all this as well? I see headlight and fan relay swap mentioned then I see headlamp drive module referred to. Are they the same thing ?? I did the fan-headlight relay swap and drove to work in the dark this AM and had no light issues. I assume that is a temporary fix so what should be my next step as far a parts purchase ?
That fan relay,, is that the clutch fan or the interior blower fan ??
 
#8
Yours sounds like it's having more issues than just the relay/module (it's the same as the cooling clutch fan's). When you say all lights, do you also mean the parking lights?
 
OP
OP
S

Steevo

Well-Known Member
#9
I got a look at that car again. Lights are working.
The part is like this one.
https://www.partsgeek.com/gbproduct...8zR-YgoRBcIFjThbhoCIeIQAvD_BwE&ad=47584901292

There are two like that, fan and HDL
They show no signs of heat damage as some of the pictures people have posted, but these are smaller parts. The one on some threads that look melted, they are bigger. That might be the electronic drive module. This is a relay. Schematic on side.
Different year.
 
Last edited:

xavierny25

Well-Known Member
#10
I got a look at that car again. Lights are working.
The part is like this one.
https://www.partsgeek.com/gbproduct...8zR-YgoRBcIFjThbhoCIeIQAvD_BwE&ad=47584901292

There are two like that, fan and HDL
They show no signs of heat damage as some of the pictures people have posted, but these are smaller parts. The one on some threads that look melted, they are bigger. That might be the electronic drive module. This is a relay. Schematic on side.
Different year.
That is the relay that goes bad when the headlights start going out and acting funky. I have had to replace 3 so far 2 on my brother-in-law's Trailblazer SS and 1 on my Envoy. None of them showed signs of melting or being deformed, no burnt smell either. Heads up you should only purchase the acdelco brand of this relay must other if not all others won't hold up and could start more issues later on.
 

tcurlee

Active Member
#11
Mooseman, yes, the last time it happened ALL the lights were out parking and tail lights and the hi beams would work if I kept the stalk pulled back ( like I said above ). The time before, I could push the stalk forward and the hi beams would stay on. I did that relay swap and took it for a ride and had no issues. since then, I haven't driven it in the dark. So what do you think ??
Yours sounds like it's having more issues than just the relay/module (it's the same as the cooling clutch fan's). When you say all lights, do you also mean the parking lights?
 
#12
Unless that module/relay was shorting out or something, it shouldn't affect the park lights or high beams. I'd be checking the wiring and grounds.
 
#13
Hey Mooseman,, I did that relay swap about 2 months ago and I've had zero issues with lights since then. I'm assuming that was the problem and i'm thinking I should just go ahead and get an ACDelco relay and install it before the same thing happens to this one !?
 

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