20 replies to this topic

[tiger99]

You don't need much charge in the battery to do the test, as you are not applying a heavy load. If there is enough for sidelights to work, you have plenty.

Edited by tiger99, 30 January 2016 - 12:23 AM.

[my_first_mini]

Ok, so I tested the small cable to the alternator, live when car is running and not when the ignition is on.

So the alternator is fine?

Before you pull the dash out, remove the alternator plug and the small wire is the warning light wire to the red ignition light, switch the ignition on and place a jump wire into the small wire on the plug and earth it out to the engine block

If the light comes on the diode pack in the alternator has blown
If the light does not come on the bulb is blown or there is no 12v ignition feed to the bulb, or there is a break in the wiring

DON'T TOUCH THE LARGE BROWNS AS THAT WOULD BE A DEAD SHORT

Depending on the type of alternator you may not have 2 large browns and the warning light wire in a plug, they may be on separate terminals

[my_first_mini]

So tested the wire, doesn't light with ignition switches but look lights when engine is running.

Still no warning light, have switched the bulbs to check if it was the bulb, still doesn't light

Don't know where it will be on your alternator, as they vary, but there is always one thin wire and one or two much thicker brown wires, It is the thin one that you need to jumper to earth to check that the warning light works.
 
On the classic Lucas alternator, there is a 3 pin plug, with springy wire locking clip, on the "back" of the alternator ("front" is pulley end). The thin wire in that plug is the one. So it is indeed on the left as you look at it.

[David128]

Hi You now need a decent multimeter to trace that small wire from alternator up to the ign warning lamp in dash it goes through a multiplug  connector at the rear of the clocks which could be a dirty or bent connector. if it gets through the connector it maybe that the circuit track has cracked easily repaired with a soldering iron and wire.

Most important be methodical and certain that the wire has good continuity from alternator to ign lamp.

Edited by David128, 01 February 2016 - 03:54 PM.

[my_first_mini]

When you say decent...
Will this do? http://www.halfords....3&storeId=10001

Hi You now need a decent multimeter to trace that small wire from alternator up to the ign warning lamp in dash it goes through a multiplug  connector at the rear of the clocks which could be a dirty or bent connector. if it gets through the connector it maybe that the circuit track has cracked easily repaired with a soldering iron and wire.
Most important be methodical and certain that the wire has good continuity from alternator to ign lamp.

[dklawson]

From your previous posts I am not sure how you have tested this.  Before you spend any money please try the following.

• Remove the plug from the alternator.  
• Locate the small wire in the alternator plug.
• Make a short jumper a foot or more long and stripped on both ends.
• Stuff one stripped end of the jumper wire into the alternator plug where the small wire is.  Make sure the stripped jumper wire is making good contact with the brass terminal in the plug.
• Switch the ignition on and hold the other end of the jumper wire to a bare metal spot on the engine (cylinder head bolt, water pump, etc).

The red charge warning light should come on.  If it does not, then try replacing the bulb first.  If that does not fix the problem, invest in a multimeter as suggested above.