G5 flasher and other electrical components

My indicators are no longer flashing, I have ordered a new flasher but when looking at wiring there appear to be two flashers? one below tank and one behind right hand panel. Are they both flashers? Wiring diagram shows 2 but not sure how accurate that is. Is it possible to test if faulty?

Also I am getting to know bike and trying to find out what other electrical components are, have looked in manuals and online a bit but is there an simple guide somewhere?

I must try to meet up with local branch and point to bits I am curious about!!

the indicator relay is behind the side panel, the so called ‘flashing light relay’ below the tank is in fact the headlight relay.take the relay to your local bike or car shop tomorrow and ask for the same again, keep the ordered one for spare, they dont last forever so a spare one is good for checking with the next time the fitted relay stops working.the easist way to check a electrical problem is replacement with a same part in known working order.

northwest2014-07-08 23:54:19

Contact me via PM I have a coloured wiring diagram that may help you, pdf copy via email is free, A3 laminated copy for the workshop £5.00 + £5.00 p&p.
Please do not post any personal details here as it is in the public domain, use the PM system to contact me.

Best wishes Chris

Thanks Chris very helpful
your inbox is full, will try again later
I have downloaded a 1978 G5 wiring diagram from “thisoldtractor” but it doesn’t seem to be entirely accurate for my model


Is the headlight relay a round one like the flasher relay? I’ve looked at parts catalogue online and it shows “1 intermittence coil” and “1 intermittence” dont know what the difference is but they both have same brackets?


No, the headlight relay if you have the original is an oblong transparent plastic shape below tank. My old T3 flasher relay under side panel was round like the original but I just bought a modern cheap square one, does the same job, don’t know if you can get the original round Guzzi one any more…

Original headlamp relay is second one down ELG12735 Relayitalianmotor2014-07-09 10:43:05

I could be wrong buy I think the only round guzzi original relays are for indicators, my 850T3 headlight relay is square (ish) with 4 pins,any old type car spares shop should have these h/light relays, just take the old one with you, as I said above it is allways handy to have a known working spare unit to swop over if you have any problems.as your bike is 30+ years old the relays could have been replaced many a time, ( like mine have) and the same goes for parts of the wiring loom

northwest2014-07-09 10:35:42

So can I assume both round the round relays are for indicators? Shows 2 on wiring and parts list
I have a squareish one under the tank as well that I assumed is for the headlight
Round ones are easily available, and the rubber bracket, from Gutsibits/Motomecca

I am looking at T3 parts list, should be the same, only one round flasher relay, part number: 17 75 05 20 1 Intermittenza shown. Got a link to a G5 part list?

Edit: yep, seen it now on parts list and manual - it does show two, you’re absolutely right, both numbered 30 ‘intermittenza lampeggiatori’. Who’d have thought? Guess it needs two indicator relays then!italianmotor2014-07-09 11:22:14

Do you know any history about your bike?, both Sussex and Norfolk police forces had Guzzi police bikes back in the late 1970’s, some could have been 850T3’s but Sussex did have G5’s, I know that because I got pulled up by one near to Brightons old football ground, he let me off speeding maybe because I was on my T3, if and its a big if, your bike is a ex police one the electrics would had many extras wires relays etc to cope with flashing blue lights radios etc.
northwest2014-07-09 11:24:36

I wondered if one was for the hazards which operate when ignition is off?

So does just one or none of your two indicator relays work?

The second one is supposed to be for when you put your 4 ways on.It is not needed as they work fine with only one.They’re cheap as chips from Halfords etc.BB is right, replacement is the easiest check when they are that cheap.

Not sure if either relay works yet, indicators stopped flashing after I had dismantled dash, which is not going back on. Will swop around later to see what happens.

There are errors in some of the wiring diagrams on the tractor site as to the colours of wires. I now have emptied my inbox, thanks for letting me know it was full.

Regards Chris

My Convert had two round ones too, I assumed one was for the Hazzard lights. I got rid of that when I re did the wiring, I wanted it as simple as possible - less to go wrong.

The G5 has two cylindrical flasher units wired together, the square unit under the tank is the headlamp relay. The hazard lights are fed from fuse 6 in the fuse box via a black and blue wire that is live even when the ignition is off.

I hope this helps

If I remember rightly they're both for hazards and turn indicators, to double the current capacity for hazards mode (else one unit can only do a pair of left or right indicator lamps at a time) they're simply wired in parallel, I've always been amazed that that would work!    Mine is currently using a square Ford unit which has an additional earth wire, but can do indicator and hazard and fast flashing if a bulb is out while indicating. Actually contain electronics.    The old round gizmos are just the old primitive bimetal switches. Not at all sophisticated.
   Ah that may be why, would the indicator switch wiring go through via the dash assembly by any chance? I.e. an electrical break. The dash also has the indicator repeater eejit lights.

New flasher relay arrived, replaced the one under side panel, indicators flashing now, although speed a bit erratic mostly too fast, is that just a poor relay? (Will try a cheap car unit to test some time)