anyone figure out how to make the "off" position work yet on the 2003+ canadian gm trucks? I'm told it may be as simple as a programming change on the ecm. The way they work right now is the headlights are on if it's running and its dark out, period. I've been thinking of doing a mod with a separate switch but would rather find the right way if it's possible.http://www.dieselplace.com/forum/smileys/Confused.gif

On my 2004 if you hold the switch to off and push the button underneath they go off untill you shut it off and start it again.

Here's the way I understand it, based on reading Helms 2002. I do not have a Canadian Truck, so my lightswitch may be different.


I don't think it's programming in the ECM, but programming in the Body Control Module, (BCM). This is programmed based on Regular Production Options, (RPO).


Per Helms, "The Automatic Lamp Control (ALC) and the Daytime Running Lamp (DRL) cannot be turned off on the Canadian Vehicles".


Some possible RPO's controlling this might be listed below:


Z49 Export Canadian Modification Manditory Base Equipment


T78 Headlamps Control - Delete


T62 Lamp System Daytime Running - Delete


Helms 2002 references :


Circuit description - page 8-479


Lighting schematics - page 8-330


The Headlamp Relay & Daytime Running Lamp Relays are both controlled by the BCM, schematic pages 8-299 & 8-300.


BCM reprogram - page 8-641





Can anyone else help with this? That's about all I know. Hope this helps.

thanks guys for your replies. Sweibel- turning my switch and pushing the button doesn't work on mine. Good thought though! Thanks modified for the info!