OB99W Posted February 2, 2007 Share Posted February 2, 2007 Is this true? I was looking at wiring diagram few days ago, and seems like there's are relays for power going to left and right headlights, but the ground goes all through the steering wheel switch. I'm thinking about trying upgrading the harness, not before I measure the voltage drop on lights though.I haven't looked at the wiring of more-recent models, but certainly the 90's models have the common hot power switched via relays while the steering-column-mounted switch controls whether the low or high beam connection is grounded; full headlight current does indeed go through that switch and associated wiring. In terms of the contacts, the relays take the brunt of the abuse when switching from parking to headlights (since the lo/hi switch remains stationary then), but the switch contacts take it when you flip to or flash the high beams. If I were trying to determine if voltage drop was a problem, I'd start with the high beams on and check for drop between the positive battery terminal and the headlights' common positive connection. If a significant drop is found, then it needs to be further tracked down; it could be in relay contacts, fuse block, connectors, the ignition switch, etc. If no significant drop is evident on the hot side, I'd next check for one from the negative battery terminal to the ground side of the headlight high beams, and then flip the switch to lows and check from the battery neg to the lows' grounds. A drop in the ground side could be due to contact resistance in the switch, connectors, poor chassis ground, etc. Link to comment Share on other sites More sharing options...
nipper Posted February 2, 2007 Share Posted February 2, 2007 Is this true? I was looking at wiring diagram few days ago, and seems like there's are relays for power going to left and right headlights, but the ground goes all through the steering wheel switch. I'm thinking about trying upgrading the harness, not before I measure the voltage drop on lights though. That has to be the ground of the relays, not the hedlights. The relays are just remote switches (if you will). As long as they operate, the size of the ground doesnt matter. Now it is possible that the contacts are dirty on the load side. Check the voltage drop acroww the load side of the relay. Check your hedlight terminlas and grounds. Also bulbs do get old and loose power. What condition are your lenses in? nipper Link to comment Share on other sites More sharing options...
dmanaenk Posted February 2, 2007 Share Posted February 2, 2007 That has to be the ground of the relays, not the hedlights. nipper Nope, headlights ground literally goes through the switch. I can post a diagram My lenses ar fine, I clean them not so long ago, bulbs are few month old h4 osram +50 I think. Link to comment Share on other sites More sharing options...
OB99W Posted February 2, 2007 Share Posted February 2, 2007 Nope, headlights ground literally goes through the switch.[...] Sorry, Nipper, but this is correct. As I said in post #26 of this thread "full headlight current does indeed go through that switch and associated wiring". Perhaps if you or I were designing the circuit, the switch would just control power to relay coils, but Subaru didn't consult with us (well, certainly not with me). Link to comment Share on other sites More sharing options...
nipper Posted February 2, 2007 Share Posted February 2, 2007 Sorry, Nipper, but this is correct. As I said in post #26 of this thread "full headlight current does indeed go through that switch and associated wiring". Perhaps if you or I were designing the circuit, the switch would just control power to relay coils, but Subaru didn't consult with us (well, certainly not with me). That almost defeats the purpose of having a relay. What did they do, take lessons from fiat or lucas on wiring? nipper Link to comment Share on other sites More sharing options...
OB99W Posted February 2, 2007 Share Posted February 2, 2007 That almost defeats the purpose of having a relay.Certainly to a significant degree. What did they do, take lessons from fiat or lucas on wiring?Possibly; isn't the full title "Lucas - Prince of Darkness"? Link to comment Share on other sites More sharing options...
OswaldtheBold Posted February 3, 2007 Share Posted February 3, 2007 Certainly to a significant degree. Possibly; isn't the full title "Lucas - Prince of Darkness"? Yes, and FIAT is the acronym for "Fix it again Tony". Link to comment Share on other sites More sharing options...
Slegacy96 Posted February 3, 2007 Share Posted February 3, 2007 Really? I love my silverstars. Had em since my '96 LGT (which had awful lights) I must say that they do work better with the reflector lights in my '99. Or these foglights would be a good addition: A time consuming install though. But it was worth it. Link to comment Share on other sites More sharing options...
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