Charging problem. Help please.

blue beasty said:

light should come on with ignition as said but even if it does and goes out with engine running it doesn't always mean the alts ok. If it has an internal short the light can go out without charging the battery......just to confuse matters

Click to expand...

that's why an ammeter is always a good idea!

philvy said:

that's why an ammeter is always a good idea!

Click to expand...

seconded ^
was gonna go down this route when the op gets back and if theres still problems.
also depends on the tinkering ability of the op too!

Ok. The bulb for the red warning light seems ok but it does not work. why I am not sure??? Was wondering if I may have dislodged a wire when re connecting the air hose behind the dash and on looking sure enough there is a loose wire which is purple with white. Can't see a purple with white on the wiring diagram, any ideas? No obvious place for it to go.

where the bulb wire attaches to the alternator (white wire, i think) earth it and see if light comes on. if it does its an alternator fault.
if it doesnt come on, check power and the bulb. Your Alternator will not work without there being power on that wire. that wire is the field/exciter wire.


1. The stator windings, this is a 3 phase machine, it has 3 sets of coils.
2. Main rectification diodes, sometimes referred to as the rectifier stack or pack.
3. Field diodes.
4. Field coil, the winding on the rotating shaft in the alternator, connected via the slip rings and carbon brushes to the regulator circuit.
5. Surge protection diode stops the output voltage rising above a predetermined safe level.
6. Dashboard warning lamp.
7. Ignition switch.
8. Battery, stores the charge provided by the alternator. It should be noted that the battery is always connected to the alternator though the main lead
9. To vehicle systems, usually distributed to the circuits via the vehicle's fuse box(es).

Thanks. Will check now

Earthed the bulb wire and sure enough the warning light came on. I will now go down the faulty alternator route. Thanks every one.
Don't suppose anyone know of a company that does an exchange service, don't fancy pulling it apart myself.

Most motor factors will exchange, but a guy that repairs is Burghfield Starter & alternator Centre - 0118 983 2284. Did a good job on mine

mite be worth checking the engine to battery earths - just in case.....

The charge light has a white wire on one side and a brown/white wire on the other. The colours can change with time so your purple/white wire might have started off brown!

Not hot on electrics. But, i had trouble staring my 88 a while ago and the alternator wasn't feeding the battery on start up, because a wire had come loose from the charge light bulb housing. Once this was re-attached securely no more problems. I assumed the circuit is dependent on this connection, to 'tell' the alternator to charge the battery.

A new alternator has solved the problem. Lucas unit was only £38 + vat from mm 4x4.com.

androver said:

A new alternator has solved the problem. Lucas unit was only £38 + vat from mm 4x4.com.

Click to expand...

do you have the old one? if you do maybe put it in the for sales, someone might find it useful (not me obviously because of shipping costs)

Thought about that but as you very kindly gave me a link to repairing it I thought I may hang onto it as a spare.

androver said:

Thought about that but as you very kindly gave me a link to repairing it I thought I may hang onto it as a spare.

Click to expand...

I'd try to repair it now. You never know when the new one will pack up, and it's nice to have a working spare!

True. Will look at the manual and give it ago. Nothing ventured and all that.