In a message dated 96-11-21 08:10:14 EST, you write:
<< My car was restored using the harness (loom) from Moss. The stop lights
have never worked. I do have a circuit tester but not a wiring diagram.
Could the switch be bad? I just don't wish to bleed the system to
install a new one.
>>
Steve, All TD's had Stop lights...in fact all MG's from at least 1933 had
them. Trouble shooting this circuit may be difficult without a diagram but
shorting the switch that is operated by the hydraulic pressure should make
the lights on both sided come on. You have to have the key on too as I
recall.
Early TD's had a 9 post regulator, later ones had a 5 post regulator and a
seperate fuse block. Which do you have? In any case the stop switch is fed
from terminal A4, which will have green wires attached. When you turn on the
key, you should have 12 volts at this point to ground. Now go to your brake
light switch, check the voltage there. There should be 12 volts on the green
wire side and zero on the other..
Short the switch, now there should be 12 on both. If you have a turn signal
relay box, it now gets complicated as the brake light circuit runs through
the relay box.
In any case after you short the switch, you should now have 12 volts on one
pin of the tail light sockets. If you don't , find the grouped plug
connectors somewhere there at the back of the car, pull all the connectors
clean them and lubricate with WD40 or silicone spray, then plug them back in
making sure they go right home.
If you have turn signals, or if the harness was the one for turn signals and
your car was not so equiped, then you are loosing the circuit at that point.
Only a wiring diagram is going to help you trace it if this is the problem.
I can fax you a copy of a wiring diagram if you wish. In retrospect, this
is your likely problem, a turn signal harness in a non turnsignal car.
Let me know if I can help further.
Cheers
Terry
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