Headlights not working.. believe it is grounding issue

Hello,

I am new to Subaru. I have a 2000 outback and I do not have any headlights. I have checked fuses in engine compartment and tested relays. Looking at the wiring diagram I am wondering if my daytime running light relay is keeping me from having a path to ground. I don't know where to find said relay.

Be aware that the headlight wiring is "backwards" on these cars, at least on some model years (including your model) so the power goes from bus bar, via relay and fuse (one for each side), over to the headlights, then back in high and low beam wires to the high/low beam switch and then to ground. When looking at the wiring diagram it looks like the wiring goes through the Daytime running light control module before going to the high/low beam switch.

So now it's time to start tracing which voltage you have in different locations.

Also look in this thread, you might find some interesting things there: https://legacygt.com/forums/showthread.php/wants-see-my-vacation-pixi-6216.html

The DRL relay is just an add-on, that isn't necessary for the normal operation of the headlights, but the DRL control module seems to be the essential part in the wiring part. I'd start with checking the headlight relays in the main fuse box to see if they are actually actuated when expected (ignition on, lights on). That should give a voltage on the fuses 8 and 9 in the fuse box. If the relays aren't activated by the DRL control module it's possible that it's a wiring issue or that the DRL control module has died, but you need to trace that further.

Personally I always leave the headlight switch in the "On" position since the headlights are turned off when the ignition is turned off anyway, no need for DRL. And using the main beams as DRL is actually burning out the main beams so they may not work when you want them.

Some extracts from wiring diagrams, these seems to be the relevant parts:

I have studied that diagram and from what I can tell I have jumped the ground (black) with either the red or the yellow/blue and I get the desired headlight to turn on. If I unplug the DRL module I still don't get lights. I am missing where the Hi/lo beams are getting their ground connection. The DRL has two sets of connectors one white and one black. I disconnected the white thinking that this would bypass the DRL but no luck.... The diagram shows that there is a NC relay that is the link for the ground for lighting. I really appreciate you sharing your wealth of knowledge. My son is 15 and this is his first car. I am looking forward to the learning experience he is in for..

Thanks

Phil

On my 95 hi and lo get their ground through the stalk switch so the actual connection to chassis is probably in the cabin. I don't have an FSM for your year so I can't be sure, but I expect it is the same.

Lots of stuff is switched ground these days because it is easier for the ECU or some other module to use a big FET to switch on the low side than on the high side.

I have studied that diagram and from what I can tell I have jumped the ground (black) with either the red or the yellow/blue and I get the desired headlight to turn on. If I unplug the DRL module I still don't get lights. I am missing where the Hi/lo beams are getting their ground connection. The DRL has two sets of connectors one white and one black. I disconnected the white thinking that this would bypass the DRL but no luck.... The diagram shows that there is a NC relay that is the link for the ground for lighting. I really appreciate you sharing your wealth of knowledge. My son is 15 and this is his first car. I am looking forward to the learning experience he is in for..

 

Thanks

 

Phil

B102 is the relay that I am referring to..

You can forget the B102 relay, but the wiring goes through the DRL module between the headlights and the stalk, so if you unplug it you won't get any lights.

But I would start to locate the B71 connector and check what voltages you have there and that the ground pin actually is grounded by measuring the resistance or use a test bulb between battery and that pin.

Do the position lights and the instrument come on when you turn on the lights? That can also be a good clue.