Low beam Headlights seem to

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Car54
Posts: 87
Joined: Sun Nov 14, 2021 10:08 pm
Location: Allentown, PA

Low beam Headlights seem to

Post by Car54 »

All,

Forgive me if this has been already discussed.

I just got my ‘14 yesterday. Drove to work this morning and now home both in the dark.

Low beam looks like its under 1/2 power IE daytime running lights.

Switch to Hi beam and its nice and bright.


Ive fiddled with the headlight dial, nothing changes.

Suggestions please, and yeah the passenger headlight is all fogged over after the car wash today. Had to ahe was a dirty dirty dirty girl.
HoldOn SV

Re: Low beam Headlights seem to

Post by HoldOn SV »

If they are actually not switching intensity disregard the following, and consider correcting that 1st:
Sounds like you have some lens seal issues (inherently common and compounded by up-fitted strobes). Factory replacements are around $750 each, but less expensive aftermarkets are available from Australia (if you're willing to gamble on getting them here atm).
I couldn't afford either option this year, and very fortunately the upfitter didn't ruin my lenses installing the strobes. So, I spent half a Saturday restoring mine, which included the following:
Removed the lenses (bumper cover has to come off). Then I removed all the bulbs and projectors, and washed the lenses inside and out. Next, I wet-sanded and polished the lenses. Finally I resealed any suspect areas for moisture intrusion (at the very least the strobes).
Be sure to orient the projectors correctly. See link: https://commons.m.wikimedia.org/wiki/Fi ... ematic.svg
https://drive.google.com/file/d/1NYpC-E ... p=drivesdk
Car54
Posts: 87
Joined: Sun Nov 14, 2021 10:08 pm
Location: Allentown, PA

Re: Low beam Headlights seem to

Post by Car54 »

I saw your post on what you did. That will be step 2.

My lights DO NOT change in intensity from DRL to Low Beam.

Hi beams work great, just not going to be that moron out there running around with hi beams on all the time.

Any suggestions???
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elc32955
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Re: Low beam Headlights seem to

Post by elc32955 »

Once in a great while you have agencies that monkey with the car's wiring to put their own wigwag or flashing setup in independent of the established police wiring upfit points, check for any suspicious splicing or extra wiring in circuit. You can download the Caprice technical manual for your year car in the files section that will give you a breakdown of all the normal police upfit wiring so you can check those circuits as well. From what I read of your symptoms, (Customer states that) the headlights just go into DRL mode from the key on time and do not switch to low beam intensity from either command of the car (photocell at whatever light level it automatically triggers) or manually through the headlight switch. This brings to mind maybe a BCM problem since that's where the actual commands come from to light the lights.

One other suggestion, if you know the agency the car came from go pull the maintenance records on the car to see if this problem existed before the car went onto the sale lot. You can also try talking to the fleet maintenance folks there (if they were self-maintained) to see if maybe there WAS something in the upfitting they can tell you about that might cause this, might be worth the phone call if you luck out & get a decent person on the other end. Don't be surprised if they play dumb or are bad with returning calls though.

This smells like possibly BCM to me however...

Good luck!
Eric
System Manager and your tour guide for the day. 2015 Caprice w/LFX, former NC DPS staff car. Partial hybrid G8/SS/Camaro SS interior mods, SS MyLink radio upgrade, 2016 Camaro V6 rims, GMPP Malibu chrome exhaust tips, otherwise bone stock for now.
Car54
Posts: 87
Joined: Sun Nov 14, 2021 10:08 pm
Location: Allentown, PA

Re: Low beam Headlights seem to

Post by Car54 »

Bcm not what i was hoping for. Assume its got to go to the dealer. I have no experience with playing with these computers.


I do need to get it in for the seat belt recall and to have 2 keys and fobs programmed
HoldOn SV

Re: Low beam Headlights seem to

Post by HoldOn SV »

Car54 wrote: Tue Nov 23, 2021 6:17 pm Bcm not what i was hoping for. Assume its got to go to the dealer. I have no experience with playing with these computers.


I do need to get it in for the seat belt recall and to have 2 keys and fobs programmed
I'd also consider replacing one of the low beam bulbs for comparison before taking it in.
https://www.autozone.com/collision-body ... 526312_0_0
Car54
Posts: 87
Joined: Sun Nov 14, 2021 10:08 pm
Location: Allentown, PA

Re: Low beam Headlights seem to

Post by Car54 »

A few days later… more like weeks…

I changed out the bulbs as suggested, 3M’d the poop out of the lenses and got “better” light output from them. Butttttt

They still don’t seem to be bright enough.

FINALLY today I got a few minutes to poke around.

I opened up the fuse panel under hood. Looking over all the relays and fuses. Hmmm the relay for the low beam headlight is missing.

So, can anyone of you gurus here tell me if

1. What the relay #/part # it is. Can’t find it on Napa, advanced, auto zone etc, web sites.

A. Is the relay moved elsewhere for the addition of the wig wags/stobes etc??

B. This could be the reason the lights seem to be in DRL mode.

Appreciate the help.
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rcg530
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Re: Low beam Headlights seem to

Post by rcg530 »

I just checked my 2014 Caprice engine fuse box and relay slot "55 LO BEAM RLY" is also empty and my low beam headlamps work correctly.

The BCM is in charge of providing reduced power (DRL mode) or full power to the low beam headlamp bulbs based on my searching of the service manual.

It looks like power for the low beam headlamp bulbs goes out BCM connector X4 (pin 1 = right / pin 18 = left) and then it runs through connector X126 (pin 32 = right, pin 16 = left). Then the power goes to connector X120 (right headlamp / pin 7) and X110 (left headlamp / pin 7).

Here's the low beam headlamp control logic:

Low Beam Headlamps

The headlamps may be turned ON in 3 different ways:
• When the headlamp switch is placed in the ON position, for normal operation
• When the headlamp switch is placed in the AUTO position, for automatic lamp control
• When the headlamp switch is placed in the AUTO position, with the windshield wipers ON in daylight conditions, after a 6 second delay

The BCM will also command the low beam headlamps ON during daylight conditions when the following conditions are met:
• Headlamp switch in the AUTO position
• Windshield wipers ON
• Vehicle in any gear but PARK

When the BCM commands the low beam headlamps ON, the operator will notice the interior backlighting for the instrument cluster and the various other switches dim to the level of brightness selected by the instrument panel dimmer switch.

For headlamp operation, the body control module (BCM) monitors three signal circuits from the headlamp switch. When the headlamp switch is in the AUTO position, the three signal circuits are unaffected and the BCM relies on the ambient light sensor input to turn the headlamps and daytime running lamps ON and OFF. When the headlamp switch is placed in the OFF position, the headlamp switch headlamps OFF signal circuit is grounded, indicating to the BCM that the exterior lamps should be turned OFF. With the headlamp switch in the PARK LAMPS position, the headlamp switch park lamps ON signal circuit is grounded, indicating that the park lamps have been requested. When the headlamp switch is in the HEADLAMP position, both the headlamp switch park lamps ON signal circuit and the headlamp switch headlamps ON signal circuit are grounded. The BCM responds by commanding the park lamps and low beam headlamps ON. With the headlamp switch in the HEADLAMP or AUTO position, the BCM responds by applying battery positive voltage to the left and right low beam headlamp control circuits illuminating the low beam headlamps.
2014 Chevy Caprice PPV | RetroCarGuy530 YouTube Channel
HoldOn SV

Re: Low beam Headlights seem to

Post by HoldOn SV »

Seems like a BCM issue, but you'd need to confirm it's receiving the command too. Consider checking the connector pins and harness.
I haven't tested my H11 Sylvania LEDs for variable intensity compatibility, (which if incompatible with this feature might be a suitable resolution to your issue), but I know they work well in my projectors, with no noticeable BCM driver overload (flicker/cut out). In this case, I'm only vouching for a product I've used. In other words, you might have different results with other part numbers/brands (for better or worse). I hope this helps. Cheers! 8-) https://shop.advanceautoparts.com/p/syl ... 12068853-P
Car54
Posts: 87
Joined: Sun Nov 14, 2021 10:08 pm
Location: Allentown, PA

Re: Low beam Headlights seem to

Post by Car54 »

I have to educated myself on all the info you guys have been awesome in posting here.

Few things mentioned in the post. My interior dash lights do change in intensity, day to night or driving thru a tunnel. I don’t think it’s the switch then???

The sentinel on the dash isn’t locked in place, it’s sitting kinda crooked, will look at that.

Switching the headlight knob thru the various setting does absolutely nothing in headlight output.

However, the consensus here is that it had to do with the BCM.

There’s a bunch of connectors that look to have been cut etc primarily on the passenger side in front of the fuse panel. I’ll see what there and take a few pics of it all there. Perhaps there is the problem.

Will remove the passenger kick panel and see what up in there as well. I did find the green white wire not connected there, connected with like colored wire under the heater box and now have a fully functioning horn!

Just do not understand why the PD would even mess with the BCM to get their equipment installed in the car.

I found wires cut and tucked into the headlight housing when I changed out the bulbs, they seem to be for the strobes that are in there.

Trying to resolve this as much as I can before taking it to the dealer to figure it out.
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