My alternator is only giving out 11.7V at the battery, I had a spare so fitted that one in and voltage at battery still 11.7V with the engine running

Any ideas?

Griff
Hoping to make it to Stoneleigh on monday 2nd

Is the ignition light working? On some of the older alternator set-ups the light was used as the "exciter" to make the alternator charge.
Otherwise it's a trip to an old fashioned auto electrician to get one of yours tested (if they're old school they won't charge you (no pun intended )

Thanks Tim

Not sure where it is on the Triumph Dolomite dashbord, then again none of my panel lights are working at the moment

A colleague at work also suggested the earth connection might be a problem, so I'll take that route first.

It will be the dash light (exciter) as Tim said, needs to be working in order for the alternator to work, if you can't find the dash light on the Triumph cluster then install a new light in this circuit.

Good idea, I'll check that part of the circuit, can't work on it until thurday as I'm away from home.

Thanks

It's not a solution, but the alternator should self excite at around 7000rpm, if you are brave enough, it may be a way of seeing if it kicks the alternator into life. I'm sure you can get a cable ran through, or check that the lamp hasn't blown in the dash.

If all the lights in the dash have stopped working, then I would look at something common to all the lights (connector, ground connection etc)


Good luck

Checked the wiring today, I've definately got an Lucas alternator, but only two wires going into it

when most mini diagrams have three

One is a big thick brown one, the other thin brown and yellow and they both are joined at the starter solenoid
to the +12V feed from the battery. There is no sign of any other connector in the plug to the alternator either.

At this rate I'll be towing it to Stoneleigh, then drive the last mile into the showground.

I'n not sure what your set up is but the brown/yellow wire is the one that goes to the ignition light. I'm probably talking rubbish but I think that the ignition light gets its feed from the instrument panel and earths along this wire rather than the other way round which is what you might expect but maybe somebody could confirm this.

Yes RaymondH you are correct, the brown yellow is the exciter wire, it is a earth wire from the alternator warning light on the dash, i.e. dash light is live and the brown yellow connects to the alternator and once spinning earths itself.

As for the 3 vs 2 wire at the alternator, there are 2 large spade terminals and one small terminal, the large ones are for the charging circuit and the small one is the exciter, you can bridge the two large terminals together if you want but it won't effect the charging.

The saga continues...

I connected a 12v lamp in parallel into the original circuit, and the alternator gives 12.06v now which is an improvement and the dashboard lamp now is on all the time.

Any ideas?

The alternator lamp needs a positive feed to one side and the other side is the brown/yellow wire going to the alternator, the lamp should ignite only when the ignition is on but the engine is not running, as soon as the engine turns over and reaches a certain RPM the exciter will contact and turn the brown/yellow wire into a positive effectively turing off the light. At this point you should have 14 volts, if this is still not giving you a reading like this then I would assume the alternator is not functioning properly and needs servicing.