DRL issues

[Salvaing]

Hi

I live in France (no GM dealer) and own a 40K mile '03 RendezVous.

The problem :
DRL does'nt work and headlight + Inst Clst + rearlight are always ON.
I change ambiant light sensor, relay, fuse. No change.

---

I own the GM Tech 2 scanner and I got the DTC B3857.
DTC B3857 Circuit Description
The body control module (BCM) monitors the high beam headlamp signal circuit by verifying the high beam input.
DTC Descriptor
This diagnostic procedure supports the following DTC:
DTC B3857 Headlamp High Beam Signal Circuit

There is no short or something wrong with high beam, works fine.
I think the BCM is toasted.

My question :

Before change and reprograming the BCM do you think there a procedure to diseable DRL ?
I try this one .. but Mexico is not a listed option.
http://blog.obd365.com/2014/12/24/how-to-disable-drls-with-gm-tech2-scanner/

Best Regards.

 

[AFS585]

I disabled my DRL's by replacing the halogen bulbs with LED bulbs (direct plug in, no driver) and NOT using any resistors or relays to overcome the low voltage going to the LED bulbs. By doing that I still have highbeams but do not have the factory DRLs. My DRLs are now switchback LEDs in the front turn signals (white with parking lights, amber turn signals). i manually switch them on for now but my next modification will use a relay to turn them on automatically just like the factory DRLs.

 

[Salvaing]

Ok thank you for your answer.
BTW I think the best solution is diseable DRL.

But I did not exactly understand what bulbs you had changed to LED ?
9005 high beam bulb ? 9006 low beam bulb ? Fog ?

Can you be more specific or make a diagram ?

Bst Rgds

 

[ryenie]

The code you gave points to a short\open in the highbeam circuit. Removing fuse #14 (DRL) in the underhood fuse box should disable the drl, without having to do anything other than removing it. Also the drl uses the highbeam bulb, just at half power.

 

[AFS585]

Ok thank you for your answer.
BTW I think the best solution is diseable DRL.

But I did not exactly understand what bulbs you had changed to LED ?
9005 high beam bulb ? 9006 low beam bulb ? Fog ?

Can you be more specific or make a diagram ?

Bst Rgds

i changed the 9005 high beam bulbs to direct plug in 9005 LED bulbs.

 

[Salvaing]

The code you gave points to a short\open in the highbeam circuit. Removing fuse #14 (DRL) in the underhood fuse box should disable the drl, without having to do anything other than removing it. Also the drl uses the highbeam bulb, just at half power.

Unfortunately this is not so simple. DRL management is provided by the BCM . If one of the elements that prevents it from working properly (light sensor , full active headlamp, fuse, relay , and others), BCM generates an error, shuts off DRL and lights on headlights , dashboard , rear lights etc. ...

 

[ryenie]

Unfortunately this is not so simple. DRL management is provided by the BCM . If one of the elements that prevents it from working properly (light sensor , full active headlamp, fuse, relay , and others), BCM generates an error, shuts off DRL and lights on headlights , dashboard , rear lights etc. ...

I'm not quite following your logic. Removing the drl fuse should do nothing but prevent the drls from coming on during daylight operation. It may cause a code to show up but shouldn't keep anything else from working. If that were the case a burnt out headlamp or turn signal bulb would also cause all of the lights to quit working as they are all controlled by the bcm. The bcm grounds the drl relay when the headlights aren't on and the light sensor detects it's day time. When the relay is grounded, (via the bcm) it supplies power to the drl fuse, the fuse powers the highbeams in series (this is how it illuminates at half power with no additional resistors or modules). If other lights are being affected i would think you have a different issue. Where you able to erase the code and check to see if it came back. It can take 100 ignition on\off cycles to clear the code on its own once the issue causing the code is resolved.

 

[Salvaing]

A simple ODB reader does'nt recover this code.
I own the GM Tech 2 Scanner, got the B3857 code, erased it but unfortunately it returned...
I do not know what is the correct procedure to test the high beam headlamp signal circuit.

 

[ryenie]

Since you have a tech II you should be able to communicate with all of the modules in the car. Different codes are stored in different modules, have you checked all of the modules for codes? Also, in the wiring diagram for your vehicle, which can't be found online, (found one at the library though), the ground for the right high beam is fed through the drl fuse so i apologize but it does look like removing the drl fuse might keep the high beams from working, but just the high beams, no other lights should be affected. It also may only effect the right high beam if you remove the fuse.

 

[Salvaing]

Check with Tech II : no other codes stored except B3857
Remove DRL fuse : both L&R lowbeam + inst clst + rear light on all time.


There is a lot of tips & tricks to diseable DRL within this site : http://www.lightsout.org/disable.html
But nothing for the RDV ... 🙁

 

[ryenie]

Am working on making some wiring diagrams for the effected lights. But something to check, the drl relay should have 5 prongs on it, the high beam relay should only have 4, if they're swapped, might cause issues.

 

[Salvaing]

Okay.
I'm very interrested in this diagrams.
My RDV drl relay have 5 prongs and high beam relay have 4.

 

[ryenie]

 

[Salvaing]

I already this wiring. I thought you meant a modified wiring to fix this DRL problem. Thx.

 

[ryenie]

From what i can tell, if you remove the relay and jump M5-N6 it will eliminate the drls while still allowing the high beams to function. Cutting the darkblue wire from the right high beam and grounding it should also have the same effect. If you cut and ground the wire you need to remove the drl relay.

 

[Salvaing]

Jump M5-N6 eliminates the DRL ... but light up low beam / inst clst / rearlight. 🙁
I think this is a security system that detects a problem with the DRL and automatically turns on the low beam / inst clst / rearlight.

Should disable automatic low beam / inst clst / rearlight activation and make it manual from the left side dashboard knob.

 

[ryenie]

I really think the other lights coming on is a byproduct of a short somewhere, not some sort of safety feature. Could be on the underside of the fuse box, or maybe a loose connection at the bcm, but i think if you resolve the issue and get the code to clear it will solve the issue of the other lights.

 

[texan01]

I've tried a few tricks to turn off the DRLs on my 04, and it always triggers the light and triggers the normal headlights/parklights to come on. With just pulling the relay or fuse, it triggers the 'fail-safe' mode, so no shorts in the harness or anything else.