Brake/Battery Light... Alternator? - Subaru Enthusiasts Car Club of the Sierras

WRCsubeRS · 2009-02-28, 09:25 PM

Hey all,

So my car is all back together, never did figure out why my engine spit the spark plug out, but never the less, its all running good. Well lately I've been noticing that when at higher RPMs my battery AND e-brake light come on/off/flicker/fade in perfect harmony with one another. I would assume that this is an alternator issue and its about to die. Can anyone confirm or deny this? Thanks All!

Dean · 2009-02-28, 11:16 PM

Check the belt. and all connections, especially the positive lead on the alternator.

What does a volt meter say?

WRCsubeRS · 2009-03-02, 10:46 PM

well i checked all the connections and all seems solid and well, belt is still on and tensioned properly. but regardless, while picking my sister up this evening, my power inverter started beeping at me, and from there it was all down hill.... Tach/Speedo dropped to 0, interior lights faded to nothing, windshield wipers were stalling, started losing engine power. I must say its quite remarkable watching your car die from lack of electricity. So thats it, obviously the alternator is dead, but I was still curious as to find the reasoning behind the brake light AND battery light, so I browsed through my wiring diagrams to find this:

interesting design i must say...

sperry · 2009-03-03, 01:48 AM

Subaru circuits are reduced by a computer so they function as designed with the fewest/cheapest number of parts possible. It's surprising sometimes what the computer comes up with. For example, when I wired my projectors so my low beams would stay on with my highs, there was a latching effect on the hi beam relay any time my fogs were on. So if I flashed my highs with the fogs one, I couldn't turn them off w/o turning off the fogs!

Dean · 2009-03-03, 08:02 AM

Scott is right, they try and minimize costs as much as they can.

Stuff like this was true long before computer optimized circuits. Heck, the only ground wire in cars used to be 6 inches long from the battery to the chassis! Talk about optimization.

There were probably only 2 fuses at one point. Ignition/engine and "accessories"

2009-02-28, 09:25 PM	#1
WRCsubeRS EJ18 Real Name: Cameron Join Date: Aug 2006 Location: Gardnerville, NV Posts: 47 Car: 2002 WRX	Brake/Battery Light... Alternator? Hey all, So my car is all back together, never did figure out why my engine spit the spark plug out, but never the less, its all running good. Well lately I've been noticing that when at higher RPMs my battery AND e-brake light come on/off/flicker/fade in perfect harmony with one another. I would assume that this is an alternator issue and its about to die. Can anyone confirm or deny this? Thanks All! __________________ Everyone knows women are made from sand...

2009-02-28, 11:16 PM	#2
Dean Señor Cheap Bastarde Real Name: Dean Join Date: May 2003 Location: $99 Tire Store Posts: 9,294 Car: $.04 STI Class: Fast,Cheap & Reliable=STI Deal, did somebody say Deal? Oh, Dean, yeah that's me.	Check the belt. and all connections, especially the positive lead on the alternator. What does a volt meter say? __________________ I am a Commodore PET --- Now get off my lawn you kids...

2009-03-02, 10:46 PM	#3
WRCsubeRS EJ18 Real Name: Cameron Join Date: Aug 2006 Location: Gardnerville, NV Posts: 47 Car: 2002 WRX	well i checked all the connections and all seems solid and well, belt is still on and tensioned properly. but regardless, while picking my sister up this evening, my power inverter started beeping at me, and from there it was all down hill.... Tach/Speedo dropped to 0, interior lights faded to nothing, windshield wipers were stalling, started losing engine power. I must say its quite remarkable watching your car die from lack of electricity. So thats it, obviously the alternator is dead, but I was still curious as to find the reasoning behind the brake light AND battery light, so I browsed through my wiring diagrams to find this: interesting design i must say... __________________ Everyone knows women are made from sand... Last edited by WRCsubeRS; 2009-03-02 at 10:48 PM.

2009-03-03, 01:48 AM	#4
sperry The Doink Real Name: Scott Join Date: Nov 2002 Location: Portland, OR Posts: 20,335 Car: '09 OBXT, '02 WRX, '96 Miata Class: PDX/TT-6 The way out is through	Subaru circuits are reduced by a computer so they function as designed with the fewest/cheapest number of parts possible. It's surprising sometimes what the computer comes up with. For example, when I wired my projectors so my low beams would stay on with my highs, there was a latching effect on the hi beam relay any time my fogs were on. So if I flashed my highs with the fogs one, I couldn't turn them off w/o turning off the fogs! __________________ Is you is, or is you ain't, my con-stit-u-ints?

2009-03-03, 08:02 AM	#5
Dean Señor Cheap Bastarde Real Name: Dean Join Date: May 2003 Location: $99 Tire Store Posts: 9,294 Car: $.04 STI Class: Fast,Cheap & Reliable=STI Deal, did somebody say Deal? Oh, Dean, yeah that's me.	Scott is right, they try and minimize costs as much as they can. Stuff like this was true long before computer optimized circuits. Heck, the only ground wire in cars used to be 6 inches long from the battery to the chassis! Talk about optimization. There were probably only 2 fuses at one point. Ignition/engine and "accessories" __________________ I am a Commodore PET --- Now get off my lawn you kids...

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