Horn Main Beam Stoplight

[galaxiid]

My horn doesn't go, neither does the main beam, nor stop lamp. 15 Amp fuse fine and dandy. Checked main bulb, looks OK to me.

 

Is there something simple I am missing here?

 

Oh the tacho still does not run but that is a separate issue and am about to operate on it with a hacksaw.

 

It's an 03 V11 Cafetaria

[Mike Stewart]

Check the light relay, it is one of the mini relays that have always been problematic on these bikes. I looked at the wiring diagram in the owners manual and the horn also is powered up through this relay. Not sure about your tach issue though.

 

Do a search on relays and you should find where to buy one that has a higher amp rating.

 

Mike

[galaxiid]

Check the light relay, it is one of the mini relays that have always been problematic on these bikes. I looked at the wiring diagram in the owners manual and the horn also is powered up through this relay. Not sure about your tach issue though.

 

Do a search on relays and you should find where to buy one that has a higher amp rating.

 

Mike

OK I didn't realise that as well as the fuse the relay controls this as well. Yes relays have caused me the biggest problems with this bike, but the easiest fix also! (Replace them)

Thanks

[mznyc]

Check the light relay, it is one of the mini relays that have always been problematic on these bikes. I looked at the wiring diagram in the owners manual and the horn also is powered up through this relay. Not sure about your tach issue though.

 

Do a search on relays and you should find where to buy one that has a higher amp rating.

 

Mike

OK I didn't realise that as well as the fuse the relay controls this as well. Yes relays have caused me the biggest problems with this bike, but the easiest fix also! (Replace them)

Thanks

Also Kiwi Roy has a write-up of a Relay Base Repair which is also a weak point.Worth checking out.

[Kiwi_Roy]

Yes the headlight, Horn, Tacho, Stop light and charging all rely on the starter relay and the headlight relay to work.

I have a theory that the relays hardly ever fail, it's bad relay base contacts that cause you to think they have. Some of mine were quite loose from much relay shuffling.

Here's my write up on checking (and greasing) the contacts. Just pull one terminal at a time so you don't get them mixed.

Relay Base Repair.pdf

 

I had some spare time to burn so I figured out if I put an LED on each of the 87 contacts it would prove out the relay coil, the contacts and the relay base in one fell swoop. It saves the relay shuffle and looks quite sexy.

Relay Base LEDs.pdf

 

Heres a simplified diagram showing how the starter and headlight relay are essential for Tacho and Charging

Guzzi Wiring - Simple.pdf

 

Oh, by the way the starter relay has to be a 5 pin, a 4 pin won't work in that position. The normally closed 87A contact in the starter relay powers up the headlight relay. Don't buy 4 pin relays, 5 pins work in all spots.

 

Enjoy

[Mike Stewart]

Very Nice Kiwi Roy,

 

May I add one more thought to you, I have been taught to drag test all terminals in question. Meaning, taking a male terminal (in this case the same width and thickness of one of the relay terminals) and testing each female terminal in the relay base. This way, there is no need to remove each terminal, just the one/s that are loose fitting. I guess you could make a test terminal from an old relay by soldering on an inch or two of solid wire. Checking the fuse terminals with the drag test is also reccomended. I have seen techicians go nuts tracing wiring problems on automobiles!

 

Mike

[Kiwi_Roy]

Checking the fuse terminals with the drag test is also reccomended. I have seen techicians go nuts tracing wiring problems on automobiles!

 

Mike

A good tip there, actually the relay base contacts are the same as a standard spade connector (2 sizes) so you could use the male half.

 

I tried to unbolt the fuse block on my bike the two screws were super tight. Finally in frustration I grabbed the block and wrenched on it, much to my surprise it popped right out, that's the way it's supposed to be removed, it plugs into a couple of rubber grommets.

[galaxiid]

Thanks for all the informative wisdom. Stupid me. Yes relays are the cause of all grief. I am interrogating and threatening a bosch relay for reasons why it refuses to relate in a harmonious fashion with such an exquisite motorcycle.

 

I will check the links posted by Kiw Roy. Otherwise will post a pic of the relay diavels as a challenging puzzle for people to name the various parts in order to enlighten me further.

 

Thanks again.

Chris

[galaxiid]

Having had some time to go over all the Kiwi Roy downloads, they are most useful and are a big revelation.

 

A good thing to know is just use 5 blade relays. That saves fussing over what to put in as a replacement and what to carry as a spare.

 

Here is my understanding so far expressed in a pictorial:

 

Fill in the gaps (plus other functions) if you wish

 

relay # 1 Starter (only relay that requires 5 blade)

 

relay # 2 Main headlight, also interrupts function of stoplight, tachometer, horn.

 

relay # 3 Sidestand

 

relay # 4 ECU

 

relay # 5 Injection