revtothelimit - motorbike forum

Like the heading says, I can't get the indicators to work on the black Falco I'm preparing for sale. I bought the bike from another member of the Falco massive, after he'd experienced health and divorce issues. The bike had been left in his ex's garage for 7 years or more and he wanted it to go to a Good Home. This was apparently me...

As expected, after that long a layoff a number of things needed attention. When I got round to the electrics, I replaced the horrid little AliExpress indicators that Pete had fitted with the originals and expected them to work. They didn't...

I suspected that this was due to the AliExpress ones being LEDs and needing resistors in circuit to work. Pete assured me this was not the case and that the OE ones should work fine, as the AE ones were a direct replacement. However this assurance was not enough to get them working...

My first suspicion was the indicator relay, so I swapped it out with a known good one from 'my' red Falco. No change - no workee. I then turned my attention to the switchgear, and gave the multi-connector block that interfaces to the main loom a good dose of looking at and liberally applied contact cleaner. Still no signs of life, so I went on ebay and snagged a s/h switch for a few quid. This also failed to get the indicators working.

It's worth mentioning here that the LH switchgear cluster controls lights (side, dipped and main beam) as well as headlight flasher, plus horn and indicators. All the headlight functions work correctly, the indicators don't. Neither does the horn, but the horn looks as if it's lived in the North Sea for most of its life, so a new one has been ordered.

It was now time to get serious and break out the multi-meter. This is where it got really weird. My cheapo multimeter has the usual voltage functions and also a continuity tester. I disconnected each two-pin indicator connector block in turn and tested continuity between the -ve battery terminal and the corresponding -ve pin on the connector block. All four displayed continuity and beeped at me. I then connected the -ve probe to the battery -ve terminal and, connected the +ve probe to the +ve pin on the connector block and activated the indicator switch to the appropriate side. All four +ve terminals indicated 12.5V. The horn checked out in similar fashion. It is worth mentioning that the 12.5V reading was solid; it didn't go off and on as an indicator would when in use. Is this significant?

So now I'm really confused. Everything tells me that the indicators should just work but they don't. WTAF? I've pretty much reached the limits of my investigative powers and the only thing stopping me from availing myself of KFB's pyro services is the fact that the bike isn't insured.

So does anyone have any special insights, or fancy testing tricks I can try? If not, then early in the New Year a van will be arriving at Griff's premises in Tamworth with a black Falco in the back...

I’m confused.

Do the Ali express indicators work?

Do the standard ones work if plugged into your bike?

mangocrazy wrote: Mon Dec 29, 2025 12:59 pm r fancy testing tricks I can try?

Put the AE ones back on, what happens then?

I'm pretty sure the AE indicators went in the bin months ago, so there's no going back. It's the standard ones that are not working.

Do the OE indicators work in isolation? Nothing mad like four blown bulbs?

OK so try them dead ones on a known working bike and try a known working indicator on the bike being worked on.
Until you know if the fault is with the indicators or the bike you're going nowhere

MrLongbeard wrote: Mon Dec 29, 2025 2:09 pm OK so try them dead ones on a known working bike and try a known working indicator on the bike being worked on.
Until you know if the fault is with the indicators or the bike you're going nowhere

Pretty much that simple really.

I'm fairly sure I tested the indicators fitted to the black Falco on the red Falco, but I can easily re-visit that test. I can't do it right now as the red Falco and I are in Sheffield and the black Falco is in Stafford, but I'll be back in Stafford early in the NY. I've tried so much stuff over a period of time that it becomes a bit of a blur trying to remember what I have and haven't tested. The multimeter tests were done last week, so that's fresh in the memory.

I have a set of OE indicators fitted to the side front fairings and another set of 'loose' OE indicators with leads and connectors that I use for testing, as it's much easier to check wiring etc. with the side fairing panels removed. The rear indicators are fixed to the standard mounting points. I've tried all of them in various combinations and none work, so it would be a pretty monumental coincidence if I had six blown bulbs.

mangocrazy wrote: Mon Dec 29, 2025 3:17 pm so it would be a pretty monumental coincidence if I had six blown bulbs.

It would, but as you've said you're getting 12 volts at the connector block I'd at least expect the bulbs to light solidly, well unless the fault is between connector block and the indicator.

MrLongbeard wrote: Mon Dec 29, 2025 3:31 pm

mangocrazy wrote: Mon Dec 29, 2025 3:17 pm so it would be a pretty monumental coincidence if I had six blown bulbs.

It would, but as you've said you're getting 12 volts at the connector block I'd at least expect the bulbs to light solidly, well unless the fault is between connector block and the indicator.

Yes, it's gone beyond a simple electrical problem and I think I really need to go back to first principles, test everything again and make notes as I go. I've seen numerous instances when troubleshooting IT systems that wrong assumptions were made early on which completely stymied the investigation. The 'oh it couldn't be that' kind of assumptions that bite you in the arse later.

As Mr Pirsig would have said, don't assume anything. Write down what you know and don't know, with ways of determining the latter. If you do it methodically, it will work in the end.....

I'd just test all the indicators hooked up to a battery just to eliminate them although it's unlikely they'd all fail. And if they're LED of course they're polarity sensitive.....

Standard incandescent bulbs in these indicators. I did wonder if there was a hangover from LED bulbs complicating things, but Pete assures me not. However I'm not taking that assurance as gospel - as you say, assume nothing.

Until you have a known good indicator that works in bike 2 but not in bike 1, we don't really know how to help.

You can troubleshoot every fuse, connector and wire there is... but if the indicators are not 100% known to work, how the fuck can you ever know.

For £500 plus expenses...

I'll be testing all the unproven indicators on the known good bike and will report back. At least we'll have a baseline to work from then.

KungFooBob wrote: Mon Dec 29, 2025 5:03 pm For £500 plus expenses...

I'm not sure yet whether it's worth insuring...

Put BMW badges on it..

Indicators are a simple circuit: power comes from a fuse, through the flasher relay, to the switch. It is diverted to either side or null, where either side means a pair of indicators and a dashboard light then earth. There's only this many places to look for 12v.
This gets a bit more complicated if there are hazard lights and marginally more complicated if there's a single dashboard light, but if you have a wiring diagram and a few minutes to work out what it's telling you, you should be fine.
If it was me and knowing only what I read here, I'd start at the flasher relay connector. If 3 pin does it have a good earth on the earth pin? Is it possible it was re-pinned for the aftermarket relay?

Actually, your multimeter readings might be important. It sounds like you can get power from the battery through the relay (it wouldn't pulse without load) to the switch to each indicator, but it can't get back to earth. The earth path is through the dashboard.
Does it have a single indicator lamp? If so, the PO would have had to fit a "diode mod" to make LEDs work, whether he remembers doing it or not. This frequently involves scotchlock connectors. Ideally you'd undo that to eliminate it from enquiries.
Also if it has a single dashboard bulb and that has failed, I think it might stop all 4 indicators working.

A_morti wrote: Mon Dec 29, 2025 8:55 pm Actually, your multimeter readings might be important. It sounds like you can get power from the battery through the relay (it wouldn't pulse without load) to the switch to each indicator, but it can't get back to earth. The earth path is through the dashboard.
Does it have a single indicator lamp? If so, the PO would have had to fit a "diode mod" to make LEDs work, whether he remembers doing it or not. This frequently involves scotchlock connectors. Ideally you'd undo that to eliminate it from enquiries.
Also if it has a single dashboard bulb and that has failed, I think it might stop all 4 indicators working.

Ah, now I think we might be getting somewhere... The dash only has a single indicator lamp (i.e. serves both sides). When I flick the indicator switch to the LH side the dash light stays off. When I flick it to the RH side the dash light illuminates, but the indicators don't flash. There is what looks to be a loopback plug with a resistor or diode in circuit in the wiring cluster behind the dash, but I recall removing it and it made no difference. It looks kinda 'factory' so I left it alone.

I have tried replacing the relay with a known good one, and it made no difference. It's only a two-pin relay and from memory both pins register 12V when activated, but don't take that as gospel; I may be mis-remembering.