Alternator light

[WotEver]

Hi Col. It's a resistor. Probably wired across the alternator light to help excite the alternator. 

We already know something's wrong because the lamp is lit. With the resistor being in parallel with it then yes, it'll get hot. 

[bigcol]

Hi Tony

Oh ok then, when checking the waiting etc, bloody burnt my self, as in wanted the wife to kiss it better lol

knowing it was hot hot, 2 more times it got me, turned the engine, ignition,engine off after that .

amazing something like that generates so much heat amongst that wiring?

 

col

 

[WotEver]

12 minutes ago, bigcol said:

amazing something like that generates so much heat amongst that wiring?

Well it's only supposed to carry current (and hence get hot) for a few seconds until the alternator starts charging at which point it will carry no current (and the charge light will go out). So yes, it's another good reason to get the problem fixed. 

[Tony Brooks]

And the current it normally carries is only the maximum the warning lamp will pass so less than half an amp & more likely less than one quarter. When the fault is cured it won't even get warm.

[Eeyore]

edited as I didn't read the whole thing!

Edited August 26, 2017 by Eeyore

[Sir Nibble]

Let's try again. It's a failure of supply to the lamp, the white wires. That's not a guess, it's experience of over 40 years as an auto electrician. Seen it a thousand times before. It's a fairly common symptom. Get hold of a test lamp or meter and it will take seconds to prove it.

[WotEver]

Yes, you did say the same a fortnight ago

On 13/08/2017 at 12:32, Sir Nibble said:

Not unusual. You have lost the ignition supply to the lamp. When the alternator kicks in it feeds back through the light and finds a negative through other ignition dependant stuff on the same circuit. What else isn't working? Check fuses.

 

[Tony Brooks]

As I did in post 3. This diagnosis has to be addressed. It would not surprise me if it turned out to be a faulty ignition switch.

Take the warning lamp feed wire off the ignition switch and cobble it onto the main feed terminal - a single big wire on probably a 9mm blade, there may be a suitable 6mm blade twined with it. The light should come on. Start & rev the engine and the lamp should go out and stay out as normal. If it does not you have a problem between alternator output terminal and that big wire, more likely between the battery and that wire.

Refit warning lamp wire & report back  the results.

[Sir Nibble]

Looking at the picture, the thing is wired to the old British standard colour code where white is an infused ignition supply, evidently the white to the two lamps are visibly separate so it is likely that the supply to the domestic alternator lamp is relay switched.

[WotEver]

15 minutes ago, Sir Nibble said:

the white to the two lamps are visibly separate

That statement confuses me, Snib. It appears to me from the photo that it's looped from the adjacent lamp which is in turn looped from the one next to it. 

[bigcol]

Hi there folks

 

thanking you for advice.

im now digesting what's been posted, and to rig up a test bulb.

will be working this through this morning

with your help

We fixed the BT together, anything is posible

 

col

[bigcol]

The two alternator lamps are the far 2 on the left

and the engine alternator light which stays on is the 1st on on the left

 

if I have a voltage Mtr cheap one, how would I use the Mtr as apples to a made up bulb tester

 

 

Just to say, the buzzer has never worked, but this was always the case even before this alternator problem

[Sir Nibble]

2 hours ago, WotEver said:

That statement confuses me, Snib. It appears to me from the photo that it's looped from the adjacent lamp which is in turn looped from the one next to it.

You're right, that's my eyes. The lamp in question is fed from the purple.

[bigcol]

So what do I need to do now to test the feed or something, I am thick, and don't know what wire to join,link,and what for??

for the helpers I know it must be frustrating, but I haven't a clue.

Just to say, the buzzer has never worked, but this was always the case even before this alternator problem

 

col

[WotEver]

3 hours ago, Sir Nibble said:

You're right, that's my eyes. The lamp in question is fed from the purple.

Ahh yes, of course it is

I forgot it was the top lamp. 

Although that does raise a side question of why the resistor is getting hot...

[Sir Nibble]

Not having a clue is no crime, not having a clue and still offering advice is. Look for a negative wire on one of the instruments, it should be black. Connect one lead from the meter to that and with ignition on contact the other lead to the purple on the lamp. It should show 12V but it won't because that's the fault. Follow the purple wire testing at every join you find. When you find voltage you have located the fault between the first place you find it and the last place you didn't. Almost certainly at a connection.

set the meter to dc volts which will be marked V with some dashes ---- over a single unbroken line. A bulb with two bits of wire on will work just as well.

[bigcol]

Ok Sir Nibble

 The one not workinwhen I put leads from volt Mtr on the purple terminal to the green terminal shows nothing

 

The one that is working when I put the same on the other alt  light  2 whites  and 2 brown colour wire one of which gos to the buzzer and the other can't see, which is on it shows 11.4 v

the white hot thing both ends connected to this lamp but is linked by the other wires

 

??????? Please what does this tell you

And the white thing is hot hot,when ignition on

[bigcol]

When engine running the light comes on and measures 11.4 volts

with engine running the white thing is cool as a cucumber

and when I put volt Mtr on the terminals with the wires no voltage at all

thats because the light is out of course I imagine?

[WotEver]

20 minutes ago, bigcol said:

Ok Sir Nibble

 The one not workinwhen I put leads from volt Mtr on the purple terminal to the green terminal shows nothing

 

The one that is working when I put the same on the other alt  light  2 whites  and 2 brown colour wire one of which gos to the buzzer and the other can't see, which is on it shows 11.4 v

the white hot thing both ends connected to this lamp but is linked by the other wires

 

??????? Please what does this tell you

And the white thing is hot hot,when ignition on

Yer doing it wrong

Put one meter lead on a good -ve terminal or even a clean bit of hull. Leave it there. 

The other meter lead will read 12V on the white wires but won't on the purple wire. Follow the purple wire back and keep going until it does read 12V. Now you've found the break. 

[WotEver]

Oh, and you do this with ignition on and engine NOT running. 

22 minutes ago, bigcol said:

with engine running the white thing is cool as a cucumber

Good, that's as it should be. 

[bizzard]

2 minutes ago, WotEver said:

Yer doing it wrong

Put one meter lead on a good -ve terminal or even a clean bit of hull. Leave it there. 

The other meter lead will read 12V on the white wires but won't on the purple wire. Follow the purple wire back and keep going until it does read 12V. Now you've found the break. 

Swap the hot white thing for a cucumber Col.    Try what Snib told you to do.  A photo of the wires on the back of your ignition switch would be helpful.  It might be worth removing the hot white resistor for now, you might have to rev the engine a bit more to excite the alternator into charging thats all, you can always put it back.

[bigcol]

Okay the ignition test was ignition on only and it Does not come on! OFF Which is wrong

 

 

i did try the same with engine running and it comes on

[bizzard]

7 minutes ago, bigcol said:

Okay the ignition test was ignition on only and it Does not come on! OFF Which is wrong

 

 

i did try the same with engine running and it comes on

You've already told us that Col.    Do the checks that Snib said in post 41.

[bigcol]

37 minutes ago, WotEver said:

Yer doing it wrong

Put one meter lead on a good -ve terminal or even a clean bit of hull. Leave it there. 

The other meter lead will read 12V on the white wires but won't on the purple wire. Follow the purple wire back and keep going until it does read 12V. Now you've found the break. 

Ok with just ignition on, on the alternight that works okay with white wires

when lead is connected to hull and the other lead connected to white wires it reads 12.6 volt.

but the light with the white wires is the domestics which works at it should.

 

Below is the light on the end that works opposite than it should do

its the end light which is mucking about, which has the purple wires x2 and a green wire 

when I have one lead to hull, and the other lead to the purple or green wire shows nothing

[Sir Nibble]

9 minutes ago, bigcol said:

Okay the ignition test was ignition on only and it Does not come on! OFF Which is wrong

 

 

i did try the same with engine running and it comes on

There is little point in putting a meter across a lit lamp. Re read my instructions and wotever's post 44 and try again. Bizzard makes a good point suggesting temporarily disconnecting the resistor.