S3 Electrical Problem

[Neil Duke]

Hi,I have just bought an S3.It was rebuilt some years ago,& has stood for years.The lights,indicators,& brake lights don't work,but the hazzard warning lights do.Fuel gauge not giving a reading.I am sure there will be many more questions,as I have collected it,& driven it home,using good,old fashioned ,hand signals.

[mgcjag]

Check all the fuses....clean up the fuse holders they often cause problems....do you have a wireing diagram..see knowledge base section if not....Steve

[Neil Duke]

I have got a wiring diagram.I will be checking connections,& fuses at the weekend.Just wondered if this was a regular problem.Thank you.

[abowie]

A car sitting for 5 years might well develop gremlins; Lucas was the Prince of Darkness, after all.

I'll preface this by saying that I'm not very experienced with S3 cars.

The fuses are found behind the central drop down instrument panel. They are numbered 1 to 8, starting top left downwards for 1 - 4, then 5 -8 are top to bottom right.

Headlights/high beam are fuse 1 and 2 respectively.

Indicators and brake lights from fuse 6.

The fuel gauge power comes from fuse 7 via a 12/10v voltage regulator mounted on the centre drop down panel.

So if it's fuses, at least half of them don't work. Which is a bit odd.

Other things to consider.

Fuel gauge. First check to see if the water temp gauge is working. It gets 10v power from the same voltage regulator and if it works, your problem is not the 10v supply to the fuel gauge. Then check that the fuel sender unit actually works; it's in the top of the tank under the boot boards. It should change resistance when the float is moved up or down.

The lights and indicators all go through the indicator switch, so many of your problems may actually be with it.

I've also sent you a private message.

[abowie]

[Neil Duke]

Having a quick look last night,I found this in-line fuse holder to have the wrong type of fuse in it.Can you tell me what this one is for?& what size fuse it should be?Thanks for your help.

[Neil Duke]

The lights and indicators all go through the indicator switch, so many of your problems may actually be with it

This sounds promising

[driver]

Hi Rob Gill here,
might be worth checking/cleaning as many earth connections as possible.
All the best.

(ref other subjects you cant beat a good s3 ! )

[abowie]

what size fuse it should be

Again, not a S3 expert but looks aftermarket...

[vee12eman]

Hi.

Should be a 35A glass fuse. Note the rate of glass fuses is different from the actual rate, but they are normally described by the blow rating, from memory, 35A fuses have a 17A continuous rating.
It’s not an after market fuse, correct for S3.

Regards,

Simon.


Edit:

Here’s the correct fuse:

[mgcjag]

The inline fuse with 2 brown wires is for the horn....there is another fuse that powers sidelamps, brake lamps, numberplate lamp, all of the panal lamps fead from the Red Black of the headlamp switch .......The service manual and wireing diagrams should be your best friends now you have a S3...they will be invaluable.....Steve

[Neil Duke]

Thanks guys,I will take another look,when I get back from work.

[davef]

I believe that the fuse on the frames also powers the fans. I had that blow on a trip to France when one of the Fans let go, took 20 mins in the queue for the tunnel to find the problem, minutes to fix, lucky I had a spare.