No Battery Light, Alternator should be good

[Croley]

Here is what is happening.

On my '83 320is for the longest time my battery light was dim while running and some times off. My battery never died but some times when i turned off my car i could hear the relief relay licking back and forth. I wasn't an electrician and still am not. A week ago I went to change my oil and when taking off the oil filter i heard the relief relay clickin and saw some black smoke rising i figured i was touching something that made that happen. Low and behold all of the wires were bare in one place or another. I figured id fix that.

Well Now my battery light doesnt turn before or after i start the car and the battery definately is powering the car. I read many posts and had the alternator looked at and got new brushes and bearings and it is still draining. As far as i know there isnt something giving the car a slow drain while car is on or off.

I feel like in my readings i saw somewhere that if the bulb (in the dash?) is a gonner from touching wires together or something, the alternator wont power the engine or charge the batt.

I'm confused and dont feel like taking the dash apart, I haven't before and I'm just not sure...

[tomscat1]

I am a little confused by your post.

Your battery is only used in starting your car. Once the car is started, your alternator 'powers' the car, and replenishes the battery for the juice used to get the car started.

If your battery is ' definitely powering the car", that means that your alternator is not functioning, and you will shortly end up with a dead battery. (Battery drains while starting and driving, nothing replenishes lost battery juice = dead battery.) I am not sure that this is what you mean.

Does your battery go dead? If so, then either your alternator is not functioning properly, or you have a drain on your electrical system somewhere.

The dash light issue that you have read about refers, I believe, to a "battery light on, ignition off" scenario... this happened to my car.... and the problem in my case was a bad diode in the alternator/voltage regulator, I forget which. I believe the voltage regulator is in the back of the alternator on my car, btw. Did they check both on yours?

If you found bare wires around there, there is a good chance that something has shorted out.

And are you saying that no matter what you do, that battery light on the dash NEVER comes on? When you turn the key 'on', that battery light should light up. If it does not, the bulb may have burnt out.... I don't know if the failure to light is a symptom of another problem or not. I would defer to the more experienced electrical guys in here.

Good luck, let us know what you find.

[Tom D]

the way robert bosch designed my old boxer motorcycle, was to use the alternator lamp to excite the field. that in turn gets everything going. i believe the E21 is wired the same.

so, if the bulb is burnt out or the blue wire from the run/start bus bar, to the lamp, to the D+ (terminal 61) is bad or un-plugged, then the alt. will not work.

[tomscat1]

the way robert bosch designed my old boxer motorcycle, was to use the alternator lamp to excite the field. that in turn gets everything going. i believe the E21 is wired the same.

so, if the bulb is burnt out or the blue wire from the run/start bus bar, to the lamp, to the D+ (terminal 61) is bad or un-plugged, then the alt. will not work.

"I don't know if the failure to light is a symptom of another problem or not. I would defer to the more experienced electrical guys in here."

And there he is now! Thank you, Tom D.

[epmedia]

Croley - that little blue excite wire that connects to the alt is prone to breaking at the spade connector if the alternator vibrates alot. If it is broken, it may not look broken, you have to tug on it to verify.

If you end up pulling the gage cluster, it's quite simple, let us know if you need help with that.

[Croley]

Thanks guys,

The battery light never turns on... any more, it did before i re-wired the shorted wires and it no longer does.

By battery does die yes, especially one night when i was driving home i would use the hand brake instead of the breaks while sitting at a traffic light and dim to parking lights when not moving and when i got home you could barely even hear the engine turning.

I also just switched 2 relays to see if the relay was bad but the light still would not turn on before ignition. There is battery power (with the car off) going to the bottom red wire, im not sure if that is supposed to happen or not, but when i turn the key neither of the blue wires have power going thru them.

The blue excite wire is clipped into the spade, ive taken it off and put it on several times, so it should be attached.

So I'm guessing the next step would be to replace the batt bulb in the dash?

Thanks again!

[epmedia]

The blue excite wire is clipped into the spade, ive taken it off and put it on several times, so it should be attached.

So I'm guessing the next step would be to replace the batt bulb in the dash?

If the spade stays attached to the blue wire while tugging on them, it should be fine.

I believe you won't get voltage to the blue wire if the bulb is burned out (key on, I forget if it's "+", or "-"), so yes, I suppose it's time to pull the gage cluster:

Disconnect speedo cable about 6 inches from the cluster.
Remove round knurled nut under cluster, on the steel part of the dash.
Place towel between cluster and steering wheel.
Get both hands up in there.
Pull the cluster toward you and wiggle, from the TOP of the cluster.
It will POP out as soon as the sticky tape releases, be carefull.
You will see the 2 wire harnesses, disconnect those.
Some folks claim having to remove the steering wheel, but I think you won't have to, to change the bulb.

That's about it, piece of cake.

[Croley]

If the spade stays attached to the blue wire while tugging on them, it should be fine.

I believe you won't get voltage to the blue wire if the bulb is burned out (key on), so yes, I suppose it's time to pull the gage cluster:

Disconnect speedo cable about 6 inches from the cluster.
Remove round knurled nut under cluster, on the steel part of the dash.
Place towel between cluster and steering wheel.
Get both hands up in there.
Pull the cluster toward you and wiggle, from the TOP of the cluster.
It will POP out as soon as the sticky tape releases, be carefull.
You will see the 2 wire harnesses, disconnect those.
Some folks claim having to remove the steering wheel, but I think you won't have to, to change the bulb.

That's about it, piece of cake.

Thanks man, ill get on it and see what i can do

[epmedia]

I edited my post, was not Ninja fast enough for you...

I believe you won't get voltage to the blue wire if the bulb is burned out (key on, I forget if it's "+", or "-"), so yes, I suppose it's time to pull the gage cluster:

[Croley]

Welp... the bulb is still good I guess I'll re-wire the blue excites

[epmedia]

Welp... the bulb is still good I guess I'll re-wire the blue excites

Just out of curisity, before you dig in too fast:
See if the blue excite wire has "+" or "-" voltage to it with the key on.

I'm not certain of the full behavior of the light when the voltage regulator on the alt goes completely bad.

[Tom D]

as i stated above: the excite wire comes off the run/start bus bar in the fuse box, that means there is only power to the bulb with the key ON. the ground is the brown wire at the back of the alternator.

1) pull the bulb and check it (which you did and you said it was good) if good then;
2) with the key on, check the bulb socket for 12v. if good then;
3) put the bulb back in, pull the excite wire off the back of the alt and with the key still on check for 12 volts at the wire. if good then;
4) pull all the wires off the back of the alternator. using a continuity tester, check between the excite post and the ground post on the back of the alt. you should have a completed circuit.

[Croley]

Thanks for the help, I'm callin it a night for now, but ill see what i can do in the morning

Thanks
-Croley

[Croley]

Well, I checked out the wires and they should be good, I didnt get a circuit from the ground and excite with the key turned and the wires plugged in, I didnt check the bulb socket yet, mainly because its all back together. With the key on i checked the excite wire and no juice coming thru. I thought, what the heck, the excite wire had definitely touched the red wire before so i revered it and turns out the excite is grounded (my checker lit up when going from +battery to the excite) So i'm guessing that my excite wires are being grounded somewhere, dang... What do yall think?

[Croley]

WOW... Some ishmo ... aka yours truely... used cheap easy little wire clip things and didnt check to see if the little metal connector cut through the old thick plastic wire sheath, so therefore there was no wire to wire connection i would have had if i felt like spending a little more time on stripping the wire and then putting a wire nut on the excite wires... long story short, Lights On! Thanks everyone!

[epmedia]

Well, that's a relief!
Make sure the alt pumps out juice too

That excite wire should be soldiered and shrink tubed when you get a chance.

[Tom D]

another 'atda boy' for robert.

[epmedia]

another 'atda boy' for robert.

Thanks Tom, but OP seems to have figured it out with all input, and that darned quick connect (I despise those things).
The only fair input I had was forgetting if the excite wire was "+" or "-" with the key on

[Tom D]

corley, with older cars it's not uncommon for the lamp to glow. usually it because of corroded connections.

as you go through the car, pull a connector or two apart, hit it with some electrical contact cleaner and use a little dielectric grease when you put it back together.

i started doing this with my motorcycles, now with my cars and hardly ever have electrical problems.

[epmedia]

^ thanks Tom, that reminds me of all the wire maintenance I've been putting off. My light has been glowing for a couple years. Layne mentioned awhile back about a wire underside the fuse box that should be cleaned to rid that glowing charge light. Soon as my boy gets that e30 back together, that '78 will be mine for awhile, once again (if approved by my wife, of course)

[Croley]

Ahh, Good idea, yeah, now the batt light is brighter while running than it was before i "fixed" it, haha, ill have to check it out, im almost positive the alt is doin its job... i hope so!

Thanks again for everything!

[Croley]

Well... now the battery light comes on... and then is dim... then gets brighter through out usage, and then the battery begins to get weaker. So I am feeling like either the battery has seen better days, or the alternator is not really charging the battery or powering the engine.

[Tom D]

*put a multi meter on the battery with the car not running. it should read around 12.8 volts.
*start the car, the meter should now read 13.8 - 14.8 volts
*turn on the headlights, the meter should drop and then return to 13.8 - 14.8 volts

[epmedia]

Croley - after you installed the alt, did you make sure that the big ground wire between the engine(block) and the alt housing got hooked back up? Our alts (stock) are not grounded, thus rely on that big ground wire to function properly.

If so, may just need a new regulator at this point, but first do the voltage test, as Tom described.

[Croley]

Alright, I'll see what I can do, I'm workn at a camp for the next few weeks, so down time doesnt happen too much, and driving doesnt really happen either, but I'm gonna check it out some time soon... Thanks