Jim Davis wrote:
> I am installing a handbrake on one of my '75 TR6s with a provision for
> a handbrake light switch. I purchased your incredible Electrical
> Maintenance Handbook (let me add my thanks to the many you have already
> received) and it appears from looking at the '76 schematic that all I
> need to do is splice a wire from the handbrake switch into the
> black/purple wire between the existing lamp and the PDWA switch. Is this
> correct? It is a little confusing to me as the '76's have a purple/slate
> wire from terminal C4 on the "bulb test relay" and mine doesn't.
Jim,
That will work, but you won't test the oil pressure warning lamp if the
handbrake is on. As it is now, when you turn on the key, both lamps are lit
to show you that the bulbs work. If you wire the handbrake switch as you
suggest, both sides of the oil lamp will be at ground when the handbrake is
on and the oil pressure isn't up to normal.
I suggest you rewire the circuit to match the 76, except leave off the
purple/slate wire from the relay. This consists of moving the black/purple
wire from the oil lamp to the white wire side of the brake lamp. This is a
better setup anyway, as both bulbs are fully lit when you turn the key on and
the handbrake is on. If you don't have the handbrake on after the
modification, the brake lamp won't be tested, so be sure to leave the
handbrake on while staring the car - a good habit to get into anyway.
You might want to change the b/p wire from the oil lamp to a white one to
prevent confusion later on, especially if you should sell the car. If you
don't want to change the wire, which could be a lot of trouble, just paint it
white. Or at least make a note of the discrepancy in the color code.
Dan
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