Warning Lights

Got a strange problem.
After driving for 5 or 10 minutes the ABS light and red charging light both come on. After that they'll stay on most of the time but do sometimes go off and then on again. There are no ABS or ECU fault codes and it continues to charge even though the lights on. I've checked connections and earths and can't see a problem.
Looking at the circuit the lights do seem to be connected and linked to a 'sensor resistor'. I think I've found the resistor in the relay box on the drivers side wing - but what does it do?

My guess is an alternator problem when it warms up???

First check your bottom pulley.
The outer ring may have detached from the inner rubber.

Cheers Stu, just took the belt off and had a look at the pulley and think it's OK. Whether the light is on or off it's charging OK so everything must still be going round.

To me sounds like an earth fault or loose connection somewhere. Before I took mine off the road, my abs light would come on when cornering hard so that should be interesting

What voltage is it actually charging at when the light comes on? It might be the resistance of a wire going up when it / the engine heats up causing a voltage drop

Try disconnecting the alternator grey plug see if the lights go off?
Had this issue recently when my alternator gave up.

Only just noticed your thread on much the same fault which confirms what I thought about it being the alternator. I did change the alternator for a spare I had, but that didn't work at all so I put the old one back. (Don't know why I kept a dead alternator as a spare...)
Next time it does it I'll try the plug and see what happens but looks like I'll have to get another alternator and give that a try.
The charging voltage looks OK at about 14 to 14.5 volts and I've never seen it higher than that.