electric nightmares

[s3freddy]

Help! I'm now the very proud owner of a beautiful S3. It runs like a dream and is more fun than I ever thought it could be. That is, until I drive at night. With the lights on for a period of time the car has developed a nasty habit of cutting out. The volt meter on the dash gradually falls into the red, and then it cuts out. This has happened both when the car is moving (70+ on the M27 @ 3500rpm), and also when the car is stationary. The charging light then comes on and everything is fine with the lights coming back on etc, and the car will nearly always start up again immediately... Until I get 100yds down the road, and it does it again... I've checked the battery which reads fine, and the alternator, which gives the same reading when the electrics are off as when they are on... Thought it might be the fan belt, but I've had no overheating problems...

I love the car, so would love to actually be able to drive it all the time...
I don't know if this is a common problem, but the garages I've spoken to are clueless. Any suggestions would be greatfully received

[Colin Blues2]

Could be the fan belt - as the car has an electric fan it won't show up as overheating. They do need to be pretty tight.

Also worth checking the earth points these are notorious for throwing all sorts of odd intermittent problems. It could be that you have a poor connection somewhere that is causing the joint to heat up which increases the resistance until it gives up.

When the volt meter is going down is your charging light on or off?

Have you tried measuring across the battery whilst the volt meter is dropping off? Does the voltage stay constant?

Colin

[GreenV8S]

There's a 4-way connector between the ignition switch and the main loom which is notorious for causing bad connections. You will need to take the lower cover off the steering column to see it. If in doubt, remove the connector completely and solder the corresponding wires directly to each other (bearing in mind that some of them are permanently live; you'll definitely want to disconnect the battery while you do this).

[numbnuts]

I would also check all the connections to the fusebox.

[s3freddy]

thanks very much for the advice, will check them all out this week and let you know.