Battery Warning Light

[Bob Tucker]

My brain is now black & blue.......never did get elecktrickery

[Guest Jonnyround2003]

I have no earth for the alternator just two cables from it ! If I change the cable from the alternator to the neutral on the battery it lights up but that won't tell me if I have a problem with the battery really confused now

[Guest Jonnyround2003]

I have no earth for the alternator just two cables from it ! If I change the cable from the alternator to the neutral on the battery it lights up but that won't tell me if I have a problem with the battery really confused now

[Guest Jonnyround2003]

It's like I'm missing a neutral have power from ignition have cable from alternator that's it ?

[Longboarder]

It is quite possible that someone has used a different loom and even random different coloured wires. Alternators have at least two terminals on them often three or four. There is no neutral terminal on an alternator. Its case is the neutral which is bolted to the engine which is earthed to the negative terminal of the battery.

 

What alternator do you have and what are its terminals labelled?

 

Have you checked that the ignition live wire is delivering 12 volts to the ignition bulb? Have you checked the continuity of the wire from the ignition bulb to the alternator? A simple way to check the circuit is to pull the small wire off the back of the alternator and rig a temporary contact to earth on the engine block. With the ignition on the bulb should now be lit. If it is then you have an internal alternator fault.

 

Nigel

 

Sounds like a vicky green loom. It had a fat brown a thin brown and a brown/yellow. The brown/yellow is the ign lamp to alternator one.

Edited September 29, 2014 by Longboarder

[Guest Jonnyround2003]

Hi Nigel, Thanks for your help it must be a faulty alternator the light worked before it a sierra dohc 1997 one has three connections one to battery one to bulb the only one not connected is marked B TO BATTERY D TO BULB W ? do I need to run a neutral from the bulb with the cable from the alternator together ? as I have no neutral at the moment

[Longboarder]

So can I check this is what you have?

Alternator with a plug that has two big spade connectors and a smaller spade connector.

A big fat brown cable to one of the big spade connectors. B

A thin brown/yellow to the small spade connector. D

(Is there not a thin brown to the second big spade connector? B There may have been originally if this is a VG loom.)

A unused connector on the alternator marked W. (This terminal is used on diesels for rev counter output)

 

What make of alternator do you have?

 

Nigel

 

Plug below like yours? OK all the wrong colours but are the connectors like this?

[Longboarder]

do I need to run a neutral from the bulb with the cable from the alternator together ? as I have no neutral at the moment

There is no neutral wire. The ignition lamp has two terminals. One is for the ignition live wire. The other is for the brown/yellow that goes to D on the alternator.

 

Nigel

 

The brown/yellow performs as a neutral when the alternator is not turning.

Are you wiring up a separate ignition lamp or are you wiring up an ignition lamp in a sierra instrument pod?

Edited September 30, 2014 by Longboarder

[Guest Jonnyround2003]

Hi Nigel , The bulb is just small circular one with two spade connections I have switched live one side and the other side goes to d on the battery if I change that side to a neutral the bulb works. I have screwed bolt connections on the alternator not sure of make . I have checked continuity from the bulb to the alternator and its fine.Will double check it tonight ! Thanks for your help !

[Longboarder]

the other side goes to d on the battery if I change that side to a neutral the bulb works.

What about if you take the wire off the D on the alternator and earth it. This would confirm its continuity and that it is the wire you think it is if the bulb lights.

 

Nigel

Edited September 30, 2014 by Longboarder

[Guest Jonnyround2003]

Hi Nigel , I did what you said an ran a cable from

the alternator d to an earth leaving the bown and yellow to the bulb and it lights up ! Can't tell if power goes thought the yellow and bown but had no sparks but the car won't run at the moment. What do you think I should do ?

[Guest Jonnyround2003]

The alternator was new and bulb worked before it must have gone faulty !

[Longboarder]

I didn't understand your answer clearly. I see my advice could be ambiguous. I meant disconnect the brown/yellow from the D post on the alternator. Short the end of the brown/yellow wire that you have just disconnected from the alternator to earth with a length of wire. I'm not clear this is what you did. If it is what you did and the ignition lamp lit up then that proves the continuity of the circuit as far as the alternator. Don't short the D post to earth as that adds no information. Sounds like a Bosch alternator, type 6 on the Brise chart below.

I saw your other thread. That's a bit worrying as a group of faults, all appearing at the same time should be carefully thought about as probably related. Have you checked all fuses, earths and the work you did before the fault appeared? Is the battery fully charged?

 

Nigel

[Guest Jonnyround2003]

Hi Nigel , yes it type 6 sorry hope this makes sense I took the brown yellow cable from the alternator and grounded it then the bulb works so the fault must be at the alternator as for the other problems I think its coincidence no fuses have blown just ran low on fuel and picked some crap up

[Longboarder]

Check the engine earth path back to the battery anyway. No earth could produce both problems.

 

Nigel

Edited October 1, 2014 by Longboarder