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TR2/3/3A Quick Overdrive Wiring Question


Luke Skywalker
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I only have a wiring diagram for a TR4 for the overdrive wiring. What gauge are the wires coming off the ignition switch and AMP meter that go into the relay and on a TR3 does the brown wire get it's power from the amp meter? I have 16 gauge and started to wire mine and noticed that the OEM yellow purple wire is probably 10 gauge so I got concerned about my 16 gauge wire. Also how are the wires routed from the transmission to the relay? I also was planning to connect the white wire to the + side of the starter switch as the ignition switch terminal already has 3 wires in it. Any problem here? This is a A type.

Thought I was going to wire up my overdrive tonight but went to get the relay out of the donor TR6 and there was none. They must have wired it directly through the switch. Anyway is there a aftermarket option? Thanks


I think you can see some of your answers in this photo:



Luke Skywalker
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Ok good diagrams but does anyone know the size of the wire? Also do the wires get routed through the transmission tunnel. So would I have to drill a hole and insert a grommet or do they get routed around the back of the engine and through the fire wall?

I am making my own harness to the relay and that is why I'm concerned about the size of the wires.


Darth Vader
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Jedi Warrior
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Sorry for the poor quality earlier. I'm trying again because I added an in-line fuse to the original schematic. The high load on the solenoid is only for a miilesecond but the pull-n coil has been known to stick which will fry the solenoid. The fuse doesn't prevent it from malfunctioning but will prevent the destruction of the solenoid. The size answer is: 16ga will be fine.
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