Vixen electrics
Discussion
If ignition light comes on with starting and becomes brighter with revs but the ammeter shows charging what does that mean? All alternator wiring seems OK. The rev counter packed up some time ago. My plan is to have the dash off and have a rummage.
Offers of advice or consolation invited.
Offers of advice or consolation invited.
I would suspect the alternator. There should be two thick and one thin wire coming from the alternator, the thin one should go to the ignition light.
You seem to be re-commissioning, l would recomment the Haynes Auto electrician book
http://www.amazon.co.uk/The-Haynes-Electrical-Syst...
It might help.
You seem to be re-commissioning, l would recomment the Haynes Auto electrician book
http://www.amazon.co.uk/The-Haynes-Electrical-Syst...
It might help.
Before you go under the dash Remove small wire from alternator and using a small bulb or test light take a positive feed to the bulb then to the alt with not running bulb should light with it running light off as the alternator should remove the earth for the bulb. Sounds like alt as still can charge with faulty light circuit. Hope that helps. Richard
Not arguing with any of above, but weird things like this can be caused by dodgy earth returns, and the TVRs suffer a LOT from this kind of thing, being GRP. Check that there is no voltage between the dash earth wire (use the back of one of the gauges) and the engine block when car is running.
A mate came over and I helped him out with some bulding stuff - he looked at the Vixen and had exactly the right alternator lying around so I tried it and bingo housey housey all is OK with the world, we have charging and the right light at the right time. All very odd but sorted. Going to fit another rev counter this evening and see if the good lord is still shining on me for once.
As Adrian said above - remember that there are different types of tachos, in the way they are triggered.
Info -
The oldest designed ones were current triggered, and were wired in series with the coil. This type will NOT work if you have an ignition amplifier, contactless conversion etc. This type were in Cortina Mk1 and Triumph saloon Mk1 and that sort of era. They typically had a little wire loop on the back of the tacho (not all of them though)
The later designs used a voltage trigger, which should work on pretty much everything - it expects a short 12v pulse and so can be wired simply to the +ve on the coil (the 'contacts' equivalent) some of the ignition amplifiers for contactless systems have a separate tacho connection.
Some of the Bosch tachos require a high voltage pulse, and do not always work with some amplifiers, but I've only seen those a couple of times....
Info -
The oldest designed ones were current triggered, and were wired in series with the coil. This type will NOT work if you have an ignition amplifier, contactless conversion etc. This type were in Cortina Mk1 and Triumph saloon Mk1 and that sort of era. They typically had a little wire loop on the back of the tacho (not all of them though)
The later designs used a voltage trigger, which should work on pretty much everything - it expects a short 12v pulse and so can be wired simply to the +ve on the coil (the 'contacts' equivalent) some of the ignition amplifiers for contactless systems have a separate tacho connection.
Some of the Bosch tachos require a high voltage pulse, and do not always work with some amplifiers, but I've only seen those a couple of times....
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