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Vespa sprint1967
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Location: Christchurch
 
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Vespa sprint1967
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Location: Christchurch
UTC quote
Can anyone help please, just put a px engine into a sprint frame, the back light seems to work the wrong way, when the wires from the switch touch the light comes on when apart it's off, I have obviously got the wiring wrong somewhere, but the other lights seem ok,
If anyone can help I would much appreciate it as I haven't much hair left 👍
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Molto Verboso
GL, PK, PE200 with hack, Sears Rust Badge
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Molto Verboso
@rowdyc avatar
GL, PK, PE200 with hack, Sears Rust Badge
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Location: Deep in the heart of Texas
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Did you change the brake switch on the Sprint to 12v. Prob need to change the handlebar switch for the horn to work.
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Vespa sprint1967
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Location: Christchurch
 
Member
Vespa sprint1967
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Hi yes I changed the switches, even without the rear brake switch fitted, if the wires touch the rear light comes on, I have something wrong with the wiring, I am correct in thinking when the wires are fitted in the switch the light comes on when the contact is broken,
@rowdyc avatar
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Molto Verboso
GL, PK, PE200 with hack, Sears Rust Badge
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Posts: 1346
Location: Deep in the heart of Texas
 
Molto Verboso
@rowdyc avatar
GL, PK, PE200 with hack, Sears Rust Badge
Joined: UTC
Posts: 1346
Location: Deep in the heart of Texas
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There's sometimes a need to rewire sections of the harness when converting to 12v. Find your bike original wiring diagram at scooterhelp and search this forum for 12v conv. There are many post with examples and new diagrams for 12v conv all around here.
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Member
Vespa sprint1967
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Location: Christchurch
 
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Vespa sprint1967
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Location: Christchurch
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Well I have put a new harness in the scoot, do you know if my question about when the wires are in contact with each other the light is off,
@ray8 avatar
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Molto Verboso
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Molto Verboso
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Rog64 wrote:
Hi yes I changed the switches, even without the rear brake switch fitted, if the wires touch the rear light comes on, I have something wrong with the wiring, I am correct in thinking when the wires are fitted in the switch the light comes on when the contact is broken,
You have the wrong switch. One maintains contact until the pedal is pressed. You need the one that does the opposite.
@rowdyc avatar
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Molto Verboso
GL, PK, PE200 with hack, Sears Rust Badge
Joined: UTC
Posts: 1346
Location: Deep in the heart of Texas
 
Molto Verboso
@rowdyc avatar
GL, PK, PE200 with hack, Sears Rust Badge
Joined: UTC
Posts: 1346
Location: Deep in the heart of Texas
UTC quote
Rog64 wrote:
Well I have put a new harness in the scoot, do you know if my question about when the wires are in contact with each other the light is off,
Depends on what light. There is a brake light and a tail light. The tail light will come on when connected and motor is running. Brake light runs off the brake switch. If you didn't get a 12v wiring harness you will need to rewire the brake switch. The original switch was wired with a power wire in and a ground wire. The 12v switch needs a power wire in and a power wire out to brake light. If you didn't get the right harness the brake light and tail light will stay on.

Being that you have a 1967 Sprint can we see pictures?
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Lucky
76 Sprint V, 63 GL, 62 VBB, 05 Stella, 66 Smallstate, 79 P200E, 66 Lammy S3
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Lucky
@chandlerman avatar
76 Sprint V, 63 GL, 62 VBB, 05 Stella, 66 Smallstate, 79 P200E, 66 Lammy S3
Joined: UTC
Posts: 9925
Location: Nashville

69 Days Since Last Explosion
UTC quote
Assuming that you had the old 6v Balanced AC system, the brake light worries by shorting the brake light circuit to ground, so the switch was Normally Closed. When you press the pedal, it breaks the short to ground so the path of least resistance of now through the bulb.

If you've gone to a 12v system, the circuit will be Normally Open, so when you press the pedal, it closes the circuit and power can flow to the light.

Which is a lot of words to say "you need to get a different brake switch."
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Member
Vespa sprint1967
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Location: Christchurch
 
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Vespa sprint1967
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Location: Christchurch
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Thanks for your replies, I will get a few pictures together,
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Member
Vespa sprint1967
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Location: Christchurch
 
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Vespa sprint1967
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Location: Christchurch
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Hi guys I have managed to get a few pictures together
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