Sounds like you have some slightly corroded connections. The tacho will bounce if the connections are not clean metal.

Quote:Easy enough to test. Ignore the other intermittent problems and concentrate on this steady problem. Turn key ON engine OFF and check for 12V at the alternator T-connection.

Quote:The instrument panel voltage regulator only affects the temperature gauge and fuel gauge. Nothing else.

Also just reading through the wiki, if the regulator is broken would this effect the tacho?

If anyone would be able to help,

I have suddenly found that the charge light on the dash has come on and is staying on regardless of rpm. Yesterday the charge light began to come on occasionally while at the same time the tacho started to bounce and also stop working. Although today the tacho is working again, the charge light is staying on even though I haven't touched any wiring also when I turn the headlights on the headunit will turn off for a second and work again. Previously my headunit went it to protection mode which is caused by a speaker wire short which I have fixed if this has any connection to the issue?

At the moment I think that it is a wiring issue as I bought the car about 2 months ago and it had a new alternator installed before i got it and has been running fine although occasionally in the morning when it was cold the tacho would bounce around a bit until warm. The guy I bought it off said that he installed the tacho dash so would a wiring fault be causing the charge light to come on?

I will still test the alternator when I get my multimetre though

Any help would be great!