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2006 WRX
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Discussion Starter · #1 ·
A friend was driving my car home from the dealership (with me following him in another) when I get a call saying the tach and speedo stopped working. We tried to make it home, but I could see his lights dimming as time passed. About 8 blocks from home, the car died.

The battery light was on at the dealership, and I'm not sure if it was on before. I just got my key programmed with my new engine/ECU/immobilizer so the car had not been running on that setup before.

We tried to boost it and it started. After we took off the booster cables, the car just died. The battery would not charge.

I replaced the alternator today and the battery light was still on. I also replaced the battery with another I had laying around the shop. This battery was known to be a working battery and was just pulled off the charger. The same thing happened, battery light stayed on.

Other lights on in the car are:
ABS light - Rear ABS sensors aren't connected, new connectors are to be soldered in tomorrow.
Brake light - ??? Related to not having rear ABS plugged in?
Battery light - Charging issue.
CEL - 4 codes pulled, all to do with the secondary air injection system which was removed. These codes have not yet been flashed out.

I just went over everything with a multimeter and I have no voltage for the B/W wire when I turn the ignition on. We tried jumping that wire to the 12V on the battery to see if we could get the light to shut off (getting the system to start charging) but that didn't work. This is the wire that goes to "ALT" which connects to my DRL and cluster. Everything else is working is as it should (expected voltages, etc.) and I have replaced the ALT fuse with a brand new one.

I am using the RS wiring and the STI alternator.

Any ideas?
 

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James incognito
Black 06 STi & 07 Wagon
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324 Posts
Did you test the alternator?
 

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2006 WRX
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611 Posts
Discussion Starter · #6 ·
Damn, I really though it was going to be the alternator.

One other thing that can turn on the parking brake light is having low brake fluid. Check that out.
Checked it. It might be the rear ABS sensors that I have yet to solder in OR one of the common wires in that circuit is grounding. I have a feeling that the B/W wire is grounding out somewhere in the bulkhead harness, I'll be hitting the multimeter with Sean today.
 

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2006 WRX
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Discussion Starter · #7 ·
Y wire gets 12V, white gets 12v, B/W gets 0V but has continuity all the way to the cluster and shows continuity (with a bit of resistance) with the negative terminal on the battery.

I pulled out the multimeter, and here are the results:

The Pink circle also shows low resistance when I test resistance with the chassis.

Looks like I have a ground (although I shouldn't) somewhere in the B/W path.
 

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ok terrific.
'95 STi RA rep, rhd yo!
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5,223 Posts
Do you have the wiring diagram to the alternator?
 

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2006 WRX
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611 Posts
Discussion Starter · #9 ·
That's the one in the factory manual. The only other place the alternator is present is in the Power Supply system and the wire in question just goes from the alternator to the ALT fuse. The ALT fuse has been replaced with a new one and still no luck.
 

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Doesn't the field wire from the alternator need to be connected to the idiot light/gauge cluster in order to charge?
I know that's the way it is on an old school "g".
 

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2006 WRX
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Discussion Starter · #12 ·
did ya think about having the battery tested???
Brought the battery home, threw it on the charger, brought it back to the car a couple hours later, started the car and drove home.

We have replaced the battery with one from a working car and there is still a problem. I have worked with a fellow on the other site and traced it down to an inappropriate ground that I most likely hooked up when I did my swap.

Now the car won't start, it was running and driving before :bonk:

Doesn't the field wire from the alternator need to be connected to the idiot light/gauge cluster in order to charge?
I know that's the way it is on an old school "g".
It is.
 

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92 Crown Vic
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629 Posts
do you have a draw (once you get it running). but what about the voltage regulator on the alternator? but i would try new battery (not out of a car) and a new voltage regulator. did you happen to check fuses? and relays?

james
 

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Moderator
06 Wrangler Unlimited
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4,613 Posts
Brake light + battery light generally means a bad alternator.

And like someone else said, it's possible that the "new" alternator you installed is bad. It happened to me one time..
 

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2006 WRX
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Discussion Starter · #15 ·
The B/W wire isn't showing any signal when the car is turned on, therefore there's a ground somewhere on that wire. I'm planning to ditch my DRL (for now), and directly wire the sections from B36 and B62 together and ground the rest of the circuit to the body. If that fixes the charging issue, I'll have to simply use the DRL wire and tap it into a 12V switched power source and leave the rest of that B/W circuit grounded to the body. I have a feeling I connected B137-2 from the STI ECU to that circuit, thinking it was a common ground circuit. I know, I know; 1 single wire that wasn't traced back and 1 issue arises from it.

Question for you wiring gurus:
Does a ground on the ECU act as a ground or does it expect to see a ground? When I cut that wire and just connect the B36-B62 sections of that wire and leave the rest of it unplugged (which should only contain a wire going to the DRL), the car doesn't start. That to me seems as if the ECU isn't grounding properly and would explain the ground in the charging system.
 

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2006 WRX
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Discussion Starter · #16 · (Edited)
Sorry, I should have made myself clear. It is *NOT* a bad alternator. There is no voltage going through the B/W wire when the key is *ON* so there is no current to stimulate the alternator's function.

Edit:
Here are some tests I have done earlier:

I pulled out the multimeter, and here are the results:


Edit#2: When I cut the B/W wires and directly connected them (instead of going to the passenger side of the car behind the HVAC to join up with the DRL), neither light (brake or battery) would turn on at all.
 

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needs more cowbell
95L, 07 2.5i, R6
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Have you tried disconnecting the "wake up" wire at the alternator from the car's harness and manually connecting it, to see if it would charge and keep the car running? At least to have it work until you figure out your wiring issue? You could use a relay to only turn the alternator on when the key is in the ignition position.
 

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2006 WRX
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Discussion Starter · #18 ·
Update! I was able to get the lights to go off! ...but I have another problem now.

When the green plug on the alternator is unplugged, the lights are off. When I plug it back in, the brake light and battery light go on again. Does that point to bad alternator? All I did for the wiring was cut out the DRL portion and I got rid of the constant ground. It's wired exactly how it looks to be wired in the wiring diagram. With the alternator plug unplugged, the B/W wire gets 12.45V or so. With the green plug plugged in to the alternator, I get something like 0.79V. Any idea what the issue could be? I'm thinking dead alternator.
 

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92 Crown Vic
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when you talk about amount of volts. you need to remember that you need power ground and a unit using up that voltage. if you undo the ground anywhere you get voltage all the way thru the wire till the brake in the wire, now if cut power obivous no power thru the wire. so unplugging the wire and not unplugging wire might be normal readings.
oh and i think the starter and alternator are grounded thru the case to the engine.

James
 
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