Indicator issues

[adrian]

Ok so I have a problem with the indicators on my px, the work fine with the lights off, but when the lights are on they don't work. Any idea what it could be? Thanks Adrian

[uncle ernie]

Simple version



The current generated by the flywheel/stator goes to the regulator, and then on to the indicator relay. From there it is sent down two wires, one carrying current to power the rear indicators, the other the front. When the two wires reach the handlebar switch each is split, giving four wires in total, and these run to the indicators.



That's simple enough to visualise - One to two to four, with the two taking it in turns to carry the current as it gets switched by the relay. This explains why Vespa indicators flash alternately rather than together, ensuring that there is a constant 21w load on the system, rather than 0W-42W-0W-42W..



Slightly more descriptive version



The power for the indicators comes from the regulator, a silver, ribbed, hexagonal device located under the left hand panel and behind the spare wheel (and battery if fitted). If you examine this, you'll find a wire running to the small square (often green) block sitting in the same area. This is the indicator relay.



The relay has three connectors, and the wire from the regulator runs to the most central pin. A simple description of how the relay works is to imagine a pendulum inside, swinging from side to side and contacting the two remaining pins in turn.

These other two pins have wires which run up the frame to the indicator switch. From here, the current is directed by the switch to the four wires which run to the indicator bulbs.



Fault finding



Because of the simplicity of the system, fault finding is pretty simple.



If all the indicators are out, then the chances are that the wire between regulator and relay has become broken or dislodged. Check and plug back in/replace as needed.



If both indicators at one end have failed, then check the wires between the relay and the switch. You may need to do a continuity test to do this properly (See end). 90% of problems like this are on this part of the circuit.



If both indicators on one side have failed. This is very rare, and I've only ever known it being down to a damaged switch, generally with the wiring being pulled tight and pulling away.



If only one is out, then the problem will be somewhere between switch and earth.



Simple as that!





All that said, there are a few predictable and regular problems.



Firstly, if you get any problems, always check the bulbs. I know it sounds obvious, but the frequency in which you see people chasing all sorts of issues for a blown bulb...

Next are the panels - the connectors at the front can get filled with gunk, making for a poor connection, and the earthing connection through the spring on the top can get similarly affected. Keep them clean and a lot of problems can be avoided.

Finally, front indicator wires are very vulnerable. Any problems at the front, check the two wires that attach to each bulb, these are easily dislodged.





Continuity testing

The easiest way to check for broken wiring is a continuity test: Grab a cheap electrical meter and set to resistance (ohms - the little picture that looks like a bridge!) and touch one probe to each end of the wire you need to test. Hopefully the reading will be zero ohm, or near enough. Anything higher than a small amount suggests that there is an issue with a broken wire

[adrian]

Thanks for that, but still none the wiser as why indicators only work with lights turned off, unless it's the stator , will put my spare on at the weekend and see if it makes a difference

[kru251]

Poor earthing accounts for a myriad of issues.......
Check wiring thoroughly before changing the stator.

[bucko64]

I have a 1983 mk1 PX125E, it's a 'crossover' model and has the wiring/switchgear the same as P200E. I am having trouble with my indicators, both rear ones are not working. After studying the wiring diagram and reading uncle Ernie's good description above I think the fault must be on the red wire between the Relay and the JB, or the JB to the switch, but before I get back to that I am puzzled by how the indicator light in the headset works, it gets a permanent 12V on the grey wire but also what I assume to be 12V on the red wire from L2 on the relay. How does that work??? Perhaps someone can also check and tell me if their headset flashes in time with the front or rear indicator? Thank you.