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Hi, new member to the site. Over the years I’ve found so much great reliable info, so thanks 👍

Unfortunately I haven’t been able to find anything on my latest issue. What I’m experiencing is really doing my head in 🙄 The bike won’t start. It won’t throw the starter motor. I can hot wire it by bridging the positive across the Relay mount. I’ve tested the relay and also bought another and both work. I’m getting a clicking at the relay when I hold the brake and press the stater button. I have a feeling that the second small pin in the relay isn’t doing it’s job. It’s not going to ground or providing power. I’ve looked wiring diagrams and seen it possibly goes to a fuel injection relay, however I’m not sure where to locate it. Any help will certainly be appreciated. My wife uses the bike daily as her commuter and right now she is very stressed her baby is out of action
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In my experience, the number one cause of not starting is a weak battery. "It won’t throw the starter motor" sounds like this could be the case here. Can you have the battery load tested? Also, look for dirty or loose battery terminal connections.
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Thanks for the reply. It starts fine with plenty of power when I bridge the wires across the relay mount. I started it at least a dozen times whilst investigating the second small wire from the relay. I’m suspecting there’s another relay/switch somewhere that powers this wire during the start process
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"I’m getting a clicking at the relay when I hold the brake and press the stater button." This tells me that the relay coil circuit (the "small wires") is working. Are the contacts in the relay socket dirty or corroded?
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"...it possibly goes to a fuel injection relay,"

Doesn't an LX have a carburetor instead of FI?
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It’s an EFI. Any idea where I might find that relay?
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No.
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Hey,
I'm the new guy.
I have a friend with a busted vespa so i came here for info.
Usually, I help out with electricals on a Kawasaki forum.

Anyway, to your problem.

Grab your meter DC V
key on/ ignition on
Black probe on negative battery post(post being the metal part of the battery)
Red probe on the positive battery post
note voltage
(just checking battery voltage for a reference)

push starter button
note voltage
(voltage should drop no more than 9.0V)

move your red probe to the battery side of the starter relay post (big cable coming from battery)
note voltage
push starter button
note voltage
(voltage should drop no more than 9.0V)

move red probe to other side of starter relay(big cable at relay going to starter)
push starter button
note voltage
(the meter should be 0.0V before you push the starter button going to no less than 9.0V when the button is pushed)

find the wire that is coming from the starter button to the relay
red probe on that wire
push starter button
note voltage
(wire should be 0.0V before you push the button going to 12.0V when pushed)

turn on your phone
find an app for a magnetic compass(unless you have an analog one)
put the compass/phone close to the relay.
push the starter
compass needle should swing with starter relay activated.
The relay is an electromagnet. If the magnet is working, then the needle will swing.

Judging by you bypassing the relay it would appear something is wrong in the relay area.
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Yep getting great voltage at relay. Same as battery. Yep it is a magnetic relay. I’ve had the cover of the relay. This area is working as it should. If I run a positve wire to the side of the relay I’m not getting power or a ground from it will start. The issue is this wire to the relay. It should power only momentarily as the brake/start switch are engaged. Hence why I’m thinking there’s another relay somewhere 🤔
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or there could be a break in the small wire coming from the starter button.
I'm not sure if the starter button sends a ground signal to the relay or a positive signal.

The other thing that could be wrong is the metal bar inside the relay connecting the battery to the starter when the magnet is on could be damaged.

Check the voltage on the small wires going to the relay when you push the starter button.

there is no other relay. Just the brake switch and the start switch. Check to see that the relay is getting +12V when you push the start button. It will be on one of the small wires going into the relay.
brake switch is 9
start switch is 8
relay is 6
starter is 7
battery is 5
Forum member supplied image with no explanatory text
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Veni, Vidi, Posti
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Assume you've checked the kill switch and the brake light works?
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I’ve checked continuity from starter / brake to relay, all is good. The Other wire on your diagram shows it goes to ground. On a diagram I’ve seen its showing it going to a fuel injection relay.
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post a screen shot of that fuel injection relay schematic if you can.

Continuity is not a good way to check for wire condition. Voltage drop is better.
You could have one tiny strand of a 50 strand wire give you continuity.
Whereas voltage drop will show that you have a big voltage drop within that section of wire.

Which year and model do you have exactly?

Does your brake light work as znomit had asked?

I've found another schematic. The computer supplies the ground on that schematic.
Not sure what the conditions are for supplying that ground signal, but if the relay is clicking then the relay is seeing that ground signal.

Take off the cover of the relay. Push the starter button. If the relay magnet pulls in the switch and nothing happens, your starter relay may have arced the contacts inside so badly they won't conduct electricity.
This makes sense if you jumpered the starter relay terminals to get the starter to turn. This means you need a new relay.
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I reckon I’ve found the problem. Within the ECU. I’ve done checks on relay, starter, switch, and the wiring. Wiring from starter goes to ecu, then from ecu to relay https://manuals.wotmeworry.org.uk/Vespa/LX125-150ie/LX125-150ie%20Wiring%20Diagram.pdf
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But you mentioned you are hearing a clicking at the relay.
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yep, that is the other schematic that i have found.
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F64 wrote:
But you mentioned you are hearing a clicking at the relay.
Correct, however it’s not switching it. It’s hard explain. It’s positive however turns negative once a positive from the other terminal is powered. ECU controlled in someway
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you will not hear a click at that relay if the computer is not sending a ground signal to the relay.
The magnet will not activate.
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It’s clicking. But The relay isn’t grounding-via the opposite wire. I’ve done test on test. I can start the bike by putting my pointer pliers in the relay mount slots from battery to starter. I’ve tried 3 relays. The original and 2 new ones.
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grab your meter
DC V
key on/ignition on
red probe at pin 24 at computer(orange/blue wire) do not disconnect connector.
black probe on battery negative post
note voltage

press starter button
note voltage

move red probe orange/blue at relay
note voltage

press starter button
note voltage

move red probe to orange/white at relay
note voltage

press start button
note voltage
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Thanks, I’ll get onto tomorrow now. I’ve had enough for today. Beer o’clock for me. Appreciate your help. I’ll let you know how I go. Damn ECU ain’t cheap. I’ll be Hotwiring it I have to 👍🍻
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very good.
4:00am here.
time for bed
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6:15pm here in Australia 🇦🇺 👍
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I’ve added my voltage in at each step.
F64 wrote:
grab your meter
DC V
key on/ignition on
red probe at pin 24 at computer(orange/blue wire) do not disconnect connector.
black probe on battery negative post
note voltage. Voltage @.04

press starter button
note voltage. Voltage @ 12.2

move red probe orange/blue at relay
note voltage. Voltage @ .04

press starter button
note voltage. Voltage @ 12.2

move red probe to orange/white at relay
note voltage. Voltage @ 11.8

press start button
note voltage. Voltage @ 11.65
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ok,
something weird is going on.
just by having your key on it seems the relay is on.

You push the button and the computer disconnects the ground.

Have you done any work to the bike lately?
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Absolutely nothing.
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DaleR wrote:
I’ve added my voltage in at each step.
F64 wrote:
move red probe orange/blue at relay
note voltage.
Voltage @ .04
F64 wrote:
press starter button
note voltage.
Voltage @ 12.2
My bold. Therein lies a problem. That relay coil should be grounded by the ECU when it's happy for you to start, i.e. the voltage should remain very small, not 12V.

See: https://manuals.wotmeworry.org.uk/Vespa/LX125-150ie/LX125-150ie%20Wiring%20Diagram.pdf
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check your fuses but use this method

key on/ignition on
meter DC V

black probe on negative battery post
red probe positive battery post
note voltage

move red probe---probe both sides of each fuse
voltage should be close to battery voltage
if there is a big drop...more than 0.5 they you may have a connection or fuse issue.
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well the weird part...your relay should not be seeing 12V if the button is not pushed.
It's like you have a stuck switch or short.
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Just probed all fuses. Got 12.85 at battery. Fuses close to battery 12.5. Fuses at front if bike get 12.4
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is your immobilzer lamp off when you try to start the bike?
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Yeah it’s off. There’s a purple wire that comes from the start switch to the ecu I reckon it’s something to do with it maybe inside ecu 🤔
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it's hard to read, but i wonder if this is closer to your schematic.
what are the wire colors going to the starter relay?
Forum member supplied image with no explanatory text
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check continuity of your starter switch.
this circuit is pretty strange, but it explains why i see 12v at the relay.
The brake switch sends 12v to the relay and when you push the starter button that sends 12v to the computer. The computer at that point may send a ground to the relay.
⚠️ Last edited by F64 on UTC; edited 1 time
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Wires are white/black which comes from brake switch it’s positive when brake depressed. Other wire from switch is purple. It’s positive at ecu when pressed whilst holding in brake lever. 12 volts
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Crazy stuff! I took the slack out of the throttle cable the other day. I’m tippin it’s mucked with the throttle sensor. I just loosened it off and it’ll start. It must’ve been like in a touch and go position 😡
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take a look at this.
I'll try to figure out what is going on while you look at it
Forum member supplied image with no explanatory text
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I’ve got it starting. I’d adjusted the slack in throttle the other day, it was running afterwards. It must’ve been really close to not running and perhaps it’s done something with the throttle sensor. I loosened it off it and what ya know. It’ll start. I’ve gotta thank ya mate for all your time and knowledge. I’ve learnt a lot quickly I’ve gotta say. Truly thank you so much. I owe ya a beer or 10 🍻
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damn!!!!!!

good to know!
good job!
definitely a time for a drink

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