I have A 2000 blazer having trouble with headlights. I found they work if i run a jumper wire from HDLP PWR relay negative side of trigger to ground. Was wandering if anybody knows where that ground leads to? I was thinking about running a new ground to the fuse box. but if i can fix whats there i would rather do that. I found headlamp ground relay under dash bench tested relay was good. Haven't tested socket not sure what i should have there. I also have A 98 blazer (planing to use as parts truck) the headlights work with that entire relay block removed.

 

The ' cold' use of the coil is usually the side thats switched by the switch or computer. That isolates the switch circuit from the charging system. Grounding it probably overrides the switch. May be a bad switch.

 

the hot side of the relay coil is getting + switched power. when i was testing it i warped A ground around the negative or cold side prong of the coil and plugged relay in all lights and switches worked. also swapped out headlight switch with A known good one same thing. just looking for a better solution than the way i had it rigged up.

 

So a while a go in an attempt to understand the headlight circuit in preparation for making a DRL and Auto Headlamp override circuit I made a schematic of how the lights work. This does not include the interconnects and is only for understanding how it all works. But you might find it useful.

And yes, I am a bit of a nerd to even have attempted this. LOL

 

Were you able to make an on/off circuit?

Most folks just bend the tab on the relay and install a resistor in the sensor

 

I have been able to make the circuit but I have not tested it yet. My circuit makes it so that I can temporarily disable it. I can't seem to find my thread on it but you might find it. But I'll be posting on it sometime in the future. To make it I had to create a new box with relays that I could remotely control to "blind" the BCM that the truck was in driving mode and what the outside light conditions are.

Apparently some Blazers came with a way to disable the DRL and perhaps the Auto Headlight feature by pressing the Dome Override button 5 times fast. But that did not work for me. I suspect it might have been because my Blazer was first sold in Canada where DRL was mandatory. (DRLs are still not mandatory in the US.)

If you are interested, DM me for more details now or later.

 

It was just more out of curiosity since I’ve already done the resistor/bent tab trick years ago and was happy with it.

I always read your posts and can see you’ve got a pretty good handle on electronics; I especially liked what you did with the additional led for the dimmer switch. I would have done that to my own ride but settled on red led’s for all dash/interior lights since at that point of my restoration, I still had some pretty big things to figure out like my HP Tuners and Tuning School course.

Ive been driving S-10’s for the past twenty years and they’ve definitely found a place in my heart. Lol, at some times I’ve thought it was a love/hate relationship! 😂

 

I ended up just adding a ground to the fuse box that that had continuity to the relay. All lights seem to work normally. Thanks to everyone that commented. And thanks for wiring diagram christine_208

 

I have a few questions, so my headlights aren’t working at all, not even the drl’s and I’ve replaced all the switches, fuses, and relays are all working and have power coming to them, my tail lights work as well, just my headlights don’t work, unless I jump them as you said, could it be caused by that ground relay under the dash? And is there an easier way of checking those or pulling the brb without ripping out the whole dash?

 

I have a few questions, so my headlights aren’t working at all, not even the drl’s and I’ve replaced all the switches, fuses, and relays are all working and have power coming to them, my tail lights work as well, just my headlights don’t work, unless I jump them as you said, could it be caused by that ground relay under the dash? And is there an easier way of checking those or pulling the brb without ripping out the whole dash?