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Guest Message by DevFuse

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glf hatch dash lights issue ;/

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8 replies to this topic

#1 petey


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Posted 03 July 2012 - 11:53 AM

Hi all

Does anyone know why i would have the battery meter,stop lamp and brake fluid lamps illuminated on the dash at all times?

Sometimes very dim,other times quite bright even when driving...tends to vary depending on engine speed,sometimes makes no difference they stay on

Battery is holding charge,have no issues starting even if left for a week or two and meter on dash is stating its charging and rising and falling with revs

Have noticed f i disconnect the block connector from the back of the alternator the lamps all go out....

Help please,its an 84 GLF hatchback,guessing its just a dodgy connector somewhere but just wondered if anyone else has had same issue before i start replacing alternator etc

Thankyou :)

#2 Cougar


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Posted 03 July 2012 - 01:57 PM

To fix the problem you are most likely going to have to replace the alternator even though it appears to be charging the battery ok. Normally the alternator provides a backfeed voltage on the lamp lead when it is working normally and that turns off the warning lights. When you turn on the ignition without starting the engine the lamp lead is near ground potential and that turns the warning lights on using power which comes from the ignition switch.

#3 djellum


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Posted 04 July 2012 - 01:19 AM

the volt meter shouldn't move at all, no matter the revs of the motor. at least it should never drop a significant amount. if it drops below 12 at all something in the charging system isn't right.

might try checking the ground wires. a lot of stuff can go wrong when the ground connections get old and bad. a couple of extra ground connections doesn't hurt and can help a lot with dim and dodgy lights.

also an old school trick is to start the car and then unhook the battery. the alternator is supposed to produce enough to run the car + charge the battery. if you notice a change, for better or worse, then I'd look at the alternator. a parts store can test them but it doesn't always show faulty.

the other part in that system that goes bad is the voltage regulator. Im betting that the one on your car is built into the alt, but they aren't always so you may want to check that.

with engine speed a factor i would first throw a couple of extra grounds in the system, since its free. if that doesn't help, get the alternator tested.

#4 naru


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Posted 04 July 2012 - 08:21 AM

Bad alternator diode.
Confirm by verifying AC voltage is present at alt. output.

#5 TheLoyale


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Posted 25 July 2012 - 12:30 PM

This is interesting, I am having a similar problem. My Brake Fluid, Stop Lamp and Hand brake indicators are all lit up on the dash (Dimly while running) I have no Voltage indicator illuminated, and the volt gauge is reading average voltage, which fluctuates with the turn signals on (Like a typical Subaru)

I am going to check it out, and see what I find. I will post back with any helpful info.

#6 l75eya


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Posted 25 July 2012 - 01:12 PM

Alternator on it's way out.

#7 TheLoyale


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Posted 25 July 2012 - 01:31 PM

So here is what I found. While I had it running, I unhooked the battery, Ran the same. Hooked it back up. I than tested the voltage coming from the output of the alt, 14v+ and increases with RPM goes almost to 15v.

After I unhooked the battery, and hooked it back up, I no longer have any dash lights flickering, they are all off. The red square on the voltage gauge is still lit up, is this normal?

I know with Toyota, when the red square is lit up, that means there is an issue with the charging system, does this hold true to Subaru as well?

Voltage gauge is steady around 13v.

#8 GeneralDisorder


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Posted 25 July 2012 - 04:29 PM

You need to check for AC ripple current, not DC voltage. You should not have more than a few hundred millivolts of AC ripple at the most.

AC current superimposed on the voltage output from the alternator will defeat the diodes in the idiot lamp circuits and cause the "Christmas Tree" to light up in somewhat unpredictable (model to model/brand to brand) fashion.


#9 Cougar


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Posted 26 July 2012 - 09:25 AM

I think GD is correct. Turn on the head lights and blower to high then check for AC voltage across the battery while the engine is running around 1500 RPM. Using a digital meter you should see less than .1 volt of AC. Also recheck the DC voltage since things seemed to have changed after you did the previous testing.

Edited by Cougar, 26 July 2012 - 09:28 AM.

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