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Overdrive Electrics


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Hi All

Bit of a query with fitting my new(ish) overdrive harness.

Now the wiring diagram for the overdrive is pretty simple.

post-13051-0-00868200-1524179215_thumb.png

But the reality looks a little more complex to me.

My A type has three switches mounted on the GB top cover, presumably the various on/off switches to stop engagement at the incorrect times, ie reverse and 1st.

So I need to install my Autosparks 863 overdive harness, pictured, and 865 overdrive relay harness. The relay end of the relay harness is simple enough but I’m not sure about the gearbox end.

Does anyone have any pic s or diagram of which colour wires go to which switch and in what order and I’m assuming the feeds from the relay go to one of the switches (first one) on the gearbox but not sure and need a little guidance.

Thanks

Keith

post-13051-0-27185300-1524178913_thumb.jpgpost-13051-0-03113800-1524178925_thumb.jpg

 

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Keith,

 

As per Tom's diagram, you should have a relay on the A type so the diag on your orig post is not correct. Also of concern is that you appear to have wired up the reverse switch for the overdrive, this will wreck your overdrive if you reverse. The reverse switch is to turn on the reverse lights not to stop you engaging the overdrive when in reverse. If you think of the overdrive switches as enablers not inhibitors it's easier to understand. So when 2nd, 3rd or 4th are selected that moves the selector rods that then operate the switches, so the switches short out and provide a circuit from the local eth (Black wire under a bolt on gearbox) through the yellow to operate the relay. The relay then provides the power back to your overdrive solenoid.

SwitchLoc.JPG

 

Regards,

 

John

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Hi Tom and John

Thanks for the feedback, your comments have made me look harder at the info I’m using.

My car is a 72 so I’ve been using the Advance Autowire wiring diagram for a 72 car, which is where I copied the overdrive diagram from, I thought it looked a little short on detail, hence the question. My car is pretty early 72 and I’ve looked now at the 70, 71 diagram and that looks much more like it. Not sure when the different wiring diagrams are applicable from, maybe model year, so I’ll be referring to the earlier wiring diagram as the overdrive diagram looks more like Tom’s.

Useful to think of the switches as enablers not inhibitors it does make it easier to understand. So I’ll go have a play and see where I get. Wiringing it up wrong is no prob, its hasn’t turned a wheel in XX years and I’ll be lucky if it does this year.

I’m sure I’ll still have the odd question as I seem to have a few to many snap connectors and not 100% sure on those but I’ll scrutinise the wiring diagram.

Thanks

Keith

 

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