Question about GMC Cars & Trucks
All other lights work fine. Checked the fuses, replaced the HDM relay, replaced both the bulbs, Replaced one of the headlight connectors even though neither one showed any signs of wear or damage or melting but they still won't come on.
I'm not sure what else to try. ??????/ Try looking at a wiring diagram an using a DVOM - digital volt ohmmeter an test the electrical circuits , rather then just replacing parts . If you don't know how to test , suggest you take it to a qualified repair shop. Test for B+ - battery positive voltage at the HDM relay an for control from the BCM . Checking for codes in the BCM would also be a good idea.
DTC B2575 Headlamp Control Circuit
When the body control module (BCM) senses a request for headlamp or daytime running lamp (DRL) illumination, the BCM sends a pulse width modulated (PWM) ground signal to the low beam headlamp driver module through the low beam headlamp driver module control circuit. The low beam headlamp driver module will illuminate the headlamps, adjusting the intensity based on the PWM signal received.
Free wiring diagrams here http://www.bbbind.com/free-tsb/ Enter vehicle info. Year , make , model an engine size. Under system click on lighting , then under subsystem click on headlamps . Click the search button then the blue links one at a time . https://www.youtube.com/watch?v=SO-eKuhCOqc&t=125s
Do you know how relays work ? https://www.youtube.com/watch?v=Gg20X-FwGzg&t=183s
Posted on Feb 05, 2019
Cud b flaw in harness wiring from age or vibration. Mite hava module issue. Swingit into a partstore..freehelp
Posted on Feb 05, 2019
Get the help from service and repair manual with diagram to locate and fix the problem on your own and you will get the manual from the given link https://toolsnyou.com/Brands/gmc-vehicle-service-manuals/
Posted on Feb 06, 2019
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Posted on Jan 02, 2017
Check your headlamp relays under the hood, should be located on either the L/H or R/H fender well , could be inside a black plastic box labled fuses and relays... there will be a label on the underside of the lid to this box locate the relays as per lables... please rate my help thanks...
Posted on Aug 06, 2009
SOURCE: 2006 GMC Envoy low beam
Hello, try to start by checking the headlight relay and headlight fuse. You
also may want to check to make sure the bulbs aren't blown out. If those
parts check out to be fine and in working order, you may need to
replace the turn signal assembly in the steering column. This part
controls the hi/low beams. This may sound crazy but, when GM wired
their older trucks, they wired the headlights to go from the battery,
to the hi/low beam switch, then to the headlight switch (to the left of
the steering wheel) then out to the light bulbs. You can kind of test
to see if this part is good by making a fist and (with your headlights
on) gently hitting the plastic cover for your steering column that is
right behind your actual steering wheel. This could cause your
headlights to flicker on and off.
Posted on Aug 09, 2010
Relay in fuse box under hood on driver side wheel well labeled HDM, #46 on 2004 Envoy XUV. Swap with relay #45 labeled "Fan" to test. That was my problem.
Posted on Sep 13, 2010
SOURCE: 2002 Acura TL low beam headlight
How to Shift my headlight beam from position.
from I replace my headlight it's spatting directly on the ground..What can i do to change it from position
Posted on Feb 15, 2011
The problem is likely your multi purpose signal light switch. If you take the lever and move it from hi to low beam will the low beams come on? It is common for this multi purpose (real expensive ) switch to fail after a period of time! The steering wheel may have to be removed, to change it. The air bags will also need to be disabled so as not to active them while removing the switch.
Posted on Mar 19, 2011
Tips for a great answer:
Oct 16, 2016 | 2004 GMC Envoy
Full Intensity Mode: This mode is used by features that require full low beam headlamp intensity such as low beam headlamp operation in manual or auto modes (nominal: 100% duty cycle).
Off Mode: This is the default mode of the system that will occur when none of the features described above are active. The BCM will deactivate its PWM output (0% duty cycle) during this mode.
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