Mk1 Warning Lights. Help needed.

[-J-]

When I start the car engine bay cooling fan light and battery discharge light is on. Any ideas?

[LimeyMk1]

From what I recall that's the alternator, 1st check is if the belt's slipping or the pulley is seized up.

[un1eash]

Yup alternator at fault. Belt could be slipping or missing, or it could be the IC regulator has gone on the alternator.

[-J-]

Everything was fine with alternator belt was tight and pulley was not seized.

And those lights are no longer there? What happened?

[-J-]

Warning lights have come back. I was metering the battery voltage and it was 12.1v so maybe the alternator is broken?

[LimeyMk1]

Sounds like it may be on it's way out the voltage at the battery with the engine running should be 13.8 to 14.2 volts (courtesy of Peter @ S-bits).

Next job:

Check all three pins of your alternator plug show around 12v with the ignition on and that the main charging terminal is secure.

[un1eash]

If that's with the engine running then yes I would get the alternator checked, what's the voltage at the alternator?

[-J-]

Yes that was when engine was running. It's hard to check those pins because I don't get my hands over there if they are under the alternator? And the problem is like on/off/on/off now it's charging and after new start it is not charging

[elbon50]

And the problem is like on/off/on/off now it's charging and after new start it is not charging

That suggests brushes worn down beyond min level

[-J-]

But why the engine bay cooling fan light is also there?

[SuperRedMR2]

Water pump pulley runs off of the alternator belt.

[-J-]

So when alternator is not working car thinks that there is no belt to drive water pump?

[PW@Woodsport]

It has absolutely nothing to do with the water pump.

The engine bay cooling fan and the alternator/battery warning light are on the same circuit at the clocks, so if either have a fault both lamps are illuminated.

Check you have around 12v on each terminal of the plug with ignition on, these cars suffer just as many wiring failures as they do alternators, also check the main charging terminal on the alt is secure and tight, they have been known to snap off.

[-J-]

I checked that plug and all three pins showed 11.3-11.7v and same with the second cable top off alternator.