head/dash lights randomly dim

[dubbedup]

hey guys,

I have a wee prob, when im driving along at night if im accelerating my lights will brighten up but when im deacellerating/coasting my lights go quite dim - sometime the stero cuts out. I was thinking alternator on the way out, but it still starts and drives fine, I have a link so checklights not really an option, i also have a GFB pulley kit that might have something to do with it. Car is a 93 GC8.

Any ideas?

[Guest]

sounds like alternator possibly, as it slows its not maken the juice, but is enought to keep the battery chaged to start it . . . possibly

do they dim at idle? if so, get teh old voltage tester out and see what the voltage is across the battery

-smurff

[dubbedup]

hahaha, didnt even think of getting the multimeter out....DUH!!!

Have only driven it once outside of the city (last weekend) and you dont notice it around town cos of the st lights. so it could have been happening for a while, i just have never noticed til now.

[Guest]

ahhh, well you may as well try it, if its dimming at idle, and ur voltage is like 12V, but then when u giving it some revs it gose up to the 14v mark, its ur alternator doing it to you. wouldnt replace the alternator till it dies though

-smurff

[dubbedup]

Yeah i wanna polish up my alt housing anyways so mite just get my spare one rebuilt...mmm shiney

[Guest]

oohhh they look so nice polished!, ive not been albe to get the pully off mine, so i stopped wanting to do that, but hopefully the desial alternator i get for the subby will come apart easy

-smurff

[dubbedup]

yeah it was bit of a mish when i put the pulleys on....had to borrow a pulley puller( or whatever they are called) and it poped right off.

[Guest]

ive got a pully puller. . . i just couldnt get the nut off hahaha

-smurff

[Koom]

Try it with an alternator thats got a normal pulley on it. Are the GFB pulley's underdrive ones?

[dubbedup]

Yep they are the lightwieght underdriven ones, They are designed to work in harmony so not really too keen to put a regualr alternator on...but if i cant fix this problem it cant hurt to give it a shot.

[Guest]

 Koom said:

Try it with an alternator thats got a normal pulley on it. Are the GFB pulley's underdrive ones?

ahh yes i think they are, so at low revs that could cause the drop

-smurff

[dubbedup]

Enough to turn my cd player off(no amps or subs) randomly....

[Koom]

I would've thought that the battery would keep it on but if its loaded at the time i.e. trying to keep the engine running, the voltage could be dropping enough that the headunit's logic tells it that it is being turned off. (Purely a speculative guess )

[dubbedup]

yeah its very random....its what highlighted the fact, then i asked the wife and she said she noticed when i was braking that my lights were getting dim,

[Guest]

did there sterio go off when you had ur lights on and breaking? the low voltage due to alternator, and then voltage drop causeed by all the lights could have then influenced what koom has said in regaurds to the head deck

-smurff

[Koom]

Only time I've had a similar issue was when the alternator had died and I was running purely on battery power. My headunit was one of the last things to turn off, although it couldn't keep the iPod on ;D and once that died there was no way that the engine was ever going to be close to starting again. So obviously your's is still charging at some point but just dropping voltage significantly in some situations.

I'd still guess its the underdrive pulley or second guess is voltage regulator has died/dying?

[dubbedup]

 smurff']

did there sterio go off when you had ur lights on and breaking? the low voltage due to alternator, and then voltage drop causeed by all the lights could have then influenced what koom has said in regaurds to the head deck

-smurff

yeah it was at nighttime (lights on) and i was out in the wops having a wee spirited drive (down 3mile hill for the locals to meet b42000 for fireworks) had stereo cranking lights on and i started to brake coming up to a tight corner and the stereo died, it was a 55k corner or similar with the big yellow diagonal signs, i thought the stero mussed have skipped, but it started back on track one instead of midway thru a track...thought odd, anyways it wasnt till i was coming back up the hill pushing it thru the corners and noticing the reflection on the signs and my lights being bright then dim.

[quote name='Koom said:

Only time I've had a similar issue was when the alternator had died and I was running purely on battery power. My headunit was one of the last things to turn off, although it couldn't keep the iPod on ;D and once that died there was no way that the engine was ever going to be close to starting again. So obviously your's is still charging at some point but just dropping voltage significantly in some situations.

I'd still guess its the underdrive pulley or second guess is voltage regulator has died/dying?

where is this regualtor and how can i check it?

[Guest]

i remember my civic, alternator dies, drove all the way to strongs from botany and back for a new alternator,

just down the road from home, speedo stoped working, read deak started turning on and off. tuned off everything

and coz it was a quite day, did very little breaking, car died just at the bottom of my drive on the foot path

changed the alternator were it died hahaa

-smurff

[Guest]

 dubbedup']

did there sterio go off when you had ur lights on and breaking? the low voltage due to alternator, and then voltage drop causeed by all the lights could have then influenced what koom has said in regaurds to the head deck

-smurff

yeah it was at nighttime (lights on) and i was out in the wops having a wee spirited drive (down 3mile hill for the locals to meet b42000 for fireworks) had stereo cranking lights on and i started to brake coming up to a tight corner and the stereo died, it was a 55k corner or similar with the big yellow diagonal signs, i thought the stero mussed have skipped, but it started back on track one instead of midway thru a track...thought odd, anyways it wasnt till i was coming back up the hill pushing it thru the corners and noticing the reflection on the signs and my lights being bright then dim.

[quote name='Koom said:

Only time I've had a similar issue was when the alternator had died and I was running purely on battery power. My headunit was one of the last things to turn off, although it couldn't keep the iPod on ;D and once that died there was no way that the engine was ever going to be close to starting again. So obviously your's is still charging at some point but just dropping voltage significantly in some situations.

I'd still guess its the underdrive pulley or second guess is voltage regulator has died/dying?

/quote]

where is this regualtor and how can i check it?

most regulators are in the alternator these days arnt they?

-smurff

[dubbedup]

Sweet at least and alternator is an easy fix, and prolly have one in the shed.

[Koom]

Think the regulator is part of the workings of the alternator itself. Not sure of test methods for that. Guess just put a multimeter across it with various load on the electrical system.

[dubbedup]

Sweet im going out for lunch day so i will update after then. (will check things with a multimeter)

[Guest]

if u strip ur alternator, look into the rear section and theres a load of blak plastice and stuff. . . that load of stuff if ur regulator

-smurff

[dubbedup]

Cheers Smuff,

Mite pull a spare noe apart just to be nosey....

The last volage regulator i had issues with were a 1970s corrola so a bit different to a 93 wrx :-)

[Guest]

yea, the corrola whould have had an external one? with cooling fins on it?

the reg is easy to replace in the alternator. . . just need a very good soldering iron.

-smurff