Rear light
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Vespa sprint1967
Joined: 13 Apr 2020
Posts: 9
Location: Christchurch
Fri Apr 30, 2021 1:43 am 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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GL, PK, PE200 with hack, Sears Rust Badge
Joined: 24 Apr 2012
Posts: 995
Location: Deep in the heart of Texas
Fri Apr 30, 2021 6:46 am quote
Did you change the brake switch on the Sprint to 12v. Prob need to change the handlebar switch for the horn to work.
Member
Vespa sprint1967
Joined: 13 Apr 2020
Posts: 9
Location: Christchurch
Sat May 01, 2021 1:14 am quote
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,
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GL, PK, PE200 with hack, Sears Rust Badge
Joined: 24 Apr 2012
Posts: 995
Location: Deep in the heart of Texas
Sat May 01, 2021 3:05 am quote
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.
Member
Vespa sprint1967
Joined: 13 Apr 2020
Posts: 9
Location: Christchurch
Sat May 01, 2021 9:02 am quote
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,
Enthusiast
1959 Allstate w P125x Engine
Joined: 29 Nov 2020
Posts: 74
Location: Los Angeles
Sat May 01, 2021 10:00 am quote
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.
Addicted
GL, PK, PE200 with hack, Sears Rust Badge
Joined: 24 Apr 2012
Posts: 995
Location: Deep in the heart of Texas
Sat May 01, 2021 10:03 am 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?
Ossessionato
76 Sprint V, 63 GL, 62 VBB, 05 Stella
Joined: 16 Jun 2011
Posts: 3201
Location: Nashville
Sat May 01, 2021 11:20 am 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."
Member
Vespa sprint1967
Joined: 13 Apr 2020
Posts: 9
Location: Christchurch
Mon May 03, 2021 4:29 am quote
Thanks for your replies, I will get a few pictures together,
Member
Vespa sprint1967
Joined: 13 Apr 2020
Posts: 9
Location: Christchurch
Mon May 03, 2021 5:03 am quote
Hi guys I have managed to get a few pictures together















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