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Tr4 electrical help

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jefftriumph Avatar
jefftriumph Jeff F
Buffalo, New York, USA   USA
Still no headlights. The dimmer switch was corroded and disconnected. I replaced
that. Same thing blows the fuse the minute I turn the headlights on. No obvious breaks in the harness. There is a curious round green thing on the left footwell above the dimmer switch to the left. 4 green wires go to it?? Any ideas what this is? Any advise on the lights. Turns, rears, stops and rear turns all work.

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Trike4 Avatar
Trike4 Marcus G
Brighton, Michigan, USA   USA
1963 Triumph TR4
1963 Triumph TR4 "Trike"
That curious thing may be the signal flasher.

Still unclear what fuse you have in the head light circuit. There is a fuse that feeds all the red wires - tail, parking, license plate and another fuse for green wires - dash gauge lights, signal, stop lamps.

Regarding headlights - you might want to get some small jumper wires and a 12 volt battery and with your car battery disconnected - try powering one headlight at the bullet connectors near the radiator duct. Repeat for both hi/Lo beam. If they light up - that eliminates that part of the wiring. Connect back up.
Now disconnect the headlight wires (blue/white, blue/red) from the dimmer switch and try powering the lights. If they work then connect back up.
Disconnect the blue wire from the light switch on the dash and try powering the lights there. If they work then connect back up.
But if your tail lights work it means there is power to the switch. But it is a two position switch. One click out and you have parking lights. license plate, tails. Another click out and you should have headlights.

My suspicion is the foot dimmer switch. It is very easy to have spade connectors touch metal if the rubber gasket is not right.

jefftriumph Avatar
jefftriumph Jeff F
Buffalo, New York, USA   USA
There is a separate flasher unit under the dash. The dimmer switch is brand new. The fuse I'm referring to is the fuse for all the lights etc. That is the one that blows, where the red wire connects

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Trike4 Avatar
Trike4 Marcus G
Brighton, Michigan, USA   USA
1963 Triumph TR4
1963 Triumph TR4 "Trike"
Something is mis-wired. The headlights shouldn't run through a fuse. If the tails, parking and license lamps work (and they do run through the red wires coming from that fuse) something is wrong. Attached is a wiring diagram for a TR4. The path for the headlights is from the voltage control box to ignition switch, to light switch, to dimmer switch, to hi or lo beam and then to ground. A short circuit would be 12 volts passing to ground before reaching the headlight filament.

You could disconnect the headlights at the bullet connectors near the radiator duct, pull the light switch on - nothing should happen. With a volt meter you should see 12 volts at the wire which would connect to the headlights.


Attachments:
TR4 wiring.jpg    40.1 KB
TR4 wiring.jpg

jefftriumph Avatar
jefftriumph Jeff F
Buffalo, New York, USA   USA
That's give me something to work with. Thanks for your insite.

ric350 Avatar
ric350 Jim Feeney
Holmdel, NJ, USA   USA
Jeff, just FYI. Last year DesertTR and I confirmed there were discrepancies between the Tr4a wiring diagrams (Autowire and the shop manual), and what we actually had in our cars. One that we found was a wire from the light switch to the headlight dimmer switch pole that goes directly to the headlights (as I recall it's for the headlight flash function). I don't know if that may also be the case for the Tr4, but it may be worth a look. It was a tedious job going through the wiring of my car with a test light, but at least now I have an updated/correct diagram (at least for my car).

Jim

jefftriumph Avatar
jefftriumph Jeff F
Buffalo, New York, USA   USA
Ok, so the red/green wire that goes from the fuse box to the lighting switch is melted at the connector. That maybe the problem. I need to chase it after work

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jefftriumph Avatar
jefftriumph Jeff F
Buffalo, New York, USA   USA
Thanks Jim

trrdster Avatar
trrdster Wayne Tate
Spencer, NC, USA   USA
Jeff, the green wire connection in the upper part of the passenger foot well is the voltage stabilizer for the gauges.
On later cars TR6 and Spitfires they placed it on the back of the tack or speedometer.



Wayne
1970 TR6
2000 Jaguar XK8
1949 Triumph Roadster 2000
1978 Spitfire (rust victim)
1971 GT6 (tarp covered for 12 years, rusted inside out)
1980 Spitfire (getting all the good GT6 parts, all poly suspension and Spax shocks)

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jefftriumph Avatar
jefftriumph Jeff F
Buffalo, New York, USA   USA
I'd like to thank everyone for their insite and help. I've got headlights, and everything but left side tail and stop light. Down to a short in one red wire. Ran out of time tonight, but I intend to finish tomorrow and weather permitting take her out

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