And Swartlkk was right that our Blazer/S10 headlight schematics are the same as the Bravada for future reference and all of our vehicles have only two low beams, two high beams, and possibly two fog lamps. The DRL function uses those lamps.

Thanks Kyle.

George

 

And now that we know that we all have the same headlight schematics, you might find this thread interesting:

https://blazerforum.com/forum/2nd-ge...-lights-43157/


George

 

I'll dig into what I can with this new info and get back to you guys. THanks for all the help.

 

Ok I believe I've traced this thing down to the body control module. Can the BCM be traded out part no. for part no. or is there more to it? There's a bunch on Ebay.

 

Unless you have the existing BCM cloned to the new one you will have passlock security issues and you will have to perform a relearn (unless you are lucky enough to have the same passlock resistor value). As far as general programming goes I believe that a BCM from an identical configuration will work besides the passlock issues but I am not 100% on this, never had to deal with a BCM issue so I don’t know for sure if they are all unique to the VIN.


George

 

Passlock? What the heck is that? I guess I'll have to do a little research. All I have is a normal key to start. There is no FOB or security activation I have access to.

 

Your vehicle has two security features, unauthorized vehicle entry (door locks) and unauthorized vehicle start/run. The latter is managed by the passlock system, a dedicated module behind the ignition switch module which contains a hall effect sensor and unique (one of ten) resistor value. When you turn the ignition key cylinder a hall effect sensor in the passlock module allows the BCM to read the dedicated resistor value to decide if the fuel system should stay enabled to allow the vehicle to run properly. A new BCM would need to go through the programming process to recognize your existing passlock resistor value. If either the passlock module and/or the BCM is replaced then you must go through this programming process.


George

 

Ok update. I got a replacement BCM off Ebay. That was not the issue. And it also is part of the passlock system as @GeorgeLG stated.
Here's the info I have now. If I ground the Grn/Blk (A11-C1) wire that is part of the brown BCM wires, the lights work. From here, I need help as to just how things are actuated. I'm using the wire diagram posted above. I'm having a real tough time figuring out the flow after the lights switch from DRL to low beam night lights.
According to the diagram, the other wires shown hooked into the BCM are for foglamps. There is one white wire (A11-C2) which does what? Is that the wire needed to signal the BCM to ground the Grn/BLk wire? Or is that how it works at all?

 

Lets start with just the low beams.

1. If you put the headlamp switch in the manual on position you get no low beams, correct?
2. But if you ground grn/blk/C1/A11 with the headlamp switch in the manual on position, you get low beams?
3. What do you mean by "part of the brown BCM wires?
4. Does any of this matter as to whether its light or dark outside?

If you really can only get low beams by grounding C1/A11 then you may have the wrong kind of relay in the "headlamp relay-ground position". There is a type A and type B version where pins 30 and 86 are reversed.


George

 

1. Correct. All the other lights come on, no headlights
2. Yes the headlights do come on
3. The BCM has 3 colored connectors feeding into it. The Brown or "C" connector has the headlight wires.
4. When it's light outside my DRL's work fine. When low light conditions it switches over automatically but no headlights.
The "headlamp relay ground" has 5 pins and a part no on the relay itself. It only goes in one way and didn't get mixed up as far as I know. Here's an Ebay picture