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Tr4 electrical help

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jefftriumph Avatar
jefftriumph Jeff F
Buffalo, New York, USA   USA
Replaced all lights, and the headlight switch(corroded) Everytime in turn the lights on the fuse blows?

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Trike4 Avatar
Trike4 Marcus G
Brighton, Michigan, USA   USA
1963 Triumph TR4
1963 Triumph TR4 "Trike"
Time to get the Ohm meter out and start isolating the problem. Get a wiring diagram and understand the circuit. Don't forget power runs through the foot operated Hi/Lo beam switch. Might have mis-wired the Hi/Lo switch.
Disconnect the headlight wiring and battery. Turn the multimeter to Ohms and insert one lead into the power wire and ground the other. If you are seeing low resistance (Ohms) you are shorting to ground on that wire.
Very likely a spade connector is touching ground near a switch (main light or hi/lo)

jefftriumph Avatar
jefftriumph Jeff F
Buffalo, New York, USA   USA
The high beam switch is disconnected, would that be the cause? Thank you for your knowledge!!

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TR3driver Randall Y
Confusion, Los Angeles, USA   USA
In reply to # 1489327 by jefftriumph The high beam switch is disconnected, would that be the cause? Thank you for your knowledge!!
Not unless the stock wiring has been changed. The original setup only has a fuse for the tail, marker and dash lights. And usually, a short in the dash lights will burn up the rheostat rather than blowing a fuse.



Randall
56 TR3 TS13571L daily driver
71 Stag LE1473L awaiting engine rebuild
7? Stag awaiting gearbox rebuild

nicodiaz Roberto Diaz
Oceanside, CA, USA   USA
In a Tr4a, if the high beam 12volts incoming wire ( U ) is disconnected, hanging loose, and touching ground, the fuse would blow when the head lights switch is turn on.

TR3driver Randall Y
Confusion, Los Angeles, USA   USA
In reply to # 1489428 by nicodiaz In a Tr4a, if the high beam 12volts incoming wire ( U ) is disconnected, hanging loose, and touching ground, the fuse would blow when the head lights switch is turn on.

Which fuse is that, and why? According to my diagram, there is no fuse in the path to the U wire.



Randall
56 TR3 TS13571L daily driver
71 Stag LE1473L awaiting engine rebuild
7? Stag awaiting gearbox rebuild

nicodiaz Roberto Diaz
Oceanside, CA, USA   USA
Randall,
You are correct. For safety reason there never was a fuse in the lighting circuit. I misread my schematic with the changes I made to interlock headlights with ignition switch.
Thanks,

Oceanside, Ca
1966 tr4a irs

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